Management device, communication network system, vehicle, communication method, and communication program

Abstract

The present invention provides a management device that can quickly initiate normal communication in a communication network system when the power supply status to the communication equipment changes. [Solution] Multiple communication devices 10 have a physical layer collision avoidance function that, after sensing a beacon signal, if they have data to transmit, start transmitting data within a time limit when it is their turn. When the power supply status to the communication devices 10 in the communication network system 40 changes, the management device 20 checks whether the communication devices 10 can communicate through first mode communication with the communication devices 10. After confirming that the powered communication devices 10 can communicate, the management device 20 switches the communication settings between the communication devices 10 and itself from a first setting for first mode communication to a second setting for second mode communication, which has a longer time limit than first mode communication.

Description

[[Technical Field]]

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

[0002] Patent Document 1 describes a communication network system standardized in IEEE 802.3cg-2019 and compliant with the 10BASE-T1S standard. This communication network system is composed of a management device and a plurality of communication devices.

[0003] In a communication network system, a communication device communicates with other communication devices using a physical layer collision avoidance function. Hereinafter, the physical layer collision avoidance function is referred to as PLCA. PLCA is an abbreviation for Physical-Layer Collision Avoidance.

[0004] In a communication network system configured by a plurality of communication devices having PLCA, after a beacon signal is transmitted from the management device, each communication device transmits data in a predetermined order. [[Prior Art Documents]] [[Patent Documents]]

[0005] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2024-100683 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0006] If the power supply status to communication devices in a communication network system changes, the already running communication devices and management devices will wait until power is supplied and the newly started communication devices become ready to communicate before commencing normal communication according to PLCA. It is desirable that the time between the change in the power supply status to the communication devices and the commencement of normal communication in the communication network system be as short as possible. [Means for solving the problem]

[0007] The management device that solves the above problem is a management device in a communication network system. The communication network system has a physical layer collision avoidance function that, after sensing a beacon signal, if there is data to transmit, starts transmitting data within a time limit when it is its turn, and comprises multiple communication devices that become able to communicate when power is supplied. The communication network system comprises a management device that transmits the beacon signal again after confirming that it has been the turn of all the communication devices that can communicate to transmit data after transmitting the beacon signal. This management device comprises a processing circuit and a storage device. When the power supply status to the communication devices in the communication network system changes, the processing circuit checks whether the communication devices are able to communicate through a first mode of communication with the communication devices. After the processing circuit confirms that the communication devices that are supplied with power in the communication network system are able to communicate, it switches the communication settings between the communication devices and itself from a first setting for the first mode of communication to a second setting for performing a second mode of communication with a longer time limit than the first mode of communication. After the processing circuit switches the communication setting to the second setting, it performs communication with the communication device according to the second mode.

[0008] A communication network system that solves the above problems comprises a plurality of communication devices and a management device. Each communication device has a physical layer collision avoidance function that, after sensing a beacon signal, if it has data to transmit, starts transmitting data within a time limit when it is its turn, and becomes capable of communication when power is supplied. After transmitting the beacon signal, the management device transmits the beacon signal again when it has confirmed that it is the turn of all the communication devices that can communicate to transmit data. When the power supply status to the communication devices in the communication network system changes, the management device checks whether the communication devices are capable of communication through first-mode communication with the communication devices. After confirming that the communication devices that are powered in the communication network system are capable of communication, the management device switches the communication settings of the communication devices and the management device from a first setting for first-mode communication to a second setting for second-mode communication, which has a longer time limit than first-mode communication. The management device and the communication devices perform second-mode communication after the communication settings have been switched to the second setting.

[0009] A vehicle that solves the above problems is equipped with a communication network system. The communication network system comprises a plurality of communication devices and a management device. Each communication device has a physical layer collision avoidance function that, after sensing a beacon signal, if it has data to transmit, starts transmitting data within a time limit when it is its turn, and becomes able to communicate when power is supplied. After transmitting the beacon signal, the management device transmits the beacon signal again when it has confirmed that it has been the turn of all the communication devices that can communicate to transmit data. When the power supply status to the communication devices in the communication network system changes, the management device checks whether the communication devices can communicate through a first mode of communication with the communication devices. After confirming that the communication devices that are supplied with power in the communication network system can communicate, the management device switches the communication settings between the communication devices and the management device from a first setting for the first mode of communication to a second setting for performing a second mode of communication with a longer time limit than the first mode of communication. The management device and the communication device perform the second form of communication after the communication setting has been switched to the second setting.

[0010] A communication method that solves the above problems is a communication method in a communication network system. The communication network system comprises multiple communication devices that have a physical layer collision avoidance function that, after sensing a beacon signal, if there is data to transmit, start transmitting data within a time limit when it is their turn, and which become able to communicate when power is supplied. The communication network system comprises a management device that transmits the beacon signal again after confirming that it has been the turn of all the communication devices that are able to communicate, following the transmission of the beacon signal. This communication method includes a step in which, when the power supply status to the communication devices in the communication network system changes, the management device confirms whether the communication devices are able to communicate through a first mode of communication with the communication devices. This communication method includes a step in which, after confirming that the communication devices that are supplied with power in the communication network system are able to communicate, the management device switches the communication settings between the communication devices and the management device from a first setting for the first mode of communication to a second setting for performing a second mode of communication with a longer time limit than the first mode of communication. This communication method includes the step of the communication device and the management device performing the second form of communication after the communication setting has been switched to the second setting.

