Communication network system, interference device, management device, vehicle, program, and communication method

Abstract

A communication network system (100) comprises: a plurality of communication devices; a management device (50) that transmits a start signal to the plurality of communication devices; and an interference device (10) that transmits an interference signal which interferes with detection of the start signal by the plurality of communication devices. The plurality of communication devices use a first communication method, in which the communication devices transmit data in prescribed order after detecting the start signal, to communicate with each other. The interference device (10) transmits the interference signal in accordance with a communication error state in the communication network system (100). When a state in which the start signal is not detected continues for a prescribed period of time, the plurality of communication devices switch the communication method to a second communication method, in which, regardless of the prescribed order of the communication devices, a communication device transmits data when the other communication devices are not transmitting data.

Description

Communication network system, jamming device, management device, vehicle, program, and communication method

[0001] The present disclosure relates to a communication network system, a jamming device, a management device, a vehicle, a program, and a communication method.

[0002] Patent Document 1 discloses a communication network system. The communication network system includes a plurality of communication devices. One of the plurality of communication devices includes a management device. The management device transmits a start signal. After the start signal is transmitted, the plurality of communication devices transmit data in a predetermined order for each communication device.

[0003] Japanese Patent Application Laid-Open No. 2023-23504

[0004] As described above, the communication network system prevents collisions of data transmitted by multiple communication devices by specifying the order in which each communication device transmits data. In such a communication network system, if external noise occurs periodically, there is a possibility that communication errors will occur frequently, such as a specific communication device being unable to transmit data.

[0005] In a first aspect of the present disclosure, a communication network system includes a plurality of communication devices, a management device configured to transmit a start signal to the plurality of communication devices, and a jamming device configured to transmit a jamming signal that jams the plurality of communication devices from detecting the start signal. In the communication network system, the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. In the communication network system, the jamming device is configured to transmit the jamming signal in response to a communication error situation in the communication network system. In the communication network system, when a state in which the start signal is not detected continues for a predetermined time, the plurality of communication devices are configured to switch their communication method to a second communication method in which the communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order.

[0006] In a second aspect of the present disclosure, a jamming device is applied to a communication network system. The communication network system includes a plurality of communication devices and a management device that transmits a start signal to the communication devices. The plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. The plurality of communication devices are configured to switch their communication method to a second communication method in which the communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order, if a state in which the start signal is not detected continues for a predetermined time. The jamming device is configured to transmit a jamming signal that jams the plurality of communication devices from detecting the start signal, depending on a communication error situation in the communication network system.

[0007] In a third aspect of the present disclosure, a communication network system includes a plurality of communication devices and a management device configured to transmit a start signal to the plurality of communication devices. In the communication network system, the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. In the communication network system, the management device is configured to stop transmitting the start signal depending on a communication error situation in the communication network system. In the communication network system, when a state in which the start signal is not detected continues for a predetermined time, the plurality of communication devices are configured to switch the communication method to a second communication method in which the communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order.

[0008] In a fourth aspect of the present disclosure, a management device transmits a start signal in a communication network system including a plurality of communication devices. The plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. Meanwhile, the plurality of communication devices are configured to switch communication methods to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order, if a state in which the start signal is not detected continues for a predetermined time. The management device is configured to stop transmitting the start signal depending on the status of a communication error in the communication network system.

[0009] In a fifth aspect of the present disclosure, a communication network system provided in a vehicle includes a plurality of communication devices, a management device configured to transmit a start signal to the plurality of communication devices, and a jamming device configured to transmit a jamming signal that jams the plurality of communication devices from detecting the start signal. In the vehicle equipped with the communication network system, the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. In the vehicle equipped with the communication network system, the jamming device is configured to transmit the jamming signal in response to a communication error situation in the communication network system. In the vehicle equipped with the communication network system, when a state in which the start signal is not detected continues for a predetermined time, the plurality of communication devices are configured to switch their communication method to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order.

[0010] In a sixth aspect of the present disclosure, a vehicle equipped with a communication network system includes a plurality of communication devices and a management device configured to transmit a start signal to the plurality of communication devices. In the vehicle equipped with the communication network system, the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. In the vehicle equipped with the communication network system, the management device is configured to stop transmitting the start signal depending on the status of a communication error in the communication network system. In the vehicle equipped with the communication network system, when a state in which the start signal is not detected continues for a predetermined time, the plurality of communication devices are configured to switch the communication method to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order.

[0011] In a seventh aspect of the present disclosure, a program is executed by a jamming device in a communication network system. The communication network system includes a plurality of communication devices and a management device configured to transmit a start signal. The plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. The plurality of communication devices are configured to switch the communication method to a second communication method in which the communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order, if a state in which the start signal is not detected continues for a predetermined time. The program causes the jamming device to transmit a jamming signal that jams the plurality of communication devices from detecting the start signal, based on a communication error status in the communication network system.

[0012] In an eighth aspect of the present disclosure, a program is executed by a management device configured to transmit a start signal in a communication network system including a plurality of communication devices. The plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. The plurality of communication devices are configured to switch the communication method to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order, if a state in which the start signal is not detected continues for a predetermined time. The program causes the management device to stop transmitting the start signal based on the status of a communication error in the communication network system.

[0013] In a ninth aspect of the present disclosure, a communication method is a communication method in a communication network system. The communication method includes a step in which a management device transmits a start signal. The communication method includes a step in which a plurality of communication devices communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. The communication method includes a step in which a jamming device transmits a jamming signal based on a communication error situation in the communication network system. The communication method includes a step in which, when a state in which the plurality of communication devices do not detect the start signal continues for a predetermined time, the communication device switches the communication method to a second communication method in which the communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order.

[0014] In a tenth aspect of the present disclosure, a communication method is a communication method in a communication network system. The communication method includes a step in which a management device transmits a start signal. The communication method includes a step in which a plurality of communication devices communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal. The communication method includes a step in which the management device stops transmitting the start signal based on a communication error status in the communication network system. The communication method includes a step in which, when a state in which the plurality of communication devices do not detect the start signal continues for a predetermined time, the communication device switches the communication method to a second communication method in which the communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order.

[0015] Each of the above aspects can suppress communication errors occurring in a specific communication device among a plurality of communication devices.

[0016] FIG. 1 is a schematic diagram showing the configuration of a communication network system of an embodiment. FIG. 2 is a schematic diagram showing an example of a mode in which multiple communication devices in the communication network system of FIG. 1 transmit data using a first communication method. FIG. 3 is a sequence diagram showing a mode of communication using the first communication method performed by a management device, a first communication device, and a second communication device in the communication network system of FIG. 1. FIG. 4 is a flowchart showing the flow of processing related to data transmission using the first communication method performed by a communication device in the communication network system of FIG. 1. FIG. 5 is a schematic diagram showing an example of a mode in which multiple communication devices in the communication network system of FIG. 1 transmit data using a second communication method. FIG. 6 is a sequence diagram showing a mode of communication using the second communication method performed by a management device, a first communication device, and a second communication device in the communication network system of FIG. 1. FIG. 7 is a flowchart showing the flow of processing related to data transmission using the second communication method performed by a communication device in the communication network system of FIG. 1. FIG. 8 is a sequence diagram showing an example of a communication mode when a management device, a first communication device, and a second communication device in the communication network system of FIG. 1 switch the communication method to the second communication method. FIG. 9 is a table showing the status of communication errors in the communication network system, acquired by the first communication device in the communication network system of FIG. 1. FIG. 10 is a flowchart showing the flow of processing related to transmission of a jamming signal executed by the first communication device in the communication network system of FIG. 1. FIG. 11 is a flowchart showing the flow of processing related to switching to the second communication method executed by the communication device in the communication network system of FIG. 1. FIG. 12 is a flowchart showing the flow of processing related to resumption of transmission of a start signal executed by the management device in the communication network system of FIG. 1. FIG. 13 is a sequence diagram showing an example of a communication mode when a management device, a first communication device, and a second communication device in the communication network system of a first modified example switch the communication method to the second communication method. FIG. 14 is a flowchart showing the flow of processing related to transmission of a jamming request signal executed by the second communication device in the communication network system of the first modified example.15 is a sequence diagram showing an example of a communication mode when a management device, a first communication device, and a second communication device in a communication network system of a second modified example switch the communication method to the second communication method. FIG. 16 is a flowchart showing a processing flow related to transmission of a jamming request signal executed by the second communication device in the communication network system of the second modified example. FIG. 17 is a flowchart showing a processing flow related to transmission of a jamming signal executed by the first communication device in the communication network system of the second modified example. FIG. 18 is a sequence diagram showing an example of a communication mode when a management device, a first communication device, and a second communication device in a communication network system of a third modified example switch the communication method to the second communication method. FIG. 19 is a flowchart showing a processing flow related to stopping transmission of a start signal executed by the management device in the communication network system of the third modified example. FIG. 20 is a sequence diagram showing an example of a communication mode when a management device, a first communication device, and a second communication device in a communication network system of a fourth modified example switch the communication method to the second communication method. Fig. 21 is a flowchart showing the flow of processing related to transmission of a stop request signal executed by a first communication device in a communication network system of a fourth modified example. Fig. 22 is a sequence diagram showing an example of communication mode when a management device, a first communication device, and a second communication device in a communication network system of a fifth modified example switch the communication method to a second communication method. Fig. 23 is a flowchart showing the flow of processing related to transmission of a stop request signal executed by a first communication device in a communication network system of a fifth modified example. Fig. 24 is a flowchart showing the flow of processing related to stopping transmission of a start signal executed by a management device in a communication network system of a fifth modified example.

[0017] An embodiment of a communication network system will be described below with reference to Figures 1 to 12. <Configuration of communication network system 100> As shown in Figure 1, the communication network system 100 includes a plurality of communication devices. The plurality of communication devices are connected to each other via a communication bus 30 so as to be able to communicate with each other.

[0018] The communication network system 100 is applied to a vehicle 101. The plurality of communication devices constituting the communication network system 100 are electronic control units (ECUs) in the vehicle 101. The plurality of communication devices communicate with each other via a communication bus 30 to realize specific functions in the vehicle 101.

[0019] One of the multiple communication devices that make up the communication network system 100 is a management device 50. As shown in Fig. 1, the management device 50 includes a processing device 51 and a storage device 52. Programs are stored in the storage device 52. The processing device 51 executes the programs stored in the storage device 52 to perform various processes. The processing device 51, i.e., the processing circuit, includes a processor.

[0020] One of the multiple communication devices that make up the communication network system 100 is a first communication device 10. As shown in Fig. 1, the first communication device 10 includes a processing device 11 and a storage device 12. Programs are stored in the storage device 12. The programs stored in the storage device 12 include programs that control the communication methods of the multiple communication devices in the communication network system 100. The processing device 11 executes the programs stored in the storage device 12 to perform various processes. The processing device 11, i.e., the processing circuit, includes a processor.

[0021] One of the multiple communication devices constituting the communication network system 100 is a second communication device 20. As shown in Fig. 1, the second communication device 20 includes a processing device 21 and a storage device 22. Programs are stored in the storage device 22. The processing device 21 executes the programs stored in the storage device 22 to perform various processes. The processing device 21, i.e., the processing circuit, includes a processor.

[0022] The processing unit (processing circuit) may include one or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that perform at least some of the processes. Alternatively, the processing unit (processing circuit) may include a combination of one or more processors and one or more dedicated hardware circuits. The storage device may include RAM, ROM, etc. The storage device, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0023] Each communication device transmits data through the communication bus 30 to realize a specific function. Hereinafter, data transmitted by the first communication device 10 will be referred to as first data 41. Data transmitted by the second communication device 20 will be referred to as second data 42. Data transmitted by the management device 50 will be referred to as third data 43. Each communication device uses the first communication method as the communication method for communicating data with each other.

[0024] Each communication device does not transmit data when the function it realizes is not necessary for controlling the vehicle 101. In other words, the first data 41 to the third data 43 are not transmitted at times when they are not necessary for controlling the vehicle 101.

[0025] The management device 50 transmits a start signal 40 in addition to the third data 43. The start signal 40 will be described later. The first communication device 10 transmits a jamming signal in addition to the first data 41. The jamming signal will also be described later.

[0026] In this embodiment, the communication network system 100 includes three communication devices and one communication bus. The number of communication devices included in the communication network system 100 is not limited to this embodiment. Furthermore, the manner in which the communication devices are connected, i.e., the topology of the communication network system 100, is also not limited to this embodiment.

[0027] <Overview of First Communication Method> Fig. 2 shows an example of how data is transmitted to the communication bus 30 in the first communication method. The rectangles in Fig. 2 represent data transmitted by each communication device. The area of ​​each rectangle in Fig. 2 is represented as being larger in proportion to the data capacity. Therefore, in Fig. 2, the second data 42 has the largest capacity. Each communication device does not transmit the same amount of data every time. Therefore, although the second data 42 has the largest capacity in Fig. 2, this does not necessarily mean that the second data 42 has the largest capacity in other situations.

[0028] In Fig. 2, data is transmitted in order from left to right. As shown in Fig. 2, in the first communication method, a start signal 40 is first transmitted. The management device 50 periodically transmits the start signal 40. The start signal 40 is a signal that notifies each communication device connected to the communication bus 30 that data communication using the first communication method has started.

[0029] Each communication device that has detected the start signal 40 transmits data that needs to be transmitted using the first communication method. In the first communication method, the order in which each communication device transmits data after the start signal 40 is transmitted is determined in advance. The order may be determined when the communication network system 100 is constructed. The order may also be determined by the management device 50. When the management device 50 determines the order, for example, the management device 50 transmits the start signal 40 or another signal containing information indicating the order. This allows each communication device to know the order in which to transmit data.

[0030] In the example shown in Fig. 2, in the communication network system 100, after a start signal 40 is transmitted, the first communication device 10 transmits first data 41. In the example shown in Fig. 2, in the communication network system 100, after the first data 41 is transmitted, the second communication device 20 transmits second data 42. In the example shown in Fig. 2, in the communication network system 100, after the second data 42 is transmitted, the management device 50 transmits third data 43. The order in which communication devices transmit data in the first communication method is not limited to the example described in this embodiment.

[0031] In this way, each communication device transmits data in turn after the start signal 40 is transmitted. In order to transmit data in turn after the start signal 40 is transmitted, each communication device grasps which communication device's turn it is to transmit data.

[0032] In the example shown in FIG. 2 , immediately after the start signal 40 is transmitted, each communication device recognizes that it is now the first communication device 10's turn to transmit the first data 41. In the example shown in FIG. 2 , after the first data 41 is transmitted, each communication device recognizes that it is now the second communication device 20's turn to transmit the second data 42. As described above, the first data 41 to the third data 43 are not transmitted at times that are not necessary for the control of the vehicle 101. That is, depending on the functions executed in the vehicle 101 and the content of the information to be communicated, the first communication device 10 may not transmit the first data 41. In this case, when a certain period of time has passed without the first data 41 being transmitted after it is the first communication device 10's turn to transmit the first data 41, each communication device determines that the first communication device 10 will not transmit data. Then, because the certain period of time has passed without the first data 41 being transmitted, each communication device recognizes that it is now the second communication device 20's turn to transmit the second data 42.