[0011] The communication program that solves the above problem is a communication program executed by the processing circuit of a management device in a communication network system. The communication network system has a physical layer collision avoidance function that, when it senses a beacon signal and has data to transmit, starts transmitting data within a time limit when it is its turn, and comprises multiple communication devices that become able to communicate when power is supplied. The communication network system comprises the management device that transmits the beacon signal again after confirming that it has been the turn of all the communication devices that are able to communicate, following the transmission of the beacon signal. When the power supply status to the communication devices in the communication network system changes, this communication program causes the processing circuit to check whether the communication devices are able to communicate through a first mode of communication with the communication devices. After confirming that the communication devices that are supplied with power in the communication network system are able to communicate, this communication program causes the processing circuit to switch the communication settings between the communication devices and the management device from a first setting for the first mode of communication to a second setting for performing a second mode of communication with a longer time limit than the first mode of communication. This communication program causes the processing circuit to perform communication with the communication device in the second manner after switching the communication setting to the second setting. [Effects of the Invention]

[0012] The above-mentioned management device, communication network system, vehicle, communication method, and communication program enable the communication network system to quickly initiate normal communication when the power supply status to the communication device changes within the communication network system. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a vehicle equipped with a communication network system according to one embodiment. [Figure 2]Figure 2 shows the mode in which data is transmitted according to the physical layer collision avoidance function. [Figure 3] Figure 3 is a sequence diagram showing the processing behavior of the communication network system when the vehicle's power state is switched. [Figure 4] Figures 4(a) to 4(d) show the progression of communication content in the first mode of communication. [Figure 5] Figure 5 shows the content of the communication when a transition acknowledgment frame is transmitted in the communication of the first embodiment. [Figure 6] Figure 6 shows the communication in the second embodiment. [Figure 7] Figure 7 is a flowchart showing the sequence of processes executed by the management device when the vehicle's power state changes. [Figure 8] Figure 8 shows the content of the communication in the first embodiment in the first modification example. [Figure 9] Figure 9 shows the content of the communication in the first embodiment in the second modified example. [Modes for carrying out the invention]

[0014] An embodiment of the communication network system will be described below with reference to Figures 1 to 7. <Composition of 50 vehicles> As shown in Figure 1, the vehicle 50 is equipped with a communication network system 40. The communication network system 40 conforms to the 10BASE-T1S standard, which is standardized in IEEE 802.3cg-2019.

[0015] The communication network system 40 comprises a plurality of communication devices 10. The communication network system 40 includes a first device 11, a second device 12, a third device 13, a fourth device 14, and a fifth device 15 as communication devices 10. Each communication device 10 is an electronic control unit in the vehicle 50.

[0016] Each communication device 10 in the communication network system 40 comprises a processing circuit 16 and a storage device 17. The storage device 17 stores a program. The processing circuit 16 executes various types of processing by executing the program stored in the storage device 17. The processing circuit 16 includes a processor.

[0017] As shown in FIG. 1, the communication network system 40 comprises a management device 20. The management device 20 is an electronic control device in a vehicle 50. The management device 20 comprises a processing circuit 21 and a storage device 22. The storage device 22 stores a program. The processing circuit 21 executes various types of processing by executing the program stored in the storage device 22. The processing circuit 21 includes a processor.

[0018] The storage device 22 provided in the management device 20 stores a communication program PC. The communication program PC causes the processing circuit 21 to execute processing related to communication with the communication device 10 in the communication network system 40.

[0019] In FIG. 1, the communication line 34 is indicated by a two-dot chain line. As shown in FIG. 1, the communication line 34 serially connects the management device 20 and each of the communication devices 10 from the first device 11 to the fifth device 15. In the communication network system 40, each communication device 10 and the management device 20 are communicatively connected to each other via the communication line 34.

[0020] Note that even if one of the devices connected to the communication line 34 is not in a communicable state, data that has reached the device in the communication network system 40 can pass through the device. For example, when the first device 11 is not in a communicable state, data transmitted by the management device 20 via the communication line 34 can pass through the first device 11 and reach the communication devices 10 from the second device 12 onwards.

[0021] Communication device 10 realizes specific functions in vehicle 50 by communicating with other communication devices 10. Management device 20 transmits a beacon signal BS. The beacon signal BS is a signal that serves as a guide for the timing of when communication device 10 transmits data to other communication devices 10. Management device 20 and each communication device 10 realize the communication method shown below by communicating with each other.

[0022] In addition to transmitting the beacon signal BS, the management device 20 also functions as a communication device 10. In other words, the management device 20 communicates with the communication device 10 in the communication network system 40 to realize specific functions in the vehicle 50. At this time, the management device 20 transmits data while timing its transmission based on the beacon signal BS, similar to the communication device 10.

[0023] <Power status of vehicle 50> Vehicle 50 has multiple power states. A power state is a classification of the vehicle 50 based on the number and type of equipment to which power is supplied. When the power state changes, the power supply status to the communication device 10 in the communication network system 40 changes.

[0024] In the communication network system 40, the management device 20 and the communication device 10 are connected to a power line 30. The power line 30 is connected to a power source and supplies power to the management device 20 and the communication device 10.

[0025] The communication device 10 and the management device 20 become able to communicate when power is supplied. In other words, the number of devices that can communicate in the communication network system 40 differs depending on the power state of the vehicle 50. The vehicle 50 has three power states: battery power state, accessory power state, and ignition power state.

[0026] The communication network system 40 includes a first power line 31, a second power line 32, and a third power line 33 as power lines 30. The communication network system 40 switches the power state of the vehicle 50 by switching the power lines 30 that supply power, depending on the power state of the vehicle 50.

[0027] The first power line 31 is a power line 30 that supplies power to the vehicle 50 when it is in a battery-powered state. The battery-powered state is the power state when the system switch of the vehicle 50 is in the OFF state. In the battery-powered state, power is supplied to, for example, the clock installed in the vehicle 50. As shown in Figure 1, the first power line 31 is connected to the management device 20, the first device 11, and the second device 12. In other words, when the vehicle 50 is in a battery-powered state, the management device 20, the first device 11, and the second device 12 can communicate with each other.

[0028] The second power line 32 is a power line 30 that supplies power when the vehicle 50 is in the accessory power state. The accessory power state is the power state when the system switch of the vehicle 50 is in the ACC state. In the accessory power state, in addition to the clock mentioned above, power is supplied to the car multimedia device, car navigation device, etc., that the vehicle 50 is equipped with. As shown in Figure 1, the second power line 32 is connected to the management device 20, the first device 11, the second device 12, and the third device 13. In other words, when the vehicle 50 is in the accessory power state, the management device 20, the first device 11, the second device 12, and the third device 13 can communicate with each other.