[0033] 2 , after the second data 42 is transmitted, each communication device recognizes that it is now the management device 50's turn to transmit the third data 43. If the second communication device 20 does not transmit the second data 42, each communication device determines that the second communication device 20 will not transmit data when a certain period of time has passed without the second data 42 being transmitted after it is the second communication device 20's turn to transmit the second data 42. Then, because the certain period of time has passed without the second data 42 being transmitted, each communication device recognizes that it is now the management device 50's turn to transmit the third data 43.

[0034] 3 shows communication in the first communication method between the first communication device 10, the second communication device 20, and the management device 50. As shown in FIG. 3, in the first communication method, the management device 50 first transmits a start signal 40 to the first communication device 10 and the second communication device 20.

[0035] Next, the first communication device 10 transmits the first data 41 to the management device 50 and the second communication device 20. At this time, the first communication device 10 transmits the first data 41 after determining that it is now its turn to transmit data. Depending on the function being executed in the vehicle 101 and the content of the information being communicated, the first communication device 10 may not transmit the first data 41.

[0036] Next, the second communication device 20 transmits the second data 42 to the management device 50 and the first communication device 10. At this time, the second communication device 20 transmits the second data 42 after determining that it is now its turn to transmit data. As with the first communication device 10, the second communication device 20 may not transmit the second data 42 depending on the function being executed in the vehicle 101 and the content of the information being communicated.

[0037] Next, the management device 50 transmits the third data 43 to the first communication device 10 and the second communication device 20. At this time, the management device 50 transmits the third data 43 after determining that it is now its turn to transmit data. As with the first communication device 10, the management device 50 may not transmit the third data 43 depending on the function being executed in the vehicle 101 and the content of the information being communicated.

[0038] <Processing Executed by Processing Device of Each Communication Device in First Communication Method> Fig. 4 shows a series of processing executed by each communication device in the communication network system 100 in the first communication method. The first communication device 10, the second communication device 20, and the management device 50 execute the processing shown in Fig. 4 after determining that it is now their turn to transmit data.

[0039] This series of processes is executed by the processing devices of the communication devices in the communication network system 100. That is, this series of processes is executed by the processing device 11 of the first communication device 10, the processing device 21 of the second communication device 20, and the processing device 51 of the management device 50.

[0040] First, the flow of the processing performed by the processing device 11 of the first communication device 10 as shown in Fig. 4 will be described. As shown in Fig. 4, when this processing starts, the processing device 11 determines in step S11 whether or not there is data to be transmitted by the processing device 11. In other words, the processing device 11 determines whether or not the first communication device 10 needs to transmit the first data 41.

[0041] In the process of step S11, if the processing device 11 determines that there is no data to transmit (step S11: NO), the processing device 11 ends this series of processes. In other words, if the processing device 11 determines that there is no need to transmit the first data 41, the processing device 11 ends this series of processes.

[0042] On the other hand, in the process of step S11, if the processing device 11 determines that it has data to transmit (step S11: YES), it proceeds to the process of step S12. That is, if the processing device 11 determines that it is necessary to transmit the first data 41, it proceeds to the process of step S12. In the process of step S12, the processing device 11 transmits the first data 41. After transmitting the first data 41, the processing device 11 ends this series of processes.

[0043] The processing device 21 of the second communication device 20 executes the same processing as the processing device 11 of the first communication device 10. As shown in Fig. 4, when this series of processing starts, in the processing of step S11, the processing device 21 determines whether or not there is data to be transmitted by itself. In other words, the processing device 21 determines whether or not the second communication device 20 needs to transmit the second data 42.

[0044] In the process of step S11, if the processing device 21 determines that there is no data to transmit (step S21: NO), the processing device 21 ends this series of processes. In other words, if the processing device 21 determines that there is no need to transmit the second data 42, the processing device 21 ends this series of processes.

[0045] On the other hand, in the process of step S11, if the processing device 21 determines that it has data to transmit (step S11: YES), it proceeds to the process of step S12. That is, if the processing device 21 determines that it is necessary to transmit the second data 42, it proceeds to the process of step S12. In the process of step S12, the processing device 21 transmits the second data 42. After transmitting the second data 42, the processing device 21 ends this series of processes.

[0046] The processing device 51 of the management device 50 executes the same processing as the processing device 11 of the first communication device 10. As shown in Fig. 4, when this series of processing starts, in the processing of step S11, the processing device 51 determines whether or not there is data to be transmitted by itself. In other words, the processing device 51 determines whether or not the management device 50 needs to transmit the third data 43.

[0047] In the process of step S11, if the processing device 51 determines that there is no data to transmit (step S11: NO), the processing device 51 ends this series of processes. In other words, if the processing device 51 determines that there is no need to transmit the third data 43, the processing device 51 ends this series of processes.

[0048] On the other hand, in the process of step S11, if the processing device 51 determines that it has data to transmit (step S11: YES), it proceeds to the process of step S12. That is, if the processing device 51 determines that it is necessary to transmit the third data 43, it proceeds to the process of step S12. In the process of step S12, the processing device 51 transmits the third data 43. After transmitting the third data 43, the processing device 51 ends this series of processes.

[0049] <Overview of the Second Communication Method> As described above, in the communication network system 100, the communication devices communicate with each other by transmitting data using the first communication method. In the first communication method, the order in which the communication devices transmit data is predetermined. After the management device 50 transmits the start signal 40, the communication devices transmit data in a predetermined order.

[0050] In the first communication method, the timing at which each communication device transmits data may become somewhat periodic due to the periodic transmission of the start signal 40 and the fixed order in which each communication device transmits data. Therefore, in the first communication method, if external noise occurs periodically, the timing at which a specific communication device among the multiple communication devices transmits data may coincide with the timing at which the noise occurs. In this case, as long as the timing at which the specific communication device transmits data coincides with the timing at which the noise occurs, a communication error occurs in which the specific communication device is unable to transmit data.

[0051] In addition to the above-mentioned cases, in the first communication method, for example, noise may occur, which may cause at least one communication device to be unable to receive a message properly. Furthermore, in the first communication method, for example, noise may occur, which may limit the time available for data transmission, which may cause at least one communication device to be unable to transmit data sufficiently. Thus, in the first communication method, various types of communication errors may occur due to noise.

[0052] In the communication network system 100, when a communication error due to such noise occurs, the multiple communication devices switch the communication method from the first communication method to the second communication method. FIG. 5 shows an example of how data is transmitted to the communication bus 30 in the second communication method. Similar to FIG. 2, the rectangles in FIG. 5 represent data transmitted by each communication device. Similar to FIG. 2, the rectangles in FIG. 5 are represented with larger areas in proportion to the data volume. Therefore, in FIG. 5, the second data 42 has the largest volume. Each communication device does not transmit the same volume of data every time. Therefore, although the second data 42 has the largest volume in FIG. 5, this does not necessarily mean that the second data 42 has the largest volume in other situations.

[0053] In Fig. 5, data is transmitted in order from left to right, as in Fig. 2. In the example shown in Fig. 5, first, the second communication device 20 transmits second data 42. Next, the management device 50 transmits third data 43. Next, the first communication device 10 transmits first data 41.

[0054] 5 , unlike the first communication method, the second communication method does not transmit a start signal 40. In the second communication method, each communication device transmits data at any timing without waiting for the management device 50 to transmit the start signal 40.

[0055] In the example of the mode shown in Fig. 2, data is transmitted in the order of first data 41, second data 42, and third data 43. On the other hand, in the example of the mode shown in Fig. 5, data is transmitted in the order of second data 42, third data 43, and first data 41. As described above, in the second communication method, each communication device transmits data at any timing. That is, unlike the first communication method, in the second communication method, the order in which data is transmitted is not fixed. Therefore, the order in which multiple communication devices transmit data in the second communication method is not limited to the order shown in Fig. 5.

[0056] In the second communication method, the order in which each communication device transmits data is not fixed, so there is a possibility that multiple communication devices may transmit data at the same time. In this case, the data will collide with each other, and the multiple communication devices will not be able to transmit data to other communication devices. Therefore, in the second communication method, each communication device transmits data only after confirming that other communication devices are not transmitting data.

[0057] Even if multiple communication devices confirm that other communication devices are not transmitting data, if multiple communication devices start transmitting data at the same time, the data will collide. In this case, the multiple communication devices detect that the data has collided. After waiting a certain period of time, each communication device retransmits the data that it was unable to transmit after confirming that other communication devices are not transmitting data. By repeating this retransmission process, each communication device is finally able to transmit its data.

[0058] In this way, in the second communication method, each communication device in the communication network system 100 transmits data when no other communication device is transmitting data, regardless of the predetermined order.

[0059] 6 shows communication between the first communication device 10, the second communication device 20, and the management device 50 in the second communication method. As described above, in the second communication method, the order in which each communication device transmits data is not fixed. Fig. 6 shows communication when each communication device transmits data in the order shown in Fig. 5.

[0060] 6, first, the second communication device 20 transmits the second data 42 to the first communication device 10 and the management device 50. At this time, the second communication device 20 transmits the second data 42 after confirming that the management device 50 and the first communication device 10 are not transmitting data.

[0061] 6 , next, the management device 50 transmits the third data 43 to the first communication device 10 and the second communication device 20. At this time, the management device 50 transmits the third data 43 after confirming that the first communication device 10 and the second communication device 20 are not transmitting data.

[0062] 6 , the first communication device 10 then transmits the first data 41 to the second communication device 20 and the management device 50. At this time, the first communication device 10 transmits the first data 41 after confirming that the management device 50 and the second communication device 20 are not transmitting data.

[0063] <Processing Executed by Processing Device of Each Communication Device in the Second Communication Method> Fig. 7 shows a series of processing executed when each communication device in the communication network system 100 transmits data in the second communication method. That is, the first communication device 10, the second communication device 20, and the management device 50 execute the processing shown in Fig. 7 when transmitting data.

[0064] This series of processes is executed by the processing devices of the communication devices in the communication network system 100. That is, this series of processes is executed by the processing device 11 of the first communication device 10, the processing device 21 of the second communication device 20, and the processing device 51 of the management device 50.

[0065] First, a flow of the processing performed by the processing device 11 of the first communication device 10 when the processing device 11 executes the series of processes shown in Fig. 7 will be described. As shown in Fig. 7, when this series of processes starts, in step S21, the processing device 11 determines whether or not there is a communication device transmitting data in the communication network system 100. At this time, if the first communication device 10 is receiving the third data 43 transmitted by the management device 50 or the second data 42 transmitted by the second communication device 20, the processing device 11 determines that there is a communication device transmitting data.

[0066] In the process of step S21, if the processing device 11 determines that there is a communication device transmitting data (step S21: YES), the processing device 11 repeats the process of step S21. On the other hand, in the process of step S21, if the processing device 11 determines that there is no communication device transmitting data (step S21: NO), the processing device 11 proceeds to the process of step S22. In the process of step S22, the processing device 11 transmits data. The data transmitted by the first communication device 10 is first data 41. Therefore, the processing device 11 transmits the first data 41 in the process of step S22.

[0067] In the next step S23, the processing device 11 determines whether the transmitted data has collided with other data. When a communication device in the communication network system 100 detects a data collision, the communication device that detected the collision transmits a jam signal. The jam signal is a signal that notifies that a data collision has occurred. The processing device 11 determines whether the transmitted data has collided with other data based on whether the jam signal has been received.

[0068] In the process of step S23, if the processing device 11 determines that the transmitted data has collided with other data (step S23: YES), the processing proceeds to step S24. In the process of step S24, the processing device 11 retransmits the first data 41. If the processing device 11 retransmits the first data 41 immediately after a data collision occurs, there is a possibility that the retransmitted first data 41 will collide again with the data that previously collided. Therefore, the processing device 11 waits a certain time before transmitting the first data 41. Another communication device that transmitted the data that collided with the first data 41 also waits a certain time before retransmitting the data, just like the processing device 11. Therefore, if the waiting time of the processing device 11 and the waiting time of the other communication device differ, the processing device 11 and the other communication device can transmit data without colliding again. After retransmitting the first data 41, the processing device 11 again executes the process of step S23.

[0069] In the process of step S23, if the processor 11 determines that the transmitted data does not collide with other data (step S23: NO), the series of processes shown in FIG. 7 ends.

[0070] The processing device 21 of the second communication device 20 also executes the series of processes shown in Fig. 7 in the same manner as the processing device 11. As shown in Fig. 7, when this series of processes starts, in the process of step S21, the processing device 21 determines whether or not there is a communication device transmitting data in the communication network system 100. At this time, the processing device 21 determines that there is a communication device transmitting data when the second communication device 20 is receiving the third data 43 transmitted by the management device 50 or the first data 41 transmitted by the first communication device 10.

[0071] In the process of step S21, if the processing device 21 determines that there is a communication device transmitting data (step S21: YES), the processing device 21 repeats the process of step S21. On the other hand, in the process of step S21, if the processing device 21 determines that there is no communication device transmitting data (step S21: NO), the processing device 21 proceeds to the process of step S22. In the process of step S22, the processing device 21 transmits the data. The data transmitted by the second communication device 20 is second data 42. Therefore, the processing device 21 transmits the second data 42 in the process of step S22.

[0072] In the next step S23, the processing device 21 determines whether the transmitted data has collided with other data based on whether a jam signal has been received.

[0073] In the process of step S23, if the processing device 21 determines that the transmitted data has collided with other data (step S23: YES), the processing device 21 proceeds to the process of step S24. In the process of step S24, the processing device 21 retransmits the second data 42. At this time, the processing device 21 waits for a certain period of time before transmitting the second data 42. After retransmitting the second data 42, the processing device 21 executes the process of step S23 again.

[0074] In the process of step S23, if the processor 21 determines that the transmitted data does not collide with other data (step S23: NO), the series of processes shown in FIG. 7 ends.

[0075] The processing device 51 of the management device 50 also executes the series of processes shown in Fig. 7 in the same manner as the processing device 11. As shown in Fig. 7, when this series of processes starts, in the process of step S21, the processing device 51 determines whether or not there is a communication device transmitting data in the communication network system 100. At this time, the processing device 51 determines that there is a communication device transmitting data when the management device 50 is receiving the first data 41 transmitted by the first communication device 10 or the second data 42 transmitted by the second communication device 20.

[0076] In the process of step S21, if the processing device 51 determines that there is a communication device transmitting data (step S21: YES), the processing device 51 repeats the process of step S21. On the other hand, in the process of step S21, if the processing device 51 determines that there is no communication device transmitting data (step S21: NO), the processing device 51 proceeds to the process of step S22. In the process of step S22, the processing device 51 transmits data. The data transmitted by the management device 50 is the third data 43. Therefore, the processing device 51 transmits the third data 43 in the process of step S22.

[0077] In the next step S23, the processing device 51 determines whether the transmitted data has collided with other data based on whether a jam signal has been received.

[0078] In the process of step S23, if the processing device 51 determines that the transmitted data has collided with other data (step S23: YES), the processing device 51 proceeds to the process of step S24. In the process of step S24, the processing device 51 retransmits the second data 42. At this time, the processing device 51 waits a certain time before transmitting the third data 43. After retransmitting the third data 43, the processing device 51 executes the process of step S23 again.

[0079] In the process of step S23, if the processor 51 determines that the transmitted data does not collide with other data (step S23: NO), the series of processes shown in FIG. 7 ends.

[0080] <Data Transmission and Reception When Communication Device Switches Communication Method> As described above, the communication network system 100 switches the communication method to the second communication method when communication errors occur frequently for a specific communication device in the first communication method. Fig. 8 shows a specific example of communication between the first communication device 10, the second communication device 20, and the management device 50 when switching the communication method.

[0081] 8 is executed when two conditions are met. The first condition is that the number of communication errors that occur while any communication device in the communication network system 100 transmits data a predetermined number of times is equal to or greater than a predetermined value. The predetermined value will be described later.

[0082] The second condition is that multiple communication devices in the communication network system 100 are capable of switching to the second communication method. A state in which multiple communication devices are capable of switching to the second communication method means a state in which the operation of the vehicle 101 is not hindered even if the multiple communication devices switch their communication method to the second communication method. As described above, in the second communication method, when one communication device is transmitting data, the other communication devices cannot transmit data. In other words, in the second communication method, opportunities for each communication device to transmit data are not guaranteed. Therefore, depending on the situation of the vehicle 101, switching the communication method of the communication devices in the communication network system 100 may result in a specific communication device being unable to transmit data for a long period of time. Depending on the situation of the vehicle 101, the communication network system 100 does not switch the communication method of the multiple communication devices to the second communication method in order to prioritize ensuring opportunities to transmit data.

[0083] When these two conditions are met, the first communication device 10 transmits a jamming signal, as shown in the upper part of Fig. 8. The jamming signal is a signal that interferes with the detection of the start signal 40 by each communication device in the communication network system 100. In this way, in this example, the first communication device 10 serves as a jamming device that transmits a jamming signal depending on the state of a communication error.

[0084] The first communication device 10 transmits a jamming signal at the same timing as the management device 50 transmits the start signal 40. As a result, the first communication device 10, the second communication device 20, and the management device 50 do not sense the start signal 40.

[0085] 8, the first communication device 10, the second communication device 20, and the management device 50 switch to the second communication method when a state in which they do not sense the start signal 40 continues for a predetermined time. In this way, each communication device in the communication network system 100 switches the communication method to the second communication method.

[0086] 8, the first communication device 10, the second communication device 20, and the management device 50 switch to the second communication method and then communicate with each other using the second communication method. That is, the first communication device 10, the second communication device 20, and the management device 50 communicate with each other in the manner illustrated in FIG.

[0087] 8, the management device 50 transmits a start signal 40 if a state in which no data is transmitted continues for a certain period of time after transitioning to the second communication method. The first communication device 10 and the second communication device 20 that receive the start signal 40 transition to the first communication method. The management device 50 that transmitted the start signal 40 also transitions to the first communication method. In this way, each communication device in the communication network system 100 returns its communication method to the first communication method.

[0088] 8, the first communication device 10 transmits a jamming signal in accordance with the communication error status. The first communication device 10 acquires the communication error status in the communication network system 100 in order to transmit a jamming signal as necessary.

[0089] 9 is a table showing the status of communication errors in the communication network system 100, acquired by the first communication device 10. As shown in FIG. 9, the first communication device 10 acquires, as the status of communication errors, information on the number of communication errors that occurred while each communication device transmitted data a predetermined number of times. In other words, the first communication device 10 acquires information on the number of communication errors that occurred for each of the first communication device 10, the second communication device 20, and the management device 50, while each of them transmitted data a predetermined number of times. In FIG. 9, the number of communication errors for each communication device acquired by the first communication device 10 is represented by a symbol such as "A1," "A2," or "A3."

[0090] As shown in Figure 9, a default value is set for each communication device. The default value is a threshold value used by the first communication device 10 to determine whether to switch the communication method from the first communication method to the second communication method based on the number of communication errors in each communication device. The default value may be different for each communication device, or may be the same for some of the communication devices. The first communication device 10 transmits a jamming signal when the number of communication errors in any of the communication devices exceeds the default value. In Figure 9, the default values ​​set for each communication device are represented by symbols such as "B1", "B2", and "B3".

[0091] 10 shows a series of processes executed when the first communication device 10 transmits a jamming signal. The series of processes is executed by the processing device 11 of the first communication device 10 in accordance with a program stored in the storage device 12.

[0092] This series of processes is executed when the first communication device 10 acquires information on the number of communication errors that occurred while transmitting data a predetermined number of times for either the first communication device 10, the second communication device 20, or the management device 50.

[0093] As shown in FIG. 10, when this series of processes is started, in the process of step S101, the processing device 11 determines whether the number of communication errors in the communication device from which information has been obtained is equal to or greater than a predetermined value.

[0094] In the process of step S101, if the processing device 11 determines that the number of communication errors is not equal to or greater than the predetermined value (step S101: NO), the processing device 11 ends this series of processes. In other words, if the processing device 11 determines that the number of communication errors is less than the predetermined value, the processing device 11 ends this series of processes.

[0095] In the process of step S101, if the processing device 11 determines that the number of communication errors is equal to or greater than the predetermined value (step S101: YES), the processing device 11 proceeds to the process of step S102.

[0096] In the processing of step S102, the processing device 11 grasps the status of the vehicle 101. The processing device 11 grasps the status of the vehicle 101 based on data transmitted by at least one communication device in the communication network system 100. For example, when the status of the vehicle 101 is that the vehicle 101 is in autonomous driving, at least one communication device in the communication network system 100 that communicates during autonomous driving to realize the autonomous driving function transmits data indicating that the vehicle 101 is in autonomous driving.

[0097] In the next step S103, the processing device 11 determines whether or not the plurality of communication devices in the communication network system 100 can switch to the second communication method. In the step S103, the processing device 11 determines whether or not the plurality of communication devices can switch to the second communication method based on the status of the vehicle 101 grasped in the step S102.

[0098] The processing device 11 determines that the plurality of communication devices cannot switch to the second communication method when the vehicle 101 is in a state where securing data transmission opportunities needs to be prioritized. For example, the processing device 11 determines that the plurality of communication devices cannot switch to the second communication method when the vehicle 101 is in autonomous driving. Furthermore, for example, the processing device 11 determines that the plurality of communication devices cannot switch to the second communication method when the vehicle 101 is undergoing a fault diagnosis.

[0099] In the process of step S103, if the processing device 11 determines that the plurality of communication devices cannot switch to the second communication method (step S103: NO), the processing device 11 ends this series of processes.

[0100] In the process of step S103, if the processing device 11 determines that the plurality of communication devices can switch to the second communication method (step S103: YES), the processing device 11 proceeds to the process of step S104. In the process of step S104, the processing device 11 transmits a jamming signal. This process corresponds to the process executed by the first communication device 10 in the upper part of Fig. 8. In this way, the processing device 11 transmits a jamming signal based on the acquired communication error status and the grasped status of the vehicle 101.

[0101] The processing device 11 that transmitted the jamming signal ends this series of processes. <Processing for Communication Device to Switch Communication Method to Second Communication Method> Fig. 11 shows a series of flows when each communication device in the communication network system 100 switches the communication method from the first communication method to the second communication method. This series of processes is executed by the processing device 11 of the first communication device 10, the processing device 21 of the second communication device 20, and the processing device 51 of the management device 50. This process corresponds to the process executed by the first communication device 10, the second communication device 20, and the management device 50 shown in the middle part of Fig. 8.

[0102] First, a flow of the processing performed by the processing device 11 of the first communication device 10 as shown in Fig. 11 will be described. The processing device 11 performs the processing shown in Fig. 11 when it does not sense the start signal 40 for a predetermined time.

[0103] 11 , when this series of processes starts, in the process of step S31, the processing device 11 transitions to the second communication method. At this time, the processing device 11 switches the flag that determines the communication method in the first communication device 10 from the flag for the first communication method to the flag for the second communication method. As a result, the communication method in the first communication device 10 transitions from the first communication method to the second communication method. In this way, the first communication device 10 switches the communication method from the first communication method to the second communication method.

[0104] In the process of step S32, the processing device 11 determines whether or not there is data to transmit. The processing device 11 determines whether or not there is data to transmit based on whether or not the first communication device 10 needs to transmit the first data 41.

[0105] In the process of step S32, if the processing device 11 determines that there is no data to transmit (step S32: NO), the processing device 11 ends this series of processes. In the process of step S32, if the processing device 11 determines that there is data to transmit (step S32: YES), the processing device 11 proceeds to the process of step S33. In the process of step S33, the processing device 11 executes the offset time setting process.

[0106] The offset time setting process is a process for setting an offset time. The offset time is the time from when a communication device switches to the second communication method to when it starts transmitting data when there is data to transmit immediately after switching the communication method to the second communication method. In the second communication method, the order in which each communication device transmits data is not set. Each communication device sets an offset time from when it switches to the second communication method to when it starts transmitting data, thereby preventing data collisions from occurring immediately after each communication device switches to the second communication method.

[0107] For example, the processing device 11 sets a shorter offset time as the volume of the first data 41 to be transmitted increases, thereby enabling the processing device 11 to preferentially transmit the first data 41 having a larger volume in the second communication method.

[0108] When setting the offset time, the processing device 11 sets a shorter offset time, for example, the higher the priority of the first communication device 10. In this case, a priority is determined in advance for each communication device in the communication network system 100. By setting a shorter offset time the higher the priority, the processing device 11 can prioritize data transmission for communication devices with higher priorities in the communication network system 100.

[0109] In the process of step S34, the processing device 11 transmits the data taking the offset time into consideration. The processing device 11 starts transmitting the first data 41 after the offset time set in the process of step S33 has elapsed.

[0110] The processing device 11 that transmitted the first data 41 ends this series of processes. The processing device 21 of the second communication device 20 also executes the series of processes shown in Fig. 11 in the same manner as the processing device 11. The processing device 21 executes the series of processes shown in Fig. 11 when it does not sense the start signal 40 for a predetermined time.

[0111] 11 , when this series of processes starts, in the process of step S31, the processing device 21 transitions to the second communication method. At this time, the processing device 21 switches the flag that determines the communication method of the second communication device 20 from the flag for the first communication method to the flag for the second communication method. As a result, the communication method of the second communication device 20 transitions from the first communication method to the second communication method. In this way, the second communication device 20 switches the communication method from the first communication method to the second communication method.

[0112] In the next step S32, the processing device 21 determines whether there is data to transmit. The processing device 21 determines whether there is data to transmit based on whether the second communication device 20 needs to transmit the second data 42.

[0113] In the process of step S32, if the processing device 21 determines that there is no data to transmit (step S32: NO), the processing device 21 ends this series of processes. In the process of step S32, if the processing device 21 determines that there is data to transmit (step S32: YES), the processing device 21 proceeds to the process of step S33. In the process of step S33, the processing device 21 executes the offset time setting process.

[0114] In the process of step S34, the processing device 21 transmits the data taking the offset time into consideration. The processing device 21 starts transmitting the second data 42 after the offset time set in the process of step S33 has elapsed.

[0115] The processing device 21 that has transmitted the second data 42 ends this series of processes. The processing device 51 of the management device 50 also executes the series of processes shown in Fig. 11 in the same manner as the processing device 11. The processing device 51 executes the series of processes shown in Fig. 11 when it does not sense the start signal 40 for a predetermined time.

[0116] 11 , when this series of processes starts, in the process of step S31, the processing device 51 transitions to the second communication method. At this time, the processing device 51 switches the flag that determines the communication method of the management device 50 from the flag for the first communication method to the flag for the second communication method. As a result, the communication method of the management device 50 transitions from the first communication method to the second communication method. In this way, the management device 50 switches the communication method from the first communication method to the second communication method.

[0117] In the next step S32, the processing device 51 determines whether there is data to be transmitted. The processing device 51 determines whether there is data to be transmitted based on whether the management device 50 needs to transmit the third data 43.

[0118] In the process of step S32, if the processing device 51 determines that there is no data to transmit (step S32: NO), the processing device 51 ends this series of processes. In the process of step S32, if the processing device 51 determines that there is data to transmit (step S32: YES), the processing device 51 proceeds to the process of step S33. In the process of step S33, the processing device 51 executes the offset time setting process.

[0119] In the process of step S34, the processing device 51 transmits the data taking the offset time into consideration. The processing device 51 starts transmitting the third data 43 after the offset time set in the process of step S33 has elapsed.

[0120] The processing device 51, which has transmitted the third data 43, ends this series of processes. <Processing When the Management Device 50 Switches the Communication Method to the First Communication Method> Fig. 12 shows the flow of a series of processes when the management device 50 switches the communication methods of multiple communication devices to the first communication method. This series of processes is executed by the processing device 51 of the management device 50. The processing device 51 executes this series of processes after transitioning the communication method to the second communication method in the process of step S31 in Fig. 11. This process corresponds to the process executed by the management device 50 shown in the lower part of Fig. 8.

[0121] 12, when this series of processes starts, in the process of step S41, the processing device 51 determines whether or not a state in which no data is transmitted has continued for a certain period of time. That is, the processing device 51 determines whether or not a state in which no data is transmitted among the first communication device 10, the second communication device 20, and the management device 50 via the second communication method has continued for a certain period of time.

[0122] In the process of step S41, if the processor 51 determines that the state in which data is not transmitted has not continued for a certain period of time (step S41: NO), it repeats the process of step S41.

[0123] In the process of step S41, if the processing device 51 determines that a state in which data is not transmitted has continued for a certain period of time (step S41: YES), the processing device 51 proceeds to the process of step S42. In the process of step S42, the processing device 51 transmits the start signal 40.

[0124] In the processing of step S43, the processing device 51 transitions the communication method of the management device 50 to the first communication method. At this time, the processing device 51 switches the flag that determines the communication method of the management device 50 from the flag for the second communication method to the flag for the first communication method. As a result, the communication method of the management device 50 transitions from the second communication method to the first communication method. In this way, the management device 50 returns the communication method from the second communication method to the first communication method.

[0125] The processing device 51, which has switched the communication method to the first communication method, ends this series of processes. Note that, as a result of the processing device 51 transmitting the start signal 40 in the process of step S42, the first communication device 10 and the second communication device 20 that received the start signal 40 switch the flag that determines the communication method from the flag for the second communication method to the flag for the first communication method, as shown in the lower part of FIG. 8 . As a result, the communication methods of the first communication device 10 and the second communication device 20 switch from the second communication method to the first communication method. In this way, the first communication device 10 and the second communication device 20 return the communication method from the second communication method to the first communication method.

[0126] <Operation of the Present Embodiment> In the communication network system 100 and the vehicle 101 equipped with the communication network system 100, the jamming device transmits a jamming signal in response to a communication error situation, thereby jamming the plurality of communication devices from sensing the start signal 40. As a result, the communication method of each communication device is switched from the first communication method to the second communication method.

[0127] <Advantages of the Present Embodiment> (1) In the first communication method, each communication device transmits data in a predetermined order. On the other hand, in the second communication method, each communication device can transmit data regardless of the predetermined order. Therefore, the communication network system 100 and the vehicle 101 equipped with the communication network system 100 can suppress communication errors occurring in a specific communication device among the multiple communication devices.