[0029] The third power line 33 is a power line 30 that supplies power when the vehicle 50 is in the ignition power state. The ignition power state is the power state when the system switch of the vehicle 50 is in the ON state. In the ignition power state, in addition to the clock and car multimedia device mentioned above, power is supplied to the engine control device, the electric pump for the coolant, and other devices equipped in the vehicle 50. As shown in Figure 1, the third power line 33 is connected to the management device 20, the first device 11, the second device 12, the third device 13, the fourth device 14, and the fifth device 15. In other words, when the vehicle 50 is in the ignition power state, the management device 20, the first device 11, the second device 12, the third device 13, the fourth device 14, and the fifth device 15 can communicate with each other.

[0030] <Overview of Physical Layer Collision Avoidance Function> In the communication network system 40, the communication device 10 and the management device 20 have a physical layer collision avoidance function. Hereinafter, the physical layer collision avoidance function will be referred to as PLCA. PLCA is an abbreviation for Physical-Layer Collision Avoidance.

[0031] The following section will explain the overview of PLCA with reference to Figure 2. Figure 2 shows how devices with multiple PLCAs communicate according to the PLCA. Communication in accordance with PLCA takes place in a network system comprising devices with multiple PLCAs and devices that transmit beacon signals BS. Hereinafter, devices with PLCAs and devices that transmit beacon signals BS will be collectively referred to as devices in the network system.

[0032] Devices equipped with PLCA transmit data using the beacon signal BS as a guide when communicating. Each PLCA-equipped device has a predetermined sequence in which it transmits data after the beacon signal BS is transmitted. After the beacon signal BS is transmitted, each PLCA-equipped device transmits data in the predetermined order.

[0033] Figure 2 illustrates how data is transmitted during one cycle in a network system. A cycle is the period from the transmission of a beacon signal BS to the completion of data transmission by the last PLCA-equipped device in the network system, after all PLCA-equipped devices are given the opportunity to transmit data in sequence. In the example in Figure 2, three PLCA-equipped devices are in a state where they can communicate in the network system.

[0034] In Figure 2, time progresses from left to right. As shown in Figure 2, when a cycle begins, the device that transmits the beacon signal BS first transmits the beacon signal BS.

[0035] In Figure 2, in addition to the beacon signal BS, the time limit TL and the transmission data DA are shown. The transmission data DA is the data transmitted by the device with PLCA. If the transmission of the transmission data DA is not started within the time limit TL, the opportunity for that device to transmit the transmission data DA ends. The order for transmitting the transmission data DA then passes to the next device.

[0036] In Figure 2, each time limit TL is numbered. The number indicates the order in which the time limit TL started after the beacon signal BS was transmitted. Time limit TL(1) in Figure 2 is the first time limit TL to start in the cycle after the beacon signal BS was transmitted. Time limit TL(2) in Figure 2 is the second time limit TL to start in the cycle after the beacon signal BS was transmitted. Time limit TL(3) in Figure 2 is the third time limit TL to start in the cycle after the beacon signal BS was transmitted.

[0037] In one cycle, the order in which devices with PLCA are assigned corresponds to the order of the time limit TLs. When a device in a network system detects a beacon signal BS, it determines that the device assigned the first turn has been given the opportunity to transmit (TO). At the same time, the device assigned the first turn determines that it is now its turn to transmit data.

[0038] When it is determined that it is its turn, the device assigned the first turn will begin transmitting the data DA within the time limit TL(1) if it has data to transmit. As shown in Figure 2, the device assigned the first turn transmits the transmit data DA including a termination signal ES at the end of the transmit data DA. The termination signal ES indicates that the device transmitting the transmit data DA has finished transmitting it. When the device assigned the first turn transmits the termination signal ES, the transmit opportunity TO for the device assigned the first turn ends. In Figure 2, the period during which the device assigned the first turn is given a transmit opportunity TO is shown as transmit opportunity TO(1).

[0039] A device with PLCA may not have any data to transmit when it is its turn to transmit data. If the device assigned the first turn has no data to transmit, it cannot start transmitting the data DA within the time limit TL(1). In this case, the transmission opportunity TO(1) for the device assigned the first turn ends as the time limit TL(1) expires without the data DA being transmitted.

[0040] In a network system, a device determines that its transmission opportunity TO(1) has ended when it detects the termination signal ES transmitted by the device assigned the first turn. In a network system, a device determines that its transmission opportunity TO(1) has ended when the time limit TL(1) has elapsed without the device assigned the first turn transmitting the transmission data DA.

[0041] In a network system, when the transmission opportunity TO(1) of the device assigned the first turn is completed, the device assigned the second turn determines that it has been given a transmission opportunity TO. At the same time, the device assigned the second turn determines that it is now its turn to transmit data.

[0042] When it determines that it is its turn, the device assigned the second turn will begin transmitting the data DA within the time limit TL(2) if it has data to transmit. As shown in Figure 2, the device assigned the second turn transmits the data DA including the termination signal ES at the end of the data DA. When the device assigned the second turn transmits the termination signal ES, the transmission opportunity TO for that device ends. In Figure 2, the period during which the device assigned the second turn is given the transmission opportunity TO is shown as transmission opportunity TO(2).

[0043] If the device assigned the second turn has no data to send, it cannot start sending the transmission data DA within TO(2). In this case, the transmission opportunity TO(2) for the device assigned the second turn ends due to the expiration of the time limit TL(2) without the transmission data DA being sent.

[0044] In a network system, a device determines that its transmission opportunity TO(2) has ended when it detects the termination signal ES transmitted by the device assigned the second position. In a network system, a device determines that its transmission opportunity TO(2) has ended when the time limit TL(2) has elapsed without the device assigned the second position transmitting the transmission data DA.

[0045] In a network system, when the transmission opportunity TO(2) of the device assigned the second turn is completed, the device assigned the third turn determines that it has been given a transmission opportunity TO. At the same time, the device assigned the third turn determines that it is now its turn to transmit data.