[0128] (2) The jamming device acquires the status of a communication error in the communication network system 100. Then, the jamming device transmits a jamming signal based on the acquired status of the communication error. In the communication network system 100, the jamming device transmits a jamming signal based on the acquired status of the communication error. This allows the communication network system 100 to switch the communication method of each communication device to the second communication method in response to the status of the communication error.

[0129] (3) The communication network system 100 is mounted on a vehicle 101. The jamming device grasps the status of the vehicle 101. Then, the jamming device transmits a jamming signal based on the acquired status of the communication error and the grasped status of the vehicle 101.

[0130] In the second communication method, each communication device can transmit data regardless of a predetermined order. However, when one communication device is transmitting data, the other communication devices cannot transmit data. In other words, in the second communication method, each communication device is not guaranteed an opportunity to transmit data. Therefore, depending on the situation of the vehicle 101, switching the communication method of each communication device in the communication network system 100 may cause a specific communication device to be unable to transmit data for a long period of time.

[0131] In the communication network system 100, the jamming device determines whether to transmit a jamming signal depending on the situation of the vehicle 101. In this way, the communication network system 100 can prioritize securing an opportunity to transmit data by not transmitting a jamming signal depending on the situation of the vehicle 101.

[0132] (4) The jamming device acquires, as the communication error status, information on the number of communication errors that occurred while at least one of the communication devices transmitted data a predetermined number of times. In the communication network system 100, the jamming device acquires, as the communication error status, information on the frequency of communication errors in each communication device. This allows the communication network system 100 to switch the communication method of each communication device to the second communication method according to the frequency of communication errors in each communication device.

[0133] (5) The jamming device transmits a jamming signal when the acquired number of communication errors is equal to or greater than a predetermined value. In the communication network system 100, the jamming device transmits a jamming signal when the number of communication errors is equal to or greater than a predetermined value. This allows the communication network system 100 to switch the communication method of the multiple communication devices to the second communication method when the frequency of communication errors is equal to or greater than a predetermined frequency.

[0134] (6) In the communication network system 100, a predetermined value is set for each communication device. The jamming device transmits a jamming signal when the number of communication errors for any of the communication devices among the plurality of communication devices exceeds the predetermined value.

[0135] In the above-described communication network system 100, the jamming device transmits a jamming signal when the number of communication errors of any of the plurality of communication devices is equal to or greater than a corresponding predetermined value, thereby enabling the communication network system 100 to switch the communication method of each communication device while closely monitoring the communication error status of each communication device.

[0136] (7) The jamming device does not transmit a jamming signal when the grasped status of the vehicle 101 indicates that the vehicle 101 is in autonomous driving. When the vehicle 101 is in autonomous driving, it is desirable that each communication device communicates using a first communication method that guarantees an opportunity to transmit data. In the communication network system 100, the jamming device does not transmit a jamming signal when the vehicle 101 is in autonomous driving. In other words, in the communication network system 100, the communication method of the multiple communication devices is not switched to the second communication method when the vehicle 101 is in autonomous driving. This allows the communication network system 100 to guarantee an opportunity for communication by each communication device. In other words, the communication network system 100 can prevent the execution of autonomous driving by the vehicle 101 from being hindered by switching the communication method of the multiple communication devices to the second communication method.

[0137] (8) The jamming device is configured not to transmit a jamming signal when the grasped status of the vehicle 101 is that the vehicle 101 is undergoing a fault diagnosis. When the vehicle 101 is undergoing a fault diagnosis, it is desirable that each communication device communicates using a first communication method that guarantees an opportunity to transmit data. In the communication network system 100, the jamming device does not transmit a jamming signal when the vehicle 101 is undergoing a fault diagnosis. In other words, in the communication network system 100, the communication method of the multiple communication devices is not switched to the second communication method when the vehicle 101 is undergoing a fault diagnosis. This allows the communication network system 100 to guarantee an opportunity for each communication device to communicate. In other words, the communication network system 100 can prevent the execution of the fault diagnosis by the vehicle 101 from being hindered by switching the communication method of the multiple communication devices to the second communication method.

[0138] (9) The jamming device is applied to a communication network system 100. The communication network system 100 includes a plurality of communication devices and a management device 50 that transmits a start signal 40 to the plurality of communication devices. The plurality of communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order after detecting the start signal 40. The plurality of communication devices are configured to switch the communication method to a second communication method in which each communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order, when a state in which the start signal 40 is not detected continues for a predetermined time. The jamming device transmits a jamming signal that interferes with the detection of the start signal 40 by the plurality of communication devices, depending on the status of a communication error in the communication network system 100.

[0139] The jamming device transmits a jamming signal in response to a communication error, thereby disrupting the detection of the start signal 40 by the plurality of communication devices in the communication network system 100, and causing the communication method of the plurality of communication devices to switch from the first communication method to the second communication method.

[0140] In the first communication method, each communication device transmits data in a predetermined order, whereas in the second communication method, each communication device can transmit data in any order regardless of the predetermined order.

[0141] In this manner, the jamming device can suppress communication errors occurring in a specific communication device among the plurality of communication devices. (10) When the plurality of communication devices switch the communication method from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, the plurality of communication devices sets an offset time, which is the time from the point at which the communication method is switched to the second communication method to the point at which data transmission starts. Then, the communication device starts transmitting the data when the set offset time has elapsed.

[0142] In the second communication method, the order in which each communication device transmits data is not determined as in the first communication method, so immediately after multiple communication devices switch their communication method to the second communication method, the multiple communication devices may start transmitting data simultaneously, which may result in data collisions.

[0143] In the communication network system 100, the communication devices that have switched the communication method to the second communication method start transmitting data after the offset time set by each communication device has elapsed. This allows the communication network system 100 to suppress data collisions immediately after the communication devices switch the communication method to the second communication method.

[0144] (11) When switching from a first communication method to a second communication method, if each of a plurality of communication devices has data to transmit immediately after switching to the second communication method, the communication device sets an offset time, which is the time from when the communication method is switched to the second communication method to when data transmission starts. The communication device sets the offset time so that it becomes shorter as the amount of data to be transmitted increases. The communication device starts transmitting data when the set offset time has elapsed.

[0145] In the communication network system 100, each of the communication devices that have switched their communication method to the second communication method starts transmitting data after an offset time set based on the amount of data to be transmitted has elapsed. As a result, when the communication network system 100 has switched its communication method to the second communication method, it is possible for large-volume data to be preferentially transmitted while suppressing collisions between data.

[0146] (12) Priorities are set in advance for a plurality of communication devices. When switching from a first communication method to a second communication method, if each of the plurality of communication devices has data to transmit immediately after switching to the second communication method, the communication device sets an offset time, which is the time from when the communication method is switched to the second communication method to when data transmission starts. The communication device sets the offset time so that the higher the priority, the shorter the offset time. The communication device starts transmitting data when the set offset time has elapsed.

[0147] In the communication network system 100, a plurality of communication devices that have switched their communication method to the second communication method start transmitting data after an offset time set by each communication device based on a predetermined priority has elapsed. As a result, when a plurality of communication devices have switched their communication method to the second communication method, the communication network system 100 can cause a communication device with a higher priority to transmit data preferentially while suppressing collisions between data.

[0148] (13) A program is applied to a jamming device of a communication network system 100. The communication network system 100 includes a plurality of communication devices and a management device 50 that transmits a start signal 40. After detecting the start signal 40, the plurality of communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order. If a state in which the start signal 40 is not detected continues for a predetermined time, the plurality of communication devices are configured to switch the communication method to a second communication method in which each communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order. The program causes the jamming device to transmit a jamming signal that jams the plurality of communication devices from detecting the start signal 40, based on a communication error status in the communication network system 100.

[0149] The program causes the jamming device to transmit a jamming signal in response to a communication error, thereby disrupting the detection of the start signal 40 by the plurality of communication devices in the communication network system 100, and causing the communication method of the plurality of communication devices to switch from the first communication method to the second communication method.

[0150] In the first communication method, each communication device transmits data in a predetermined order, whereas in the second communication method, each communication device can transmit data in any order regardless of the predetermined order.

[0151] This allows the program to suppress communication errors that occur in a specific communication device among the multiple communication devices. In the above embodiment, the program is stored in the storage device 12 of the first communication device 10. This program may be provided in a state recorded on a recording medium. The recording medium on which the program is recorded is, for example, a memory such as a USB memory, an SSD, or an SD card, or a CD-ROM, an optical disk, or the like.

[0152] (14) A communication method is applied to a communication network system 100. The communication method includes a step in which a management device 50 transmits a start signal 40, and a step in which a plurality of communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order after detecting the start signal 40. The communication method includes a step (step S104) in which a jamming device transmits a jamming signal based on a communication error situation in the communication network system 100. The communication method includes a step (step S31) in which, when a state in which the plurality of communication devices do not detect the start signal 40 continues for a predetermined time, each communication device switches the communication method to a second communication method in which each communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order.

[0153] In the communication network system 100, the communication method causes the jamming device to transmit a jamming signal in response to a communication error situation, thereby jamming the detection of the start signal 40 by the multiple communication devices in the communication network system 100, and switching the communication method of the multiple communication devices from the first communication method to the second communication method.

[0154] In the first communication method, each communication device transmits data in a predetermined order, whereas in the second communication method, each communication device can transmit data in any order regardless of the predetermined order.

[0155] As a result, the communication method can suppress communication errors that occur in a specific communication device among a plurality of communication devices. <Modifications> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be implemented in combination with each other to the extent that there is no technical contradiction.

[0156] In the above embodiment, the management device 50 transmits the third data 43. The management device 50 does not need to also function as a communication device that transmits data. In other words, the management device 50 only needs to be a device that transmits the start signal 40, and does not need to also function as a communication device that transmits the third data 43 after the start signal 40 is transmitted in the first communication method. In this case, the management device 50 does not need to also function as a communication device that transmits the third data 43 in the second communication method.

[0157] In the above embodiment, the first communication device 10 transmits the first data 41. On the other hand, the jamming device does not need to also function as a communication device that transmits data. In other words, the first communication device 10 functioning as a jamming device in the above embodiment only needs to be a device that transmits a jamming signal, and does not need to also function as a communication device that transmits the first data 41 after the start signal 40 is transmitted in the first communication method. In this case, the first communication device 10 does not need to also function as a communication device that transmits the first data 41 in the second communication method.

[0158] In the above embodiment, the communication devices in the communication network system 100 are connected by wire via the communication bus 30. However, the communication devices in the communication network system 100 may be connected wirelessly.

[0159] In the above embodiment, the first communication device 10 acquires the communication error status for all communication devices in the communication network system 100. On the other hand, the first communication device 10 may acquire the communication error status for only a specific communication device among the multiple communication devices.

[0160] In the above embodiment, the default value is set for each communication device. However, in the communication network system 100, the default value may be common to a plurality of communication devices. In the communication network system 100, the default value may be common to all communication devices.

[0161] In the present embodiment, the first communication device 10 acquires the communication error status for each communication device in the communication network system 100. However, the first communication device 10 may acquire the communication error status for the entire communication network system 100.

[0162] In this case, the jamming device is configured to acquire, as the communication error status, information on the number of communication errors that occurred during a predetermined number of data transmissions in the communication network system 100. In the communication network system 100, the jamming device acquires, as the communication error status, information on the frequency of communication errors occurring throughout the communication network system 100. This enables the communication network system 100 to switch the communication methods of the multiple communication devices to the second communication method depending on the frequency of communication errors occurring in data transmitted through the communication network system 100.

[0163] In this case, one default value is set for the entire communication network system 100, not for each communication device. In this embodiment, the first communication device 10 transmits a jamming signal based on the communication error status that it has acquired. On the other hand, the first communication device 10 may transmit a jamming signal based on a request from another communication device that has acquired the communication error status, rather than acquiring the communication error status by itself.

[0164] 13 shows a specific example of communication when the first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the first modified example switch the communication method to the second communication method. The first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the first modified example execute the communication shown in FIG. 13 instead of the communication shown in FIG. 8.

[0165] The communication shown in Fig. 13 is performed when the same two conditions as those in Fig. 8 are met. When the two conditions are met, as shown in the upper part of Fig. 13, the second communication device 20 transmits a jamming request signal to the first communication device 10, which is a jamming device. The jamming request signal is a signal that requests the jamming device to transmit a jamming signal. In this way, in the first modified example, the second communication device 20 is a jamming request device that transmits a jamming request signal depending on the status of a communication error.

[0166] 13 , after receiving the jamming request signal, the first communication device 10 transmits a jamming signal at the same timing as the management device 50 transmits the start signal 40. As a result, the first communication device 10, the second communication device 20, and the management device 50 do not sense the start signal 40.

[0167] The communication state after the first communication device 10 transmits the jamming signal is the same as in Fig. 8 . In the first modified example, the second communication device 20 acquires the status of communication errors in the communication network system 100 in order to transmit a jamming request signal as necessary. At this time, the second communication device 20 acquires, as the status of communication errors, information on the number of communication errors that occurred while each communication device transmitted data a predetermined number of times, similar to the first communication device 10 in the above embodiment. Also, in the first modified example, a default value is set for each communication device, similar to the above embodiment.

[0168] 14 shows a series of processes executed by the second communication device 20 when transmitting a jamming request signal. This series of processes is executed by the processing device 21 of the second communication device 20. This series of processes is executed when the second communication device 20 acquires information on the number of communication errors that occurred during a predetermined number of data transmissions from any of the first communication device 10, the second communication device 20, and the management device 50.

[0169] 14, when this series of processes is started, in the process of step S111, the processing device 21 determines whether the number of communication errors in the communication device from which the information was obtained is equal to or greater than a predetermined value. This process is the same as the process executed by the processing device 11 in step S101 of FIG.

[0170] In the process of step S111, if the processing device 21 determines that the number of communication errors is not equal to or greater than the predetermined value (step S111: NO), the processing device 21 ends this series of processes. In the process of step S111, if the processing device 21 determines that the number of communication errors is equal to or greater than the predetermined value (step S111: YES), the processing device 21 proceeds to the process of step S112.

[0171] In the process of step S112, the processing device 21 grasps the situation of the vehicle 101. This process is the same as the process executed by the processing device 11 in step S102 of FIG. 10. In the process of step S113, the processing device 21 determines whether or not the multiple communication devices in the communication network system 100 are capable of switching to the second communication method. This process is the same as the process executed by the processing device 11 in step S103 of FIG. 10. For example, when the vehicle 101 is in autonomous driving, the processing device 21 determines that the multiple communication devices are not capable of switching to the second communication method. Furthermore, for example, when the vehicle 101 is undergoing a fault diagnosis, the processing device 21 determines that the multiple communication devices are not capable of switching to the second communication method.

[0172] In the process of step S113, if the processor 21 determines that the plurality of communication devices are not capable of switching to the second communication method (step S113: NO), the processor 21 ends this series of processes.

[0173] In the process of step S113, if the processor 21 determines that a plurality of communication devices can switch to the second communication method (step S113: YES), the processor 21 proceeds to the process of step S114.

[0174] In the process of step S114, the processing device 21 transmits an interference request signal. At this time, the processing device 21 transmits the interference request signal in accordance with the first communication method. This process corresponds to the process executed by the second communication device 20 in the upper part of Fig. 13. In this way, the processing device 21 transmits the interference request signal based on the acquired communication error status and the understood status of the vehicle 101.

[0175] Upon receiving the jamming request signal, the first communication device 10 transmits a jamming signal in response to the jamming request signal, instead of the series of processes shown in Fig. 10. In this way, the communication network system 100 of the first modified example further includes a jamming request device that transmits a jamming request signal requesting the jamming device to transmit a jamming signal. The jamming request device acquires the status of communication errors in the communication network system 100. The jamming request device transmits the jamming request signal based on the acquired status of communication errors. The jamming device transmits the jamming signal when it receives the jamming request signal.

[0176] In the communication network system 100 of the first modification, the interference request device causes the interference device to transmit a interference signal in accordance with the acquired communication error status, thereby enabling the communication network system 100 of the first modification to switch the communication method of the plurality of communication devices to the second communication method in accordance with the communication error status.

[0177] The communication network system 100 of the first modified example is mounted on a vehicle 101. The interference request device grasps the status of the vehicle 101. The interference request device transmits an interference request signal based on the acquired communication error status and the grasped status of the vehicle 101.

[0178] In the communication network system 100 of the first modified example, the interference request device determines whether to transmit an interference request signal depending on the situation of the vehicle 101. In this way, the communication network system can prioritize securing an opportunity to transmit data by not transmitting an interference request signal depending on the situation of the vehicle 101.

[0179] In the first modified example of the communication network system 100, the interference request device acquires, as the communication error status, information on the number of communication errors that occurred while at least one of the multiple communication devices transmitted data a predetermined number of times.

[0180] In the communication network system 100 of the first modified example, the interference request device acquires information about the frequency of communication errors in each communication device as the communication error status. This allows the communication network system 100 of the first modified example to switch the communication method of the multiple communication devices to the second communication method depending on the frequency of communication errors in each communication device.

[0181] In the communication network system 100 of the first modified example, the interference request device transmits an interference request signal when the acquired number of communication errors is equal to or greater than a predetermined value. In the communication network system 100 of the first modified example, the interference request device transmits an interference request signal when the number of communication errors is equal to or greater than a predetermined value. This allows the communication network system 100 of the first modified example to switch the communication method of the multiple communication devices to the second communication method when the frequency of communication errors is equal to or greater than a predetermined frequency.

[0182] In the first modification, a predetermined value is set for each communication device, and the interference request device transmits an interference request signal when the number of communication errors for any of the plurality of communication devices reaches or exceeds the predetermined value.

[0183] In the communication network system 100 of the first modification, the interference request device transmits an interference request signal when the number of communication errors of any of the communication devices is equal to or greater than a corresponding predetermined value. This allows the communication network system 100 of the first modification to switch the communication method of the plurality of communication devices to the second communication method while closely monitoring the communication error status of each communication device.

[0184] In the communication network system 100 of the first modified example, the interference request device does not transmit an interference request signal when the grasped status of the vehicle 101 is that the vehicle 101 is in autonomous driving. In other words, in the communication network system 100 of the first modified example, the communication methods of the multiple communication devices are not switched to the second communication method when the vehicle 101 is in autonomous driving. This allows the communication network system 100 of the first modified example to guarantee communication opportunities for each communication device. In other words, the communication network system 100 of the first modified example can prevent the execution of autonomous driving by the vehicle 101 from being hindered by switching the communication methods of the multiple communication devices to the second communication method.

[0185] In the communication network system 100 of the first modified example, the interference request device is configured not to transmit an interference request signal when the grasped status of the vehicle 101 is that the vehicle 101 is undergoing a fault diagnosis. In other words, in the communication network system 100 of the first modified example, the communication methods of the multiple communication devices are not switched to the second communication method when the vehicle 101 is undergoing a fault diagnosis. This allows the communication network system 100 of the first modified example to guarantee communication opportunities for each communication device. In other words, the communication network system 100 of the first modified example can prevent the execution of the fault diagnosis by the vehicle 101 from being hindered by switching the communication methods of the multiple communication devices to the second communication method.

[0186] In the first modified example, the second communication device 20 acquires the communication error status for all communication devices in the communication network system 100. On the other hand, the second communication device 20 may acquire the communication error status for only a specific communication device.

[0187] In the first modified example, the second communication device 20 acquires the communication error status for each communication device in the communication network system 100. On the other hand, the second communication device 20 may acquire the communication error status for the entire communication network system 100.

[0188] In this case, the interference request device acquires, as the communication error status, information on the number of communication errors that occurred while data was transmitted a predetermined number of times in the communication network system 100 of the first modified example. In the communication network system 100 of the first modified example, the interference request device acquires, as the communication error status, information on the frequency of communication errors occurring in the entire communication network system 100. In this way, the communication network system 100 of the first modified example can switch the communication method of the multiple communication devices to the second communication method depending on the frequency of communication errors occurring in data transmitted in the communication network system 100.

[0189] In the first modified example, the second communication device 20, which is a jamming request device, transmits a jamming request signal based on the acquired communication error status and the grasped status of the vehicle 101. On the other hand, the second communication device 20 may transmit a jamming request signal based only on the acquired communication error status without grasping the status of the vehicle 101. In this case, the first communication device 10, which is a jamming device that has received the jamming request signal, grasps the status of the vehicle 101 and then transmits a jamming signal based on the status of the vehicle 101.

[0190] 15 shows a specific example of communication when the first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the second modified example switch the communication method to the second communication method. The first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the second modified example execute the communication shown in FIG. 15 instead of the communication shown in FIG. 8.

[0191] In the communication shown in Figure 15, the second communication device 20 transmits an interference request signal to the first communication device 10 when the number of communication errors that occur while any communication device in the communication network system 100 transmits data a predetermined number of times exceeds a predetermined value.

[0192] When the first communication device 10 receives the jamming request signal and the plurality of communication devices are able to switch to the second communication method, the first communication device 10 transmits a jamming signal at the timing when the management device 50 transmits the start signal 40. As a result, the first communication device 10, the second communication device 20, and the management device 50 do not sense the start signal 40.

[0193] The communication state after the first communication device 10 transmits the jamming signal is the same as that shown in Fig. 8. Fig. 16 shows a series of processes executed by the second communication device 20 when transmitting a jamming request signal. This series of processes is executed by the processing device 21 of the second communication device 20. This series of processes is executed when the second communication device 20 acquires information on the number of communication errors that occurred during a predetermined number of data transmissions from any of the first communication device 10, the second communication device 20, and the management device 50.

[0194] 16, when this series of processes is started, in the process of step S121, the processing device 21 determines whether the number of communication errors in the communication device from which the information was obtained is equal to or greater than a predetermined value. This process is similar to the process executed by the processing device 11 in step S101 of FIG.

[0195] In the process of step S121, if the processing device 21 determines that the number of communication errors is not equal to or greater than a predetermined value (step S121: NO), the processing device 21 ends this series of processes. In the process of step S121, if the processing device 21 determines that the number of communication errors is equal to or greater than a predetermined value (step S121: YES), the processing device 21 proceeds to the process of step S122. In the process of step S122, the processing device 21 transmits a jamming request signal. At this time, the processing device 21 transmits the jamming request signal according to the first communication method. This process corresponds to the process executed by the second communication device 20 in the upper part of FIG. 15 .

[0196] Fig. 17 shows a series of processing flows when the first communication device 10 transmits a jamming signal. This series of processing flows is executed by the processing device 11 of the first communication device 10. The processing device 11 transmits the jamming signal by executing the series of processing flows shown in Fig. 17 instead of the series of flows shown in Fig. 10. This series of processing flows is executed when the first communication device 10 receives a jamming request signal.

[0197] 17, when this series of processes is started, in the process of step S131, the processing device 11 grasps the situation of the vehicle 101. This process is similar to the process of step S102 in FIG.

[0198] In the next step S132, the processing device 11 determines whether or not the plurality of communication devices in the communication network system 100 are capable of switching to the second communication method. This step is similar to the step S103 in FIG.

[0199] In the process of step S132, if the processing device 11 determines that the plurality of communication devices cannot switch to the second communication method (step S132: NO), the processing device 11 ends this series of processes.

[0200] In the process of step S132, if the processing device 11 determines that the plurality of communication devices can switch to the second communication method (step S132: YES), the processing device 11 proceeds to the process of step S133. In the process of step S133, the processing device 11 transmits a jamming signal. This process corresponds to the process executed by the first communication device 10 in the upper part of FIG. 15 .

[0201] The communication network system 100 of the second modified example is mounted on a vehicle 101. The jamming device grasps the situation of the vehicle 101. When the jamming device receives a jamming request signal, the jamming device transmits a jamming signal based on the grasped situation of the vehicle 101.

[0202] In the communication network system 100 of the second modified example, when the jamming device receives a jamming request signal, the jamming device determines whether to transmit a jamming signal depending on the situation of the vehicle 101. In this way, the communication network system 100 of the second modified example can prioritize securing an opportunity to transmit data by not transmitting a jamming signal depending on the situation of the vehicle 101.

[0203] In the above embodiment, the first communication device 10 in the communication network system 100 switches the communication method of the plurality of communication devices to the second communication method by transmitting a jamming signal. On the other hand, the management device 50 in the communication network system 100 may switch the communication method of the plurality of communication devices to the second communication method by stopping transmission of the start signal 40.

[0204] 18 shows a specific example of communication when the first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the third modified example switch the communication method to the second communication method. The first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the third modified example execute the communication shown in FIG. 18 instead of the communication mode shown in FIG.

[0205] The communication shown in Fig. 18 is executed when the same two conditions as in Fig. 8 are met. When the two conditions are met, the management device 50 stops transmitting the start signal 40, as shown in the upper part of Fig. 18. As a result, the first communication device 10, the second communication device 20, and the management device 50 no longer sense the start signal 40.

[0206] 18, the first communication device 10, the second communication device 20, and the management device 50 switch to the second communication method when a state in which they do not sense a start signal continues for a predetermined time. In this way, each communication device in the communication network system 100 of the third modified example switches the communication method from the first communication method to the second communication method.

[0207] The communication mode after the communication device transitions to the second communication method is the same as that shown in Fig. 8. Note that in the third modified example, the first communication device 10 does not need to be a jamming device. Therefore, in the third modified example, the first communication device 10 does not execute the series of processes shown in Fig. 10.

[0208] In the third modified example, the management device 50 acquires the status of communication errors in the communication network system 100 instead of the first communication device 10 in order to stop the transmission of the start signal 40 as necessary. At this time, the management device 50 acquires, as the status of communication errors, information on the number of communication errors that occurred while each communication device transmitted data a predetermined number of times, similar to the first communication device 10 in the above embodiment. Also, in the third modified example, similar to the present embodiment, a default value is set for each communication device.

[0209] 19 shows a series of processes executed by the management device 50 when the management device 50 stops transmitting the start signal 40. The program stored in the storage device 52 of the management device 50 includes a program for controlling the communication methods of the multiple communication devices in the communication network system 100 of the third modified example. This series of processes is executed by the processing device 51 of the management device 50 performing processing in accordance with the program stored in the storage device 52. This series of processes is executed when the management device 50 acquires information on the number of communication errors that occurred during a predetermined number of data transmissions for any of the first communication device 10, the second communication device 20, and the management device 50.

[0210] 19, when this series of processes is started, in the process of step S141, the processing device 51 determines whether the number of communication errors in the communication device from which the information was obtained is equal to or greater than a predetermined value. This process is similar to the process executed by the processing device 11 in step S101 of FIG.

[0211] In the process of step S141, if the processor 51 determines that the number of communication errors is not equal to or greater than the predetermined value (step S141: NO), the processor 51 ends this series of processes. In the process of step S141, if the processor 51 determines that the number of communication errors is equal to or greater than the predetermined value (step S141: YES), the processor 51 proceeds to the process of step S142.

[0212] In the processing of step S142, the processing device 51 grasps the status of the vehicle 101. This processing is similar to the processing executed by the processing device 11 in step S102 of FIG. 10. In the processing of the next step S143, the processing device 51 determines whether or not the multiple communication devices in the communication network system 100 of the third modified example are capable of transitioning to the second communication method. This processing is similar to the processing executed by the processing device 11 in step S103 of FIG. 10. Therefore, for example, when the vehicle 101 is in an autonomous driving state, the processing device 51 determines that the multiple communication devices are not capable of transitioning to the second communication method. Furthermore, for example, when the vehicle 101 is in a fault diagnosis state, the processing device 51 determines that the multiple communication devices are not capable of transitioning to the second communication method.

[0213] In the process of step S143, if the processor 51 determines that the plurality of communication devices are not capable of switching to the second communication method (step S143: NO), the processor 51 ends this series of processes.

[0214] In the process of step S143, if the processing device 51 determines that the plurality of communication devices can switch to the second communication method (step S143: YES), the processing device 51 proceeds to the process of step S144. In the process of step S144, the processing device 51 stops transmitting the start signal 40. This process corresponds to the process executed by the management device 50 in the upper part of FIG. 18 . In this way, the processing device 51 stops transmitting the start signal 40 based on the acquired communication error status and the grasped status of the vehicle 101.

[0215] A communication network system 100 according to a third modified example and a vehicle 101 equipped with the communication network system 100 according to the third modified example include a plurality of communication devices and a management device 50 that transmits a start signal 40 to the plurality of communication devices. The plurality of communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order after detecting the start signal 40. The management device 50 stops transmitting the start signal 40 depending on the status of a communication error in the communication network system 100 according to the third modified example. If the state in which the start signal 40 is not detected continues for a predetermined time, the plurality of communication devices switch their communication method to a second communication method in which each communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order.

[0216] In the communication network system 100 of the third modified example and the vehicle 101 equipped with the communication network system 100, the management device 50 stops transmitting the start signal 40 depending on the state of the communication error. As a result, in the communication network system 100 of the third modified example and the vehicle 101 equipped with the communication network system 100, the communication method of the multiple communication devices is switched from the first communication method to the second communication method.

[0217] In the first communication method, each communication device transmits data in a predetermined order. On the other hand, in the second communication method, each communication device can transmit data regardless of the predetermined order. As a result, the communication network system 100 of the third modified example and the vehicle 101 equipped with the communication network system 100 can suppress communication errors occurring in a specific communication device among the multiple communication devices.

[0218] The management device 50 acquires the status of the communication error in the communication network system 100 of the third modified example. The management device 50 stops transmitting the start signal 40 based on the acquired status of the communication error.

[0219] In the communication network system 100 of the third modified example, the management device 50 stops transmitting the start signal based on the communication error status acquired by the management device 50. This allows the communication network system 100 of the third modified example to switch the communication method of each communication device to the second communication method in response to the communication error status.

[0220] The communication network system 100 of the third modified example is mounted on a vehicle 101. The management device 50 grasps the status of the vehicle 101. The management device 50 stops transmission of the start signal 40 based on the acquired communication error status and the grasped status of the vehicle 101.