[0046] When it determines that it is its turn, the device assigned the third turn will begin transmitting the data DA within the time limit TL(3) if it has data to transmit. As shown in Figure 2, the device assigned the third turn transmits the data DA including the termination signal ES at the end of the data DA. When the device assigned the third turn transmits the termination signal ES, the transmission opportunity TO for that device ends. In Figure 2, the period during which the device assigned the third turn is given the transmission opportunity TO is shown as transmission opportunity TO(3).

[0047] If the device assigned the third turn has no data to transmit, it cannot start transmitting the data DA within the time limit TL(3). In this case, the transmission opportunity TO(3) for the device assigned the third turn ends as the time limit TL(3) expires without the data DA being transmitted.

[0048] In the case of devices with PLCA, one cycle ends when the transmission opportunity TO of the device with the last assigned PLCA position finishes. In Figure 2, one cycle ends when the transmission opportunity TO(3) of the device assigned the third position finishes.

[0049] A device transmitting a beacon signal BS determines that one cycle has ended when it has detected the end of a transmission opportunity TO a number of times equal to the number of devices capable of communication. As shown in Figure 2, when a device that transmits a beacon signal BS determines that one cycle has ended, it transmits the beacon signal BS again.

[0050] In this way, devices equipped with PLCA use the beacon signal BS as a guide to time their transmissions and send the data DA in a predetermined order. As a result, collisions between transmitted data DA are suppressed in network systems composed of devices equipped with PLCA.

[0051] <Communication patterns when the power state changes> When the power supply state of the communication device 10 switches from a state where no power is supplied to a state where power is supplied, it performs setup to communicate with other communication devices 10. Then, once the powered communication device 10 has completed setup, it becomes possible to communicate with other communication devices 10.

[0052] In the communication network system 40, the communication devices 10 and the management device 20 cannot perform normal communication until all communication devices 10 that are powered by the vehicle 50 are in a state where communication is possible. Normal communication refers to communication performed by the communication devices 10 to perform specific functions in the vehicle 50. In normal communication, communication is performed in accordance with PLCA, as explained in Figure 2.

[0053] Hereafter, the normal communication performed by the communication device 10 and the management device 20 will be referred to as the second type of communication. In the communication network system 40, the communication device 10 and the management device 20 can perform the second type of communication by setting the communication settings to the second setting. The communication setting is the setting that the communication device 10 and the management device 20 use to perform communication in the communication network system 40.

[0054] The communication network system 40 performs first-mode communication before second-mode communication in order to perform second-mode communication as soon as the power state of the vehicle 50 switches. Both first-mode and second-mode communication are performed according to PLCA. The first-mode and second-mode communication differ in the length of the time limit TL and the content of the data transmitted as transmission data DA.

[0055] <An example of the type of processing that is executed when the power state changes> Figure 3 shows the processing performed by the communication network system 40 after the power state of the vehicle 50 is switched. Below, a series of processes performed by the communication network system 40 when the power state of the vehicle 50 is switched will be explained with reference to Figures 3 to 6. In the following explanation, the processes performed by the processing circuit 16 will be described as processes performed by the communication device 10, and the processes performed by the processing circuit 21 will be described as processes performed by the management device 20.

[0056] Figure 3 shows an example of how the communication network system 40 processes when the vehicle 50 changes from a battery power state to an accessory power state. When the vehicle 50 is in a battery-powered state, power is supplied to the management device 20, the first device 11, and the second device 12. When the vehicle 50 switches from a battery-powered state to an accessory-powered state, the management device 20, the first device 11, and the second device 12 continue to receive power.

[0057] In Figure 3, the management device 20, the first device 11, and the second device 12 communicate in the second mode until the power state switches to the accessory power state. When the communication device 10 and the management device 20 communicate in the second mode, the communication settings are set to the second setting.

[0058] As shown in Figure 3, the control device 20 first senses a change in the power supply status. The control device 20 determines that the power status of the vehicle 50 has changed when the power line 30 supplying power switches.

[0059] The management device 20 may be able to determine the current power status from the content of its communication with the communication device 10 in the communication network system 40. The management device 20 may also determine that the power status has switched based on the content of its communication with other communication devices 10.

[0060] When the management device 20 detects that the power state has changed, it applies the first setting as the communication setting. When the vehicle 50 switches from a battery power state to an accessory power state, the third device 13 switches from a state where no power is supplied to a state where power is supplied. In Figure 3, the third device 13 is supplied with power.

[0061] The third device 13, now powered, begins setup. <Communication in the first embodiment in Figure 3> When the management device 20 applies the first setting and becomes capable of performing the first mode of communication, the communication network system 40 starts the first mode of communication.

[0062] Figures 4 and 5 show an example of the progression of communication content after the start of communication in the first embodiment. In Figures 4 and 5, time progresses from left to right. Figures 4 and 5 show the beacon signal BS, the time limit TL, and the transmission opportunity TO, similar to Figure 2. In Figures 4 and 5, the time limit TLs are numbered, similar to Figure 2. The numbers indicate the order in which the numbered time limit TLs began after the beacon signal BS was transmitted. In Figures 4 and 5, the rectangles to the right of the beacon signal BS represent the transmitted data DA. The termination signal ES is omitted in Figures 4 and 5.

[0063] As mentioned earlier, in PLCA, the order in which the transmission data DA is sent is predetermined. In the example shown in Figure 3, the control device 20 sends the transmission data DA at TO(1). In the example shown in Figure 3, the first device 11 sends the transmission data DA at TO(2). In the example shown in Figure 3, the second device 12 sends the transmission data DA at TO(3). In the example shown in Figure 3, the third device 13 sends the transmission data DA at TO(4).

[0064] Figure 4(a) shows the content of the communication when the management device 20 starts transmitting a startup confirmation frame WCF and communication in the first mode begins. As shown in Figure 4(a), after transmitting a beacon signal BS, the management device 20 transmits a startup confirmation frame WCF as transmission data DA at TO(1). The startup confirmation frame WCF is a message that confirms whether or not the communication device 10 is ready to communicate. As shown in Figure 4(a), at this stage, the communication device 10 has not transmitted any transmission data DA.