[0221] In the communication network system 100 of the third modified example, the management device 50 determines whether or not to stop transmission of the start signal depending on the status of the vehicle 101. In this way, the communication network system 100 of the third modified example can prioritize ensuring opportunities to transmit data by not stopping the start signal 40 depending on the status of the vehicle 101.

[0222] In the communication network system 100 of the third modified example, the management device 50 acquires, as the communication error status, information on the number of communication errors that occurred while at least one of the multiple communication devices transmitted data a predetermined number of times. In the communication network system 100 of the third modified example, the management device 50 acquires, as the communication error status, information on the frequency of communication errors in each communication device. This allows the communication network system 100 of the third modified example to switch the communication method of the communication device to the second communication method depending on the frequency of communication errors in each communication device.

[0223] In the communication network system 100 of the third modified example, the management device 50 stops transmitting the start signal 40 when the acquired number of communication errors is equal to or greater than a predetermined value. This allows the communication network system 100 of the third modified example to switch the communication method to the second communication method when the frequency of occurrence of communication errors is equal to or greater than a predetermined frequency.

[0224] In the communication network system 100 of the third modified example, the management device 50 stops transmitting the start signal 40 when the number of communication errors for any of the communication devices among the plurality of communication devices becomes equal to or exceeds the predetermined value.

[0225] In the communication network system 100 of the third modified example, the management device 50 stops transmitting the start signal when the number of communication errors of any of the plurality of communication devices is equal to or greater than a corresponding predetermined value. This allows the communication network system 100 of the third modified example to switch the communication method of the plurality of communication devices to the second communication method while closely monitoring the communication error status of each communication device.

[0226] In the communication network system 100 of the third modified example, the management device 50 does not stop transmitting the start signal when the status of the vehicle 101 that is grasped is that the vehicle 101 is in autonomous driving. In other words, in the communication network system 100 of the third modified example, the communication method is not switched to the second communication method when the vehicle 101 is in autonomous driving. This allows the communication network system 100 of the third modified example to guarantee communication opportunities for each communication device. In other words, the communication network system 100 of the third modified example can prevent the execution of autonomous driving by the vehicle 101 from being hindered by switching the communication methods of multiple communication devices to the second communication method.

[0227] In the communication network system 100 of the third modified example, the management device 50 does not stop transmitting the start signal 40 when the status of the vehicle 101 that is determined is that a fault diagnosis of the vehicle 101 is in progress. In other words, in the communication network system 100 of the third modified example, the communication method is not switched to the second communication method when the vehicle 101 is in the process of a fault diagnosis. This allows the communication network system 100 of the third modified example to guarantee communication opportunities for each communication device. In other words, the communication network system 100 of the third modified example can prevent the execution of a fault diagnosis by the vehicle 101 from being hindered by switching the communication methods of multiple communication devices to the second communication method.

[0228] A management device 50 transmits a start signal 40 in a communication network system 100 of a third modified example that includes a plurality of communication devices. The plurality of communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order after detecting the start signal 40. The plurality of communication devices are configured to switch the communication method to a second communication method in which each communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order, if a state in which the start signal 40 is not detected continues for a predetermined time. The management device 50 stops transmitting the start signal 40 depending on the status of a communication error in the communication network system 100 of the third modified example.

[0229] The management device 50 stops transmitting the start signal 40 depending on the state of the communication error. As a result, in the communication network system 100 of the third modified example, the communication method of the multiple communication devices is switched from the first communication method to the second communication method.

[0230] In the first communication method, each communication device transmits data in a predetermined order, whereas in the second communication method, each communication device can transmit data in any order regardless of the predetermined order.

[0231] This allows the management device 50 to suppress communication errors occurring in a specific communication device among the multiple communication devices. The program is applied to the management device 50 configured to transmit a start signal 40 in a communication network system 100 of a third modified example that includes multiple communication devices. The multiple communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order after detecting the start signal 40. On the other hand, if the multiple communication devices continue not to detect the start signal 40 for a predetermined period of time, the communication devices are configured to switch the communication method to a second communication method in which each communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order. The program causes the management device 50 to stop transmitting the start signal 40 based on the status of a communication error in the communication network system 100 of the third modified example.

[0232] The program causes the management device 50 to stop sending the start signal 40 depending on the state of the communication error. As a result, in the communication network system 100 of the third modified example, the communication method of the multiple communication devices is switched from the first communication method to the second communication method.

[0233] In the first communication method, each communication device transmits data in a predetermined order, whereas in the second communication method, each communication device can transmit data in any order regardless of the predetermined order.

[0234] This allows the program to suppress communication errors that occur in a specific communication device among multiple communication devices. In the above embodiment, the program is stored in the storage device 52 of the management device 50. The program may be provided in a state recorded on a recording medium. The recording medium on which the program is recorded may be a memory such as a USB memory, an SSD, or an SD card, a CD-ROM, an optical disk, or the like.

[0235] The communication method is a communication method in a communication network system 100 of a third modified example. The communication method includes a step in which a management device 50 transmits a start signal 40, and a step in which a plurality of communication devices communicate with each other using a first communication method in which each communication device transmits data in a predetermined order after detecting the start signal 40. The communication method includes a step (step S144) in which the management device 50 stops transmitting the start signal 40 based on a communication error status in the communication network system 100 of the third modified example. The communication method also includes a step (step S31) in which, when a state in which the plurality of communication devices do not detect the start signal 40 continues for a predetermined time, each communication device switches the communication method to a second communication method in which each communication device transmits data when other communication devices are not transmitting data, regardless of the predetermined order.

[0236] In the communication network system 100 of the third modified example, the communication method causes the management device 50 to stop transmitting the start signal 40 depending on the state of the communication error. As a result, in the communication network system 100 of the third modified example, the communication method of the multiple communication devices is switched from the first communication method to the second communication method.

[0237] In the first communication method, each communication device transmits data in a predetermined order, whereas in the second communication method, each communication device can transmit data in any order regardless of the predetermined order.

[0238] This makes it possible for the communication method to suppress communication errors occurring in a specific communication device among the multiple communication devices. In the third modified example, the management device 50 acquires the communication error status for all communication devices in the communication network system 100. On the other hand, the management device 50 may acquire the communication error status for only a specific communication device among the multiple communication devices.

[0239] In the third modified example, the management device 50 acquires the communication error status for each communication device in the communication network system 100. On the other hand, the management device 50 may acquire the communication error status for the entire communication network system 100.

[0240] In this case, the management device 50 acquires, as the status of the communication error, information on the number of communication errors that occurred while data was transmitted a predetermined number of times in the communication network system 100 of the third modified example.

[0241] In this case, in the communication network system 100 of the third modified example, the management device 50 acquires, as the communication error status, information on the frequency of occurrence of communication errors in the entire communication network system 100 of the third modified example. As a result, the communication network system 100 of the third modified example can switch the communication method of the multiple communication devices to the second communication method depending on the frequency of occurrence of communication errors in data transmitted by the communication network system 100 of the third modified example.

[0242] In the third modified example, the management device 50 stops transmitting the start signal 40 based on the communication error status that it has acquired. On the other hand, the management device 50 may stop transmitting the start signal 40 based on a request from another communication device that has acquired the communication error status, rather than acquiring the communication error status itself.

[0243] 20 shows a specific example of communication when the first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the fourth modified example switch the communication method to the second communication method. The first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the fourth modified example execute the communication shown in FIG. 20 instead of the communication mode shown in FIG. 8.

[0244] The communication shown in Fig. 20 is executed when the same two conditions as in Fig. 8 are met. When the two conditions are met, the first communication device 10 transmits a stop request signal to the management device 50, as shown in the upper part of Fig. 20. The stop request signal is a signal that requests the management device 50 to stop transmitting the start signal 40. In this way, in the fourth modified example, the first communication device 10 is a stop request device that transmits a stop request signal depending on the status of a communication error.

[0245] 20 , after receiving the stop request signal, the management device 50 stops transmitting the start signal 40. As a result, the first communication device 10, the second communication device 20, and the management device 50 no longer sense the start signal 40.

[0246] 20, the first communication device 10, the second communication device 20, and the management device 50 switch to the second communication method if they continue not to sense a start signal for a predetermined period of time. In this way, the multiple communication devices in the communication network system 100 of the fourth modified example switch their communication method to the second communication method.

[0247] The communication mode after the plurality of communication devices have switched to the second communication method is the same as that shown in Fig. 8. In the fourth modified example, as in the third modified example, the first communication device 10 does not need to be a jamming device. Therefore, in the fourth modified example, the first communication device 10 does not execute the series of processes shown in Fig. 10.

[0248] In the fourth modified example, the first communication device 10 acquires the status of communication errors in the communication network system 100 in order to transmit a stop request signal as necessary. At this time, as in the above embodiment, the first communication device 10 acquires information on the number of communication errors that occurred while each communication device transmitted data a predetermined number of times as the status of communication errors. Also, in the fourth modified example, as in the above embodiment, a default value is set for each communication device.

[0249] 21 shows a series of processes executed when the first communication device 10 transmits a stop request signal. This series of processes is executed by the processing device 11 of the first communication device 10. This series of processes is executed when the first communication device 10 acquires information on the number of communication errors that occurred during a predetermined number of data transmissions from the first communication device 10, the second communication device 20, or the management device 50.

[0250] 21, when this series of processes starts, in the process of step S151, the processing device 11 determines whether the number of communication errors in the communication device from which the information was obtained is equal to or greater than a predetermined value. This process is the same as the process of step S101 in FIG.

[0251] In the process of step S151, if the processing device 11 determines that the number of communication errors is not equal to or greater than the predetermined value (step S151: NO), the processing device 21 ends this series of processes. In the process of step S151, if the processing device 21 determines that the number of communication errors is equal to or greater than the predetermined value (step S151: YES), the processing device 21 proceeds to the process of step S152.

[0252] In the processing of step S152, the processing device 11 grasps the status of the vehicle 101. This processing is the same as the processing of step S102 in FIG. 10 . In the next processing of step S153, the processing device 11 determines whether or not the multiple communication devices in the communication network system 100 of the fourth modified example can switch to the second communication method. This processing is the same as the processing of step S103 in FIG. 10 . Therefore, for example, when the vehicle 101 is in an autonomous driving state, the processing device 11 determines that the multiple communication devices cannot switch to the second communication method. Furthermore, for example, when the vehicle 101 is in a fault diagnosis state, the processing device 21 determines that the multiple communication devices cannot switch to the second communication method.

[0253] In the process of step S153, if the processing device 11 determines that the plurality of communication devices cannot switch to the second communication method (step S153: NO), the processing device 11 ends this series of processes.

[0254] In the process of step S153, if the processing device 11 determines that the plurality of communication devices can switch to the second communication method (step S153: YES), the processing device 11 proceeds to the process of step S154. In the process of step S154, the processing device 11 transmits a stop request signal. At this time, the processing device 11 transmits the stop request signal according to the first communication method. This process corresponds to the process executed by the first communication device 10 in the upper part of FIG. 20. In this way, the processing device 11 transmits the stop request signal based on the acquired communication error status and the understood status of the vehicle 101.

[0255] Upon receiving the stop request signal, the management device 50 stops transmitting the start signal 40 in response to the stop request signal. The communication network system 100 of the fourth modified example further includes a stop request device that transmits a stop request signal to the management device 50 to request that the management device 50 stop transmitting the start signal 40. The stop request device acquires the status of communication errors in the communication network system 100 of the fourth modified example. The stop request device transmits the stop request signal based on the acquired status of communication errors. The management device 50 stops transmitting the start signal 40 upon receiving the stop request signal.

[0256] In the communication network system 100 of the fourth modified example, the stop request device causes the management device 50 to stop transmitting the start signal 40 in accordance with the acquired communication error status. This allows the communication network system 100 of the fourth modified example to switch the communication method of the multiple communication devices to the second communication method in accordance with the communication error status.

[0257] The communication network system 100 of the fourth modified example is mounted on a vehicle 101. The stop request device grasps the status of the vehicle 101. The stop request device transmits a stop request signal based on the acquired communication error status and the grasped status of the vehicle 101.

[0258] In the communication network system 100 of the fourth modified example, the stop request device determines whether to transmit a stop request signal depending on the situation of the vehicle 101. As a result, the communication network system 100 of the fourth modified example can prioritize securing an opportunity to transmit data by not transmitting a stop request signal depending on the situation of the vehicle 101.

[0259] In the communication network system 100 of the fourth modified example, the stop requesting device acquires, as the communication error status, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times. In the communication network system 100 of the fourth modified example, the stop requesting device acquires, as the communication error status, information on the frequency of communication errors in each communication device. This allows the communication network system 100 of the fourth modified example to switch the communication method of the communication device to the second communication method depending on the frequency of communication errors in each communication device.

[0260] In the communication network system 100 of the fourth modified example, the stop request device transmits a stop request signal when the acquired number of communication errors is equal to or greater than a predetermined value. In the communication network system 100 of the fourth modified example, the stop request device transmits a stop request signal when the number of communication errors is equal to or greater than a predetermined value. This allows the communication network system 100 of the fourth modified example to switch the communication method of the multiple communication devices to the second communication method when the frequency of communication errors is equal to or greater than a predetermined frequency.

[0261] A default value is set for each communication device. In the communication network system 100 of the fourth modified example, the stop request device transmits a stop request signal when the number of communication errors for any of the plurality of communication devices exceeds a default value. In the communication network system 100 of the fourth modified example, the stop request device transmits a stop request signal when the number of communication errors for any of the plurality of communication devices exceeds a corresponding default value. This allows the communication network system 100 of the fourth modified example to switch the communication methods of the plurality of communication devices to the second communication method while closely monitoring the communication error status of each communication device.

[0262] In the communication network system 100 of the fourth modified example, the stop request device does not transmit a stop request signal when the grasped status of the vehicle 101 is that the vehicle 101 is in autonomous driving. In other words, in the communication network system 100 of the fourth modified example, the communication methods of the multiple communication devices are not switched to the second communication method when the vehicle 101 is in autonomous driving. This allows the communication network system 100 of the fourth modified example to guarantee communication opportunities for each communication device. In other words, the communication network system 100 of the fourth modified example can prevent the execution of autonomous driving by the vehicle 101 from being hindered by switching the communication methods of the multiple communication devices to the second communication method.

[0263] In the communication network system 100 of the fourth modified example, the stop request device does not transmit a stop request signal when the status of the vehicle 101 that is determined is that the vehicle 101 is undergoing a fault diagnosis. In other words, in the communication network system 100 of the fourth modified example, the communication methods of the multiple communication devices are not switched to the second communication method when the vehicle 101 is undergoing a fault diagnosis. This allows the communication network system 100 of the fourth modified example to guarantee communication opportunities for each communication device. In other words, the communication network system 100 of the fourth modified example can prevent the execution of the fault diagnosis by the vehicle 101 from being hindered by switching the communication methods of the multiple communication devices to the second communication method.

[0264] In the fourth modified example, the first communication device 10 as the stop request device acquires the communication error status for all communication devices in the communication network system 100. On the other hand, the first communication device 10 may acquire the communication error status for only a specific communication device among the multiple communication devices.