[0065] As shown in Figure 3, after communication in the first mode is initiated, the first device 11, upon receiving the startup confirmation frame WCF, applies the first setting as the communication setting. In other words, the first device 11 switches the communication setting to be applied from the second setting to the first setting.

[0066] As shown in Figure 3, after communication in the first mode is initiated, the second device 12, upon receiving the startup confirmation frame WCF, applies the first setting as the communication setting. In other words, the second device 12 switches the communication setting to be applied from the second setting to the first setting.

[0067] Thus, when the power state of the vehicle 50 is switched, the management device 20 transmits a startup confirmation frame WCF through the first mode of communication. The communication device 10, which continues to receive power before and after the switch, switches its communication setting from the second setting to the first setting when it receives the startup confirmation frame WCF.

[0068] In the communication network system 40, a communication device 10 that continues to receive power before and after the switchover transmits a startup response frame WRF when it becomes possible to communicate in the first mode after switching the communication setting to the first setting. The startup response frame WRF is a message indicating that it has become ready to communicate. When the management device 20 receives the startup response frame WRF, it determines that the communication device 10 that transmitted the startup response frame WRF is ready to communicate.

[0069] The management device 20 repeatedly transmits a startup confirmation frame WCF until it receives a startup response frame WRF from all communication devices 10 that are powered in the accessory power state. Each time a communication device 10 receives a startup confirmation frame WCF while it is able to communicate, it transmits a startup response frame WRF.

[0070] Figure 4(b) shows the communication content when the first device 11 transmits the startup response frame WRF. As shown in Figure 4(b), after the management device 20 transmits the beacon signal BS, it transmits the startup confirmation frame WCF as the transmission data DA at TO(1). As shown in Figure 4(b), the first device 11 transmits the startup response frame WRF as the transmission data DA at TO(2). As shown in Figure 4(b), at this stage, the second device 12 and the third device 13 have not transmitted the transmission data DA.

[0071] Figure 4(c) shows the communication content when the second device 12, in addition to the first device 11, transmits a startup response frame WRF. As shown in Figure 4(c), the management device 20 transmits a beacon signal BS and then transmits a startup confirmation frame WCF as transmission data DA at TO(1). As shown in Figure 4(c), the first device 11 transmits a startup response frame WRF as transmission data DA at TO(2). As shown in Figure 4(c), the second device 12 transmits a startup response frame WRF as transmission data DA at TO(3). As shown in Figure 4(c), at this stage, the third device 13 has not transmitted any transmission data DA.

[0072] When the power supply state is switched, the communication device 10, which is now powered, applies the first setting as the communication setting during setup. Figure 4(d) shows the communication content when the third device 13 transmits the startup response frame WRF. As shown in Figure 4(d), the management device 20 transmits a beacon signal BS and then transmits a startup confirmation frame WCF as the transmission data DA at TO(1). As shown in Figure 4(d), the first device 11 transmits a startup response frame WRF as the transmission data DA at TO(2). As shown in Figure 4(d), the second device 12 transmits a startup response frame WRF as the transmission data DA at TO(3). As shown in Figure 4(d), the third device 13 transmits a startup response frame WRF as the transmission data DA at TO(4).

[0073] Thus, in the communication network system 40, when power is supplied to the communication device 10 due to a power state switch, it transmits a startup response frame WRF when the setup is complete.

[0074] As shown in Figure 4(d), at this stage, all communication devices 10 that are powered in the accessory power state have transmitted a startup response frame WRF. In Figure 3, the management device 20 terminates the transmission of the startup confirmation frame WCF when it receives startup response frames WRF from all communication devices 10 that are powered in the accessory power state. Then, the management device 20 transmits a transition confirmation frame TCF. In other words, the management device 20 transmits a transition confirmation frame TCF when it determines that all communication devices 10 that are powered in the power state after the switchover are able to communicate. The transition confirmation frame TCF indicates that the communication mode in the communication network system 40 is switching from the first mode to the second mode. After transmitting the transition confirmation frame TCF, the management device 20 switches its own communication settings from the first setting to the second setting.

[0075] Upon receiving the transition confirmation frame TCF, the communication device 10 transmits a transition acknowledgment frame TRF. In the example shown in Figure 3, the first device 11, the second device 12, and the third device 13 transmit the transition acknowledgment frame TRF. The transition acknowledgment frame TRF is a response to the transition confirmation frame TCF, indicating that the communication device 10 has received the transition confirmation frame TCF.

[0076] Figure 5 shows the content of the communication when the transition acknowledgment frame TRF is being transmitted. As shown in Figure 5, after the management device 20 transmits the beacon signal BS, it transmits the transition confirmation frame TCF as the transmission data DA at TO(1).

[0077] As shown in Figure 5, the first device 11, upon receiving the transition confirmation frame TCF, transmits the transition acknowledgment frame TRF as the transmission data DA at TO(2). As shown in Figure 5, the second device 12, upon receiving the transition confirmation frame TCF, transmits the transition acknowledgment frame TRF as the transmission data DA at TO(3). As shown in Figure 5, the third device 13, upon receiving the transition confirmation frame TCF, transmits the transition acknowledgment frame TRF as the transmission data DA at TO(4).

[0078] As shown in Figure 3, after sending the transition confirmation frame TCF, the management device 20 applies the second setting as the communication setting. In other words, after sending the transition confirmation frame TCF, the management device 20 switches the communication setting from the first setting to the second setting.

[0079] As shown in Figure 3, after the first device 11 transmits the transition acknowledgment frame TRF, it applies the second setting as the communication setting. In other words, after the first device 11 transmits the transition acknowledgment frame TRF, it switches the communication setting from the first setting to the second setting.

[0080] As shown in Figure 3, after the second device 12 transmits the transition acknowledgment frame TRF, it applies the second setting as the communication setting. In other words, after the second device 12 transmits the transition acknowledgment frame TRF, it switches the communication setting from the first setting to the second setting.

[0081] As shown in Figure 3, after the third device 13 transmits the transition acknowledgment frame TRF, it applies the second setting as the communication setting. In other words, after the third device 13 transmits the transition acknowledgment frame TRF, it switches the communication setting from the first setting to the second setting.

[0082] Thus, when the communication device 10, which is supplied with power in the power state after the switchover, receives a transition confirmation frame TCF, it transmits a transition acceptance frame TRF and switches the communication setting from the first setting to the second setting. From thereafter, the communication network system 40 begins to perform communication in the second mode.

[0083] Thus, when the power state of the vehicle 50 is switched, the management device 20 first transmits a startup confirmation frame WCF through the communication described in the first mode. A communication device 10 that continues to receive power before and after a power state switch switches its communication settings to the first setting when it receives a startup confirmation frame WCF. Subsequently, when the first mode of communication becomes possible, the communication device 10 transmits a startup response frame WRF through the first mode of communication.

[0084] The communication device 10, which is now powered by a power state switch, begins setup after power is supplied. When the setup is complete and communication is possible, the communication device 10 transmits a startup response frame WRF through the first mode of communication.

[0085] When the management device 20 receives a startup response frame WRF from all communication devices 10 that are powered in the power state after the switchover, it transmits a transition confirmation frame TCF, thereby switching the communication settings between itself and the communication devices 10 to the second setting.

[0086] Note that the communication in the first embodiment shown in Figure 4 is merely an example. In Figure 3, the first device 11 transmits the startup response frame WRF before the second device 12 and the third device 13, but depending on the order in which communication becomes possible, the second device 12 or the third device 13 may transmit the startup response frame WRF first. It is also conceivable that the first device 11, the second device 12, and the third device 13 may transmit the startup response frame WRF simultaneously.

[0087] <Communication in the second embodiment in Figure 3> As shown in Figure 3, after the communication device 10 and the management device 20 apply the second setting, the communication network system 40 starts communication in the second mode.

[0088] Figure 6 shows a second mode of communication performed in the accessory power state. In Figure 6, time progresses from left to right. As in Figure 2, Figure 6 shows the beacon signal BS, the time limit TL, and the transmission opportunity TO. In Figure 6, the time limit TLs are numbered, as in Figure 2. The numbers indicate the order in which the numbered time limit TLs started after the beacon signal BS was transmitted. In Figure 6, the rectangle shown to the right of the beacon signal BS is the transmitted data DA. In Figure 6, the termination signal ES is omitted.

[0089] In the second mode of communication, the management device 20 transmits a beacon signal BS, and then transmits a normal frame UF as the transmission data DA at TO(1). In the second mode of communication, the first device 11 transmits a normal frame UF as the transmission data DA at TO(2). In the second mode of communication, the second device 12 transmits a normal frame UF as the transmission data DA at TO(3). In the second mode of communication, the third device 13 transmits a normal frame UF as the transmission data DA at TO(4). The normal frame UF is data transmitted by the communication device 10 to realize a specific function in the vehicle 50.

[0090] The time limit TL in the second mode of communication is longer than the time limit TL in the first mode of communication. In the second mode of communication, the communication device 10 transmits various types of data as a regular frame UF in order to realize a specific function in the vehicle 50. On the other hand, in the first mode of communication, the transmission data DA transmitted by the management device 20 is the startup confirmation frame WCF and the transition confirmation frame TCF. Also, the transmission data DA transmitted by the communication device 10 is the startup response frame WRF and the transition acceptance frame TRF. In other words, in the first mode of communication, the content of the transmission data DA transmitted by the communication device 10 and the management device 20 is predetermined. Therefore, in the first mode of communication, the transmission data DA transmitted by the communication device 10 and the management device 20 will not become unexpectedly long. Furthermore, in the first mode of communication, the communication device 10 and the management device 20 can prepare the transmission data DA and start transmission within a short time limit TL.

[0091] Thus, in the first mode of communication, where the transmitted data DA is short and the time limit TL is also short, the length of one cycle tends to be shorter than in the second mode of communication. The communication network system 40 checks whether the communication device 10 can communicate through the first mode of communication, which tends to have a shorter cycle, and if it is confirmed that communication is possible, it switches the communication mode to the second mode, which is normal communication.

[0092] <Aspects of processing performed by the management device 20> Figure 7 shows a series of processes performed by the management device 20 to realize the communication shown in Figures 3 to 6. The series of processes shown in Figure 7 are performed by the communication program PC, which instructs the processing circuit 21 to execute them. The processing circuit 21 starts the series of processes shown in Figure 7 when it senses a change in the power supply status. Hereinafter, S stands for step.

[0093] As shown in Figure 7, the processing circuit 21 detects a change in the power supply status and then executes the process in S31. In the process in S31, the processing circuit 21 applies the first setting as the communication setting.

[0094] Subsequently, the processing circuit 21 executes the process in S32. In the process in S32, the processing circuit 21 confirms the number of communication devices 10 to which power is supplied in the power state after the switchover. The management device 20 stores the communication devices 10 to which power is supplied in the storage device 22 for each power supply status, in other words, for each power state of the vehicle 50. In the process in S32, the processing circuit 21 confirms the number of communication devices 10 to which power is supplied in the power state after the switchover based on the information stored in the storage device 22. The management device 20 can also confirm the power state after the switchover through the power line 30 that supplies power and through communication with the communication devices 10.

[0095] Subsequently, the processing circuit 21 executes the process in S33. In the process in S33, the processing circuit 21 transmits the beacon signal BS and the startup confirmation frame WCF. At this time, the processing circuit 21 transmits the beacon signal BS and the startup confirmation frame WCF through the communication of the first embodiment.

[0096] Subsequently, the processing circuit 21 executes the process in S34. In the process in S34, the processing circuit 21 determines whether all communication devices 10 are capable of communication. After executing the process in S33, the processing circuit 21 determines that all communication devices 10 are not capable of communication if none of the communication devices 10 transmitted a startup response frame WRF during the cycle. If the processing circuit 21 determines in the process in S34 that all communication devices 10 are not capable of communication (S34: NO), it proceeds to the process in S35.