[0265] In the fourth modified example, the first communication device 10 serving as the stop request device acquires the communication error status for each communication device in the communication network system 100. On the other hand, the first communication device 10 may acquire the communication error status for the entire communication network system 100.

[0266] In this case, the stop requesting device acquires, as the status of the communication error, information on the number of communication errors that occurred while data was transmitted a predetermined number of times in the communication network system 100 of the fourth modified example.

[0267] In this case, in the communication network system 100 of the fourth modified example, the stop request device acquires, as the communication error status, information about the frequency of communication errors occurring throughout the communication network system 100 of the fourth modified example. This allows the communication network system 100 of the fourth modified example to switch the communication method of the multiple communication devices to the second communication method depending on the frequency of communication errors occurring in data transmitted by the communication network system 100 of the fourth modified example.

[0268] In a fourth modified example, the first communication device 10 serving as the stop request device transmits an interference request signal based on the acquired communication error status and the grasped status of the vehicle 101. On the other hand, the first communication device 10 serving as the stop request device may transmit the stop request signal based only on the acquired communication error status without grasping the status of the vehicle 101. In this case, the management device 50 that receives the stop request signal grasps the status of the vehicle 101 and then stops transmitting the start signal 40 based on the status of the vehicle 101.

[0269] 22 shows a specific example of communication when the first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the fifth modified example switch the communication method to the second communication method. The first communication device 10, the second communication device 20, and the management device 50 in the communication network system 100 of the fifth modified example execute the communication shown in FIG. 22 instead of the communication mode shown in FIG. 8.

[0270] In the communication shown in Figure 22, the first communication device 10 sends a stop request signal to the management device 50 when the number of communication errors that occur while any communication device in the communication network system 100 transmits data a predetermined number of times exceeds a predetermined value.

[0271] When the management device 50 receives the stop request signal and, if the plurality of communication devices are able to switch to the second communication method, stops transmitting the start signal 40. As a result, the first communication device 10, the second communication device 20, and the management device 50 no longer sense the start signal 40.

[0272] 22, the first communication device 10, the second communication device 20, and the management device 50 switch to the second communication method when a state in which they do not sense a start signal continues for a predetermined time. In this way, the multiple communication devices in the communication network system 100 of the fifth modified example switch the communication method to the second communication method.

[0273] The communication mode after the plurality of communication devices have switched to the second communication method is the same as that shown in Fig. 8. Note that in the fifth modified example, similar to the third and fourth modified examples, the first communication device 10 does not need to be a jamming device. Therefore, in the fifth modified example, the first communication device 10 does not execute the series of processes shown in Fig. 10.

[0274] 23 shows a series of processes executed when the first communication device 10 transmits a stop request signal. This series of processes is executed by the processing device 11 of the first communication device 10. This series of processes is executed when the first communication device 10 acquires information on the number of communication errors that occurred during a predetermined number of data transmissions from the first communication device 10, the second communication device 20, or the management device 50.

[0275] 23, when this series of processes starts, in the process of step S161, the processing device 11 determines whether the number of communication errors in the communication device from which the information was obtained is equal to or greater than a predetermined value. This process is the same as the process of step S101 in FIG. 10.

[0276] In the process of step S161, if the processing device 11 determines that the number of communication errors is not equal to or greater than the predetermined value (step S161: NO), the processing device 11 ends this series of processes. In the process of step S161, if the processing device 11 determines that the number of communication errors is equal to or greater than the predetermined value (step S161: YES), the processing device 11 proceeds to the process of step S162. In the process of step S162, the processing device 21 transmits a stop request signal. At this time, the processing device 11 transmits the stop request signal according to the first communication method. This process corresponds to the process executed by the first communication device 10 in the upper part of FIG. 22.

[0277] 24 shows the flow of a series of processes when the management device 50 stops transmitting a start signal. This series of processes is executed by the processing device 51 of the management device 50. This series of processes is executed when the management device 50 receives a stop request signal.

[0278] 24, when this series of processes is started, in the process of step S171, the processing device 51 grasps the situation of the vehicle 101. This process is similar to the process executed by the processing device 11 in step S102 of FIG.

[0279] In the next step S172, the processing device 51 determines whether or not the plurality of communication devices in the communication network system 100 of the fifth modified example can switch to the second communication method. This process is similar to the process executed by the processing device 11 in step S103 of FIG. 10 .

[0280] In the process of step S172, if the processor 51 determines that the plurality of communication devices are not capable of switching to the second communication method (step S172: NO), the processor 51 ends this series of processes.

[0281] In the process of step S172, if the processing device 51 determines that the plurality of communication devices can switch to the second communication method (step S172: YES), the processing device 51 proceeds to the process of step S173. In the process of step S173, the processing device 51 stops transmitting the start signal 40. This process corresponds to the process executed by the management device 50 in the upper part of FIG. 22 .

[0282] The communication network system 100 is mounted on a vehicle 101. The management device 50 grasps the status of the vehicle 101. When the management device 50 receives a stop request signal, the management device 50 stops transmitting the start signal based on the grasped status of the vehicle 101.

[0283] In the communication network system 100 of the fifth modified example, the management device 50 determines whether or not to stop the transmission of the start signal 40 depending on the status of the vehicle 101. As a result, the communication network system 100 of the fifth modified example can prioritize ensuring opportunities to transmit data by not stopping the transmission of the start signal 40 depending on the status of the vehicle 101.

[0284] <Supplementary Notes> The technical ideas that can be understood from the above-described embodiments and modified examples will be described below. [Supplementary Note 1] A communication network system comprising: a plurality of communication devices; a management device configured to transmit a start signal to the plurality of communication devices; and a jamming device configured to transmit a jamming signal that jams the plurality of communication devices from sensing the start signal, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which data is transmitted in a predetermined order after the communication devices sense the start signal, the jamming device is configured to transmit the jamming signal in response to a communication error situation in the communication network system, and when a state in which the start signal is not sensed continues for a predetermined time, the plurality of communication devices are configured to switch the communication method to a second communication method in which data is transmitted when no other communication device is transmitting data, regardless of the predetermined order.

[0285] [Supplementary Note 2] The communication network system described in [Supplementary Note 1], wherein the jamming device is configured to acquire the status of the communication error in the communication network system and transmit the jamming signal based on the acquired status of the communication error.

[0286] [Appendix 3] The communication network system described in [Appendix 2] is mounted on a vehicle, and the jamming device is configured to grasp the status of the vehicle and transmit the jamming signal based on the acquired status of the communication error and the grasped status of the vehicle.

[0287] [Appendix 4] A communication network system described in [Appendix 2] or [Appendix 3], wherein the jamming device is configured to obtain, as the communication error status, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times.

[0288] [Appendix 5] A communication network system described in [Appendix 2] or [Appendix 3], wherein the jamming device is configured to obtain, as the status of the communication error, information on the number of communication errors that occur while data is transmitted a predetermined number of times in the communication network system.

[0289] [Appendix 6] A communication network system described in [Appendix 4] or [Appendix 5], wherein the jamming device is configured to transmit the jamming signal when the number of communication errors acquired is greater than or equal to a predetermined value.

[0290] [Appendix 7] A communication network system as described in [Appendix 4], in which a default value is set for each of the communication devices, and the jamming device is configured to transmit the jamming signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

[0291] [Supplementary Note 8] A communication network system as described in [Supplementary Note 1], further comprising a jamming request device configured to transmit a jamming request signal requesting the jamming device to transmit the jamming signal, wherein the jamming request device is configured to acquire the status of the communication error in the communication network system and transmit the jamming request signal based on the acquired status of the communication error, and the jamming device is configured to transmit the jamming signal when it receives the jamming request signal.

[0292] [Appendix 9] The communication network system described in [Appendix 8] is mounted on a vehicle, and the interference request device is configured to grasp the status of the vehicle and transmit the interference request signal based on the acquired status of the communication error and the grasped status of the vehicle.

[0293] [Appendix 10] The communication network system described in [Appendix 8] is mounted on a vehicle, and the jamming device is configured to grasp the status of the vehicle and, when receiving the jamming request signal, transmit the jamming signal based on the grasped status of the vehicle.

[0294] [Appendix 11] A communication network system described in any one of [Appendix 8] to [Appendix 10], wherein the interference request device is configured to acquire, as the communication error status, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times.

[0295] [Appendix 12] The interference request device is configured to acquire, as the status of the communication error, information on the number of communication errors that occurred while data was transmitted a predetermined number of times in the communication network system. A communication network system described in any one of [Appendix 8] to [Appendix 10].

[0296] [Appendix 13] A communication network system described in [Appendix 11] or [Appendix 12], wherein the interference request device is configured to transmit the interference request signal when the number of communication errors acquired is greater than or equal to a predetermined value.

[0297] [Appendix 14] A communication network system as described in [Appendix 11], in which a default value is set for each of the communication devices, and the interference request device is configured to transmit the interference request signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

[0298] [Appendix 15] A communication network system described in any one of [Appendix 3] to [Appendix 7] and [Appendix 10] to [Appendix 14], wherein the jamming device is configured not to transmit the jamming signal when the grasped status of the vehicle is that the vehicle is in autonomous driving.

[0299] [Appendix 16] The communication network system described in any one of [Appendix 3] to [Appendix 7] and [Appendix 10] to [Appendix 14], wherein the jamming device is configured not to transmit the jamming signal when the grasped status of the vehicle is that the vehicle is undergoing a fault diagnosis.

[0300] [Appendix 17] A communication network system described in any one of [Appendix 9] and [Appendix 11] to [Appendix 14], wherein the interference request device is configured not to transmit the interference request signal when the grasped vehicle status is that the vehicle is in automatic driving.

[0301] [Appendix 18] A communication network system described in any one of [Appendix 9] and [Appendix 11] to [Appendix 14], wherein the interference request device is configured not to transmit the interference request signal if the vehicle's status as determined is that the vehicle is undergoing a fault diagnosis.

[0302] [Supplementary Note 19] A jamming device applicable to a communication network system, the communication network system comprising a plurality of communication devices and a management device that transmits a start signal to the plurality of communication devices, the plurality of communication devices being configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, the plurality of communication devices being configured to switch communication methods to a second communication method in which the communication devices transmit data when other communication devices are not transmitting data, regardless of the predetermined order, if a state in which the start signal is not detected continues for a predetermined time, and the jamming device being configured to transmit a jamming signal that interferes with the communication devices detecting the start signal depending on the status of a communication error in the communication network system.

[0303] [Supplementary Note 20] The jamming device described in [Supplementary Note 19] is configured to acquire the status of the communication error in the communication network system and transmit the jamming signal based on the acquired status of the communication error.

[0304] [Supplementary Note 21] The communication network system is mounted on a vehicle and is configured to grasp the status of the vehicle and transmit the jamming signal based on the acquired status of the communication error and the grasped status of the vehicle. The jamming device described in [Supplementary Note 20].

[0305] [Appendix 22] A jamming device as described in [Appendix 20] or [Appendix 21], configured to acquire, as the status of the communication error, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times.

[0306] [Supplementary Note 23] A jamming device as described in [Supplementary Note 20] or [Supplementary Note 21], configured to acquire information on the number of communication errors that occurred while data was being transmitted a predetermined number of times in the communication network system as the status of the communication error.

[0307] [Supplementary Note 24] The jamming device according to [Supplementary Note 22] or [Supplementary Note 23], configured to transmit the jamming signal when the acquired number of communication errors is equal to or greater than a predetermined value. [Supplementary Note 25] The jamming device according to [Supplementary Note 22], wherein a predetermined value is set for each of the communication devices, and configured to transmit the jamming signal when the number of communication errors for any of the communication devices among the plurality of communication devices is equal to or greater than the predetermined value.

[0308] [Appendix 26] A jamming device described in any one of [Appendix 21] to [Appendix 25], configured not to transmit the jamming signal when the grasped vehicle status is that the vehicle is in automatic driving.

[0309] [Appendix 27] A jamming device described in any one of [Appendix 21] to [Appendix 25], configured not to transmit the jamming signal when the grasped vehicle status is that the vehicle is undergoing a fault diagnosis.

[0310] [Appendix 28] A communication network system comprising a plurality of communication devices and a management device configured to transmit a start signal to the plurality of communication devices, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, the management device is configured to stop transmitting the start signal depending on a communication error situation in the communication network system, and the plurality of communication devices are configured to switch their communication method to a second communication method in which the communication device transmits data when other of the communication devices are not transmitting data, regardless of the predetermined order, when a state in which the start signal is not detected continues for a predetermined time.

[0311] [Appendix 29] The communication network system described in [Appendix 28], wherein the management device is configured to acquire the status of the communication error in the communication network system and stop transmitting the start signal based on the acquired status of the communication error.

[0312] [Appendix 30] The communication network system described in [Appendix 29] is mounted on a vehicle, and the management device is configured to grasp the status of the vehicle and stop transmitting the start signal based on the acquired status of the communication error and the grasped status of the vehicle.

[0313] [Appendix 31] A communication network system as described in [Appendix 29] or [Appendix 30], wherein the management device is configured to obtain, as the communication error status, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times.

[0314] [Appendix 32] A communication network system as described in [Appendix 29] or [Appendix 30], wherein the management device is configured to obtain, as the status of the communication error, information on the number of communication errors that occurred while data was being transmitted a predetermined number of times in the communication network system.

[0315] [Appendix 33] A communication network system described in [Appendix 31] or [Appendix 32], wherein the management device is configured to stop sending the start signal when the number of communication errors acquired is greater than or equal to a predetermined value.

[0316] [Appendix 34] A communication network system as described in [Appendix 31], wherein a default value is set for each of the communication devices, and the management device is configured to stop sending the start signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

[0317] [Appendix 35] A communication network system as described in [Appendix 28], further comprising a stop request device configured to send a stop request signal to the management device requesting that the transmission of the start signal be stopped, the stop request device configured to acquire the status of the communication error in the communication network system and transmit the stop request signal based on the acquired status of the communication error, and the management device configured to stop transmitting the start signal when it receives the stop request signal.

[0318] [Appendix 36] The communication network system described in [Appendix 35] is mounted on a vehicle, and the stop request device is configured to grasp the status of the vehicle and transmit the stop request signal based on the acquired status of the communication error and the grasped status of the vehicle.

[0319] [Appendix 37] The communication network system described in [Appendix 35] is mounted on a vehicle, and the management device is configured to grasp the status of the vehicle and, when receiving the stop request signal, stop transmitting the start signal based on the grasped status of the vehicle.

[0320] [Appendix 38] A communication network system described in any one of [Appendix 35] to [Appendix 37], wherein the stop request device is configured to obtain, as the status of the communication error, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times.

[0321] [Appendix 39] A communication network system described in any one of [Appendix 35] to [Appendix 37], wherein the stop request device is configured to obtain, as the status of the communication error, information on the number of communication errors that occurred while data was transmitted a predetermined number of times in the communication network system.

[0322] [Appendix 40] A communication network system described in [Appendix 38] or [Appendix 39], wherein the stop request device is configured to send the stop request signal when the number of communication errors acquired is greater than or equal to a predetermined value.