[0097] In the processing of S35, the processing circuit 21 determines whether the number of times the startup confirmation frame WCF has been transmitted is equal to or greater than a first default value. The first default value is a threshold value used to determine whether the number of times the startup confirmation frame WCF has been transmitted is high or low.

[0098] If the processing circuit 21 determines in the S35 process that the number of transmissions of the startup confirmation frame WCF is less than the first default value (S35: NO), it will execute the processing from S32 onwards again. In other words, the processing circuit 21 will repeatedly transmit the startup response frame WRF as long as it has not finished receiving startup response frames WRF from all communication devices 10 and the number of transmissions of the startup confirmation frame WCF is less than the first default value.

[0099] If the processing circuit 21 determines in the processing of S35 that the number of times the startup confirmation frame WCF has been transmitted is equal to or greater than the first default value (S35: YES), it executes the processing of S36. In other words, if the processing circuit 21 has not yet completed receiving the startup response frames WRF from all communication devices 10, and the number of times the startup confirmation frame WCF has been transmitted is equal to or greater than the first default value, it proceeds to processing S36.

[0100] In the processing of S36, the processing circuit 21 sends a wake-up pulse to the communication device 10, which has not yet transmitted a startup response frame WRF. As shown and explained in Figure 3, the communication device 10 starts setting up on its own when power is supplied. The wake-up pulse is a signal that requests the communication device 10, which should be receiving power but has not transmitted a startup response frame WRF, to start setting up and become ready to communicate.

[0101] Subsequently, the processing circuit 21 executes the process in S37. In the process of S37, the processing circuit 21 transmits the beacon signal BS and the startup confirmation frame WCF. This process is the same as the process that the processing circuit 21 executes in S33.

[0102] Subsequently, the processing circuit 21 executes the process in S38. In the process in S38, the processing circuit 21 determines whether all communication devices 10 are capable of communication. This process is the same as the process executed by the processing circuit 21 in S34.

[0103] If the processing circuit 21 determines in the S38 process that all communication devices 10 are not capable of communication (S38: NO), it proceeds to the S39 process. In the S39 process, the processing circuit 21 determines whether the number of times the startup confirmation frame WCF has been transmitted is equal to or greater than the second default value. The second default value is a threshold for determining whether the number of times the startup confirmation frame WCF has been transmitted is high or low. The second default value is greater than the first default value.

[0104] If the processing circuit 21 determines in the S39 process that the number of times the startup confirmation frame WCF has been transmitted is less than the second default value (S39: NO), it will execute the processing from S37 onwards again. In other words, the processing circuit 21 will repeatedly transmit the startup response frame WRF as long as it has not finished receiving startup response frames WRF from all communication devices 10 and the number of times the startup confirmation frame WCF has been transmitted is less than the second default value.

[0105] If the processing circuit 21 determines in the processing of S39 that the number of times the startup confirmation frame WCF has been transmitted is equal to or greater than the second default value (S39: YES), it executes the processing of S40. In other words, if the processing circuit 21 has not yet completed receiving the startup response frames WRF from all communication devices 10, and the number of times the startup confirmation frame WCF has been transmitted is equal to or greater than the second default value, it proceeds to processing S40.

[0106] In the process of S40, the processing circuit 21 determines that the communication device 10 that does not transmit the startup response frame WRF is faulty. Subsequently, the processing circuit 21 proceeds to S41. The processing circuit 21 also proceeds to S41 if it determines in the S34 process that all communication devices 10 are capable of communication (S34: YES). Furthermore, the processing circuit 21 also proceeds to S41 if it determines in the S38 process that all communication devices 10 are capable of communication (S38: YES).

[0107] In the process of S41, the processing circuit 21 determines whether or not there has been a change in the power state of the vehicle 50 between the start of the series of processes shown in Figure 7 and the execution of the process of S41. If the processing circuit 21 determines in the processing of S41 that there has been a change in the power state of the vehicle 50 (S41: YES), it will perform the processing from S32 onwards again. In other words, if the power state of the vehicle 50 changes again between the time the power state is switched and the time the processing of S41 is executed, the processing circuit 21 will send the startup confirmation frame WCF again and check whether the communication device 10 is able to communicate.

[0108] If the processing circuit 21 determines in the processing of S41 that there has been no change in the power state of the vehicle 50 (S41: NO), it proceeds to processing S42. In the processing of S42, the processing circuit 21 transmits a transition confirmation frame TCF. At this time, the processing circuit 21 transmits the transition confirmation frame TCF through the communication of the first mode.

[0109] Subsequently, the processing circuit 21 executes the process in S43. In the process in S43, the processing circuit 21 applies the second setting as the communication setting. After that, the processing circuit 21 completes the series of processes shown in Figure 7.

[0110] From this point onward, the management device 20 will begin communicating with the communication device 10 in the second mode. <Operation of this embodiment> When the power supply status to the communication device 10 in the communication network system 40 changes, the management device 20 checks whether the powered communication device 10 is able to communicate through the first mode of communication, which has a shorter time limit TL than the second mode of communication. After confirming that the powered communication device 10 is able to communicate, the management device 20 starts the second mode of communication with the communication device 10. As described above, in the first mode of communication, the transmission data DA sent by the communication device 10 and the management device 20 will not become unexpectedly long. Furthermore, in the first mode of communication, the communication device 10 and the management device 20 can prepare the transmission data DA and start transmission within the short time limit TL.

[0111] Thus, in the first mode of communication, where the transmitted data DA is short and the time limit TL is also short, the length of time until one cycle is completed tends to be shorter than in the second mode of communication. <Effects of this embodiment> (1) When the power supply status to the communication device 10 in the communication network system 40 changes, the management device 20 can quickly initiate normal communication in the communication network system 40.

[0112] (2) The communication network system 40 is installed in the vehicle 50. The management device 20 and the multiple communication devices 10 are electronic control devices provided in the vehicle 50. The processing circuit 21 senses that the power supply status has changed when the power supply status, which is classified according to the number and type of equipment to which power is supplied, switches in the vehicle 50.