[0323] [Appendix 41] A communication network system as described in [Appendix 38], in which a default value is set for each of the communication devices, and the stop request device is configured to transmit the stop request signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

[0324] [Appendix 42] The communication network system described in any one of [Appendix 30] to [Appendix 34] and [Appendix 37] to

[41] , wherein the management device is configured not to stop transmitting the start signal when the vehicle's status as determined is that the vehicle is in automatic driving.

[0325] [Appendix 43] A communication network system described in any one of [Appendix 30] to [Appendix 34] and [Appendix 37] to

[41] , wherein the management device is configured not to stop transmitting the start signal if the vehicle's status as determined is that the vehicle is undergoing a fault diagnosis.

[0326] [Appendix 44] The communication network system described in any one of [Appendix 36] and [Appendix 38] to [Appendix 41], wherein the stop request device is configured not to transmit the stop request signal when the grasped vehicle status is that the vehicle is in automatic driving.

[0327] [Appendix 45] A communication network system described in any one of [Appendix 36] and [Appendix 38] to [Appendix 41], wherein the stop request device is configured not to send the stop request signal if the vehicle's status as determined is that the vehicle is undergoing a fault diagnosis.

[0328] [Appendix 46] A management device that transmits a start signal in a communication network system having a plurality of communication devices, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, and the management device is configured to switch the communication method to a second communication method in which each of the communication devices transmits data when other of the communication devices are not transmitting data, regardless of the predetermined order, if the start signal is not detected for a predetermined period of time, and the management device is configured to stop transmitting the start signal depending on the status of a communication error in the communication network system.

[0329] [Appendix 47] The management device described in [Appendix 46] is configured to acquire the status of the communication error in the communication network system and stop transmitting the start signal based on the acquired status of the communication error.

[0330] [Appendix 48] The communication network system is mounted on a vehicle and is configured to grasp the status of the vehicle and stop transmitting the start signal based on the acquired status of the communication error and the grasped status of the vehicle. [Appendix 47] The management device described in

[0331] [Appendix 49] A management device as described in [Appendix 47] or [Appendix 48], configured to acquire, as the status of the communication error, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmitted data a predetermined number of times.

[0332] [Appendix 50] A management device described in [Appendix 47] or [Appendix 48], configured to obtain information on the number of communication errors that occurred while data was being transmitted a predetermined number of times in the communication network system as the status of the communication error.

[0333] [Supplementary Note 51] The management device according to [Supplementary Note 49] or [Supplementary Note 50], configured to stop transmission of the start signal when the acquired number of communication errors is equal to or greater than a predetermined value. [Supplementary Note 52] The management device according to [Supplementary Note 49], configured to stop transmission of the start signal when a predetermined value is set for each of the communication devices and when the number of communication errors for any of the communication devices among the plurality of communication devices is equal to or greater than the predetermined value.

[0334] [Appendix 53] A management device described in any one of [Appendix 48] to [Appendix 52], configured not to stop transmitting the start signal if the grasped vehicle status indicates that the vehicle is in automatic driving.

[0335] [Appendix 54] A management device described in any one of [Appendix 48] to [Appendix 52], configured not to stop sending the start signal if the grasped vehicle status is that the vehicle is undergoing a fault diagnosis.

[0336] [Appendix 55] A communication network system described in any one of [Appendix 1] to [Appendix 18] and [Appendix 28] to [Appendix 45], wherein each of the plurality of communication devices is configured to, when switching the communication method from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, set an offset time which is the time from the time the communication method is switched to the second communication method to the time when data transmission starts, and start transmitting data when the set offset time has elapsed.

[0337] [Appendix 56] A communication network system described in any one of [Appendix 1] to [Appendix 18] and [Appendix 28] to [Appendix 45], wherein each of the plurality of communication devices is configured to, when switching the communication method from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, set an offset time, which is the time from the time the communication method is switched to the second communication method to the time when data transmission starts, so that the offset time becomes shorter the larger the amount of data to be transmitted, and start transmitting data when the set offset time has elapsed.

[0338] [Appendix 57] A communication network system described in any one of [Appendix 1] to [Appendix 18] and [Appendix 28] to [Appendix 45], wherein priorities are set in advance for the plurality of communication devices, and each of the plurality of communication devices is configured so that, when the communication method is switched from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, the offset time, which is the time from the point at which the communication method is switched to the second communication method to the start of data transmission, is set to be shorter the higher the priority, and the communication device starts transmitting data when the set offset time has elapsed.

Claims

1. A communication network system comprising: a plurality of communication devices; a management device configured to transmit a start signal to the plurality of communication devices; and a jamming device configured to transmit a jamming signal to disrupt detection of the start signal by the plurality of communication devices, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, and the jamming device is configured to transmit the jamming signal in response to a communication error situation in the communication network system, and wherein the plurality of communication devices are configured, when a state in which the start signal is not detected continues for a predetermined time, to switch communication methods to a second communication method in which the communication devices transmit data when the other communication devices are not transmitting data, regardless of the predetermined order.

2. The communication network system according to claim 1, wherein the jamming device is configured to: acquire a status of the communication error in the communication network system; and transmit the jamming signal based on the acquired status of the communication error.

3. The communication network system of claim 2, wherein the communication network system is mounted on a vehicle, and the jamming device is configured to grasp the status of the vehicle and transmit the jamming signal based on the acquired status of the communication error and the grasped status of the vehicle.

4. The communication network system of claim 2, wherein the jamming device is configured to obtain, as the communication error status, information on the number of communication errors that occurred while at least one of the plurality of communication devices transmits data a predetermined number of times.

5. The communication network system according to claim 2, wherein the jamming device is configured to obtain, as the communication error status, information on the number of communication errors that occur while data is transmitted a predetermined number of times in the communication network system.

6. The communication network system according to claim 4 or 5, wherein the jamming device is configured to transmit the jamming signal when the number of acquired communication errors is equal to or greater than a predetermined value.

7. The communication network system of claim 4, wherein a default value is set for each of the communication devices, and the jamming device is configured to transmit the jamming signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

8. The communication network system of claim 1, further comprising a jamming request device configured to transmit a jamming request signal requesting the jamming device to transmit the jamming signal, the jamming request device configured to acquire a communication error status in the communication network system and transmit the jamming request signal based on the acquired communication error status, and the jamming device configured to transmit the jamming signal when it receives the jamming request signal.

9. The communication network system according to claim 8, wherein the communication network system is mounted on a vehicle, and the interference request device is configured to grasp the status of the vehicle and transmit the interference request signal based on the acquired status of the communication error and the grasped status of the vehicle.

10. The communication network system of claim 8, wherein the communication network system is mounted on a vehicle, and the jamming device is configured to grasp the status of the vehicle and, upon receiving the jamming request signal, transmit the jamming signal based on the grasped status of the vehicle.

11. The communication network system described in claim 8, wherein the interference request device is configured to obtain, as the communication error status, information on the number of times that the communication error occurred while at least one of the plurality of communication devices transmits data a predetermined number of times.

12. The communication network system according to claim 8, wherein the interference request device is configured to obtain, as the communication error status, information on the number of times that the communication error has occurred while data is transmitted a predetermined number of times in the communication network system.

13. The communication network system according to claim 11 or 12, wherein the interference request device is configured to transmit the interference request signal when the number of acquired communication errors is equal to or greater than a predetermined value.

14. The communication network system of claim 11, wherein a default value is set for each of the communication devices, and the interference request device is configured to transmit the interference request signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

15. A communication network system according to claim 3 or claim 10, wherein the jamming device is configured not to transmit the jamming signal when the grasped vehicle status indicates that the vehicle is in autonomous driving.

16. The communication network system according to claim 3 or claim 10, wherein the jamming device is configured not to transmit the jamming signal when the grasped vehicle status is that the vehicle is undergoing a fault diagnosis.

17. The communication network system according to claim 9, wherein the interference request device is configured not to transmit the interference request signal when the grasped vehicle status indicates that the vehicle is in autonomous driving.

18. The communication network system according to claim 9, wherein the interference request device is configured not to transmit the interference request signal when the grasped vehicle status is that the vehicle is undergoing a fault diagnosis.

19. A jamming device applicable to a communication network system, the communication network system comprising a plurality of communication devices and a management device that transmits a start signal to the plurality of communication devices, the plurality of communication devices being configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, the plurality of communication devices being configured to switch communication methods to a second communication method in which the communication devices transmit data when the other communication devices are not transmitting data, regardless of the predetermined order, when a state in which the start signal is not detected continues for a predetermined time, and the jamming device being configured to transmit a jamming signal that interferes with the detection of the start signal by the plurality of communication devices according to a communication error situation in the communication network system.

20. A communication network system comprising: a plurality of communication devices; and a management device configured to transmit a start signal to the plurality of communication devices, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal; the management device is configured to stop transmitting the start signal depending on a communication error situation in the communication network system; and wherein the plurality of communication devices are configured, when a state in which the start signal is not detected continues for a predetermined time, to switch the communication method to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order.

21. The communication network system according to claim 20, wherein the management device is configured to: acquire a status of the communication error in the communication network system; and stop transmitting the start signal based on the acquired status of the communication error.

22. The communication network system of claim 21, wherein the communication network system is mounted on a vehicle, and the management device is configured to grasp the status of the vehicle and stop transmitting the start signal based on the acquired status of the communication error and the grasped status of the vehicle.

23. The communication network system according to claim 21, wherein the management device is configured to obtain, as the communication error status, information on the number of times that the communication errors occurred while at least one of the plurality of communication devices transmits data a predetermined number of times.

24. The communication network system according to claim 21, wherein the management device is configured to obtain, as the communication error status, information on the number of times that the communication error occurred while data was being transmitted a predetermined number of times in the communication network system.

25. The communication network system according to claim 23 or 24, wherein the management device is configured to stop transmitting the start signal when the acquired number of communication errors is equal to or greater than a preset value.

26. The communication network system of claim 23, wherein a default value is set for each of the communication devices, and the management device is configured to stop transmitting the start signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

27. The communication network system of claim 20, further comprising a stop request device configured to transmit a stop request signal to the management device to request the management device to stop transmitting the start signal, the stop request device configured to acquire a status of the communication error in the communication network system and transmit the stop request signal based on the acquired status of the communication error, and the management device configured to stop transmitting the start signal when the stop request signal is received.

28. The communication network system described in claim 27, wherein the communication network system is mounted on a vehicle, and the stop request device is configured to grasp the status of the vehicle and transmit the stop request signal based on the acquired status of the communication error and the grasped status of the vehicle.

29. The communication network system described in claim 27, wherein the communication network system is mounted on a vehicle, and the management device is configured to grasp the status of the vehicle and, when the stop request signal is received, to stop transmitting the start signal based on the grasped status of the vehicle.

30. The communication network system described in claim 27, wherein the stop request device is configured to obtain, as the communication error status, information on the number of times that the communication error occurred while at least one of the plurality of communication devices transmits data a predetermined number of times.

31. The communication network system according to claim 27, wherein the stop request device is configured to obtain, as the communication error status, information on the number of times that the communication error has occurred while data is transmitted a predetermined number of times in the communication network system.

32. The communication network system according to claim 30 or 31, wherein the stop request device is configured to transmit the stop request signal when the number of acquired communication errors is equal to or greater than a predetermined value.

33. The communication network system according to claim 30, wherein a default value is set for each of the communication devices, and the stop request device is configured to transmit the stop request signal when the number of communication errors for any of the plurality of communication devices becomes equal to or greater than the default value.

34. A communication network system as described in claim 22 or claim 29, wherein the management device is configured not to stop transmitting the start signal when the grasped status of the vehicle indicates that the vehicle is in autonomous driving.

35. The communication network system according to claim 22 or 29, wherein the management device is configured not to stop transmitting the start signal when the grasped status of the vehicle indicates that a fault diagnosis of the vehicle is being performed.

36. The communication network system according to claim 28, wherein the stop request device is configured not to transmit the stop request signal when the grasped vehicle status indicates that the vehicle is in autonomous driving.

37. The communication network system according to claim 28, wherein the stop request device is configured not to transmit the stop request signal when the grasped vehicle status indicates that a fault diagnosis of the vehicle is being performed.

38. A management device that transmits a start signal in a communication network system having a plurality of communication devices, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, and the plurality of communication devices are configured to switch communication methods to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order, when a state in which the start signal is not detected continues for a predetermined time, and the management device is configured to stop transmitting the start signal depending on the status of a communication error in the communication network system.

39. A communication network system as described in claim 1 or claim 20, wherein each of the plurality of communication devices is configured to, when switching the communication method from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, set an offset time which is the time from the time the communication method is switched to the second communication method to the time when data transmission starts, and start transmitting data when the set offset time has elapsed.

40. A communication network system as described in claim 1 or claim 20, wherein each of the plurality of communication devices is configured to, when switching the communication method from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, set an offset time, which is the time from the time the communication method is switched to the second communication method to the time when data transmission starts, so that the offset time becomes shorter the larger the amount of data to be transmitted, and start transmitting data when the set offset time has elapsed.

41. A communication network system as described in claim 1 or claim 20, wherein a priority order is set in advance for the multiple communication devices, and each of the multiple communication devices is configured to, when switching the communication method from the first communication method to the second communication method, if there is data to transmit immediately after switching to the second communication method, set an offset time, which is the time from the point at which the communication method is switched to the second communication method to the start of data transmission, so that the higher the priority, the shorter the offset time, and start transmitting data when the set offset time has elapsed.

42. A vehicle comprising the communication network system according to claim 1.

43. A vehicle comprising the communication network system according to claim 20.

44. A program executed by a jamming device in a communication network system, the communication network system comprising a plurality of communication devices and a management device configured to transmit a start signal, the plurality of communication devices configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, the plurality of communication devices configured to switch communication methods to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order, when a state in which the start signal is not detected continues for a predetermined time, the program causing the jamming device to transmit a jamming signal that jams the plurality of communication devices from detecting the start signal, based on a communication error status in the communication network system.

45. A program executed by a management device configured to transmit a start signal in a communication network system having a plurality of communication devices, wherein the plurality of communication devices are configured to communicate with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal, and the plurality of communication devices are configured to switch communication methods to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order, when a state in which the start signal is not detected continues for a predetermined time, and the program causes the management device to stop transmitting the start signal based on a communication error status in the communication network system.

46. ​​A communication method in a communication network system, comprising: a step of a management device transmitting a start signal; a step of a plurality of communication devices communicating with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal; a step of a jamming device transmitting a jamming signal based on a communication error situation in the communication network system; and a step of, when a state in which the plurality of communication devices do not detect the start signal continues for a predetermined time, switching the communication method to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order.

47. A communication method in a communication network system, comprising: a step of a management device transmitting a start signal; a step of a plurality of communication devices communicating with each other using a first communication method in which the communication devices transmit data in a predetermined order after detecting the start signal; a step of the management device stopping the transmission of the start signal based on a communication error status in the communication network system; and a step of, when a state in which the plurality of communication devices do not detect the start signal continues for a predetermined time, switching the communication method to a second communication method in which the communication device transmits data when the other communication devices are not transmitting data, regardless of the predetermined order.

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