[0113] When the power state of the vehicle 50 changes, the power supply status to the communication device 10 in the communication network system 40 changes. When the power state of the vehicle 50 changes, the management device 20 senses that the power supply status to the communication device 10 in the communication network system 40 has changed and starts communication in the first mode. As a result, the management device 20 can change the mode of communication in the communication network system 40 in response to the change in the power supply status to the communication device 10 in the communication network system 40.

[0114] (3) In the communication of the first embodiment, the processing circuit 21 performs the operation of transmitting a startup confirmation frame WCF to confirm whether the communication device 10 is able to communicate or not. When the processing circuit 21 receives a startup response frame WRF from the communication device 10 that has received the startup confirmation frame WCF, it performs the operation of determining that the communication device 10 is able to communicate.

[0115] The management device 20 determines that a communication device 10 that has sent a startup response frame WRF in response to a startup confirmation frame WCF is in a state where it can communicate. This allows the management device 20 to identify which communication devices 10 have become ready to communicate after a change in the power supply status to the communication devices 10 in the communication network system 40.

[0116] (4) The storage device 22 stores information indicating which communication devices 10 are supplied with power, for each power supply status. When the power supply status changes, the processing circuit 21 checks which communication devices 10 are supplied with power in the changed power supply status based on the information stored in the storage device 22. The processing circuit 21 repeatedly sends startup confirmation frames WCF until it receives startup response frames WRF from all communication devices 10 that are supplied with power. When the processing circuit 21 receives startup response frames WRF from all communication devices 10 that are supplied with power, it switches the communication setting from the first setting to the second setting.

[0117] When the management device 20 receives a startup response frame WRF from all powered communication devices 10, it switches the communication settings between itself and the communication devices 10 from the first setting to the second setting. This allows the management device 20 to switch the communication mode in the communication network system 40 after all powered communication devices 10 have become capable of communication.

[0118] (5) When the processing circuit 21 does not receive a startup response frame WRF from the communication device 10 to which power is supplied, it performs the operation of sending a wake-up pulse, which is a signal requesting the communication device 10 to become ready for communication.

[0119] When the management device 20 does not receive a startup response frame WRF from the communication device 10, which should be receiving power, it sends a wake-up pulse to the communication device 10 to request that it become ready for communication. This allows the management device 20 to switch the communication mode in the communication network system 40 as quickly as possible when it cannot receive a startup response frame WRF.

[0120] (6) When the processing circuit 21 does not receive a startup response frame WRF from the communication device 10 to which power is supplied, it determines that the communication device 10 has failed. After determining that the communication device 10 has failed, the processing circuit 21 switches the communication settings between the communication device 10 that sent the startup response frame WRF and itself from the first setting to the second setting.

[0121] When the management device 20 fails to receive a startup response frame WRF from the communication device 10, it determines that a failure has occurred in the communication device 10 and switches the communication mode for the communication device 10 that sent the startup response frame WRF. In this way, the management device 20 can identify the communication device 10 that has failed while switching the communication mode for the communication devices 10 that are still able to communicate.

[0122] (7) When the processing circuit 21 switches the communication settings between itself and the communication device 10 from the first setting to the second setting, it transmits a transition confirmation frame TCF through the first mode of communication to indicate that it is switching from the first mode of communication to the second mode of communication.

[0123] The management device 20 switches the communication settings of the management device 20 and the communication device 10 by transmitting a transition confirmation frame (TCF). This allows the management device 20 to simultaneously switch the communication modes of the communication device 10 and the management device 20 in the communication network system 40.

[0124] (8) When the power supply status to the communication device 10 changes, the communication network system 40 checks whether the powered communication device 10 is able to communicate through a first-mode communication, which has a shorter time limit TL than the second-mode communication, which is normal communication. After the communication network system 40 confirms that the powered communication device 10 is able to communicate, the management device 20 and the communication device 10 start second-mode communication. This allows the communication network system 40 to quickly start normal communication when the power supply status to the communication device 10 changes in the communication network system 40.

[0125] (9) In the communication of the first embodiment, the management device 20 transmits a startup confirmation frame WCF to confirm whether the communication device 10 is able to communicate. When the communication device 10 receives the startup confirmation frame WCF, it transmits a startup response frame WRF indicating that it is able to communicate. When the management device 20 receives the startup response frame WRF, it determines that the communication device 10 that transmitted the startup response frame WRF is able to communicate.

[0126] The communication network system 40 determines that a communication device 10 that has sent a startup response frame WRF in response to a startup confirmation frame WCF is in a state where it can communicate. This allows the communication network system 40 to identify a communication device 10 that has become ready to communicate after a change in the power supply status to the communication device 10 in the communication network system 40.

[0127] (10) The management device 20 stores information indicating which communication devices 10 are supplied with power, for each power supply status. When the power supply status changes, the management device 20 checks which communication devices 10 are supplied with power in the changed power supply status based on the information stored in the storage device 22. The management device 20 repeatedly sends startup confirmation frames WCF until it receives startup response frames WRF from all communication devices 10 that are supplied with power. When the management device 20 receives startup response frames WRF from all communication devices 10 that are supplied with power, it switches the communication setting from the first setting to the second setting.

[0128] In the communication network system 40, when the management device 20 receives a startup response frame WRF from all powered communication devices 10, it switches the communication settings between itself and the communication devices 10 from the first setting to the second setting. This allows the communication network system 40 to switch the communication mode only after all powered communication devices 10 are in a state where communication is possible.

[0129] (11) In the communication network system 40, the communication device 10 repeatedly transmits a startup response frame WRF as long as it continues to receive a startup confirmation frame WCF. In the communication network system 40, the communication device 10 repeatedly transmits a startup response frame WRF. This allows the communication network system 40 to inform communication devices 10 that become available for communication after the initial startup response frame WRF transmission of the communication device 10 that are already in a communication-ready state.

[0130] (12) The management device 20 transmits a transition confirmation frame TCF through the first mode of communication, indicating that it is switching from the first mode of communication to the second mode of communication. After transmitting the transition confirmation frame TCF, the management device 20 switches its own communication settings from the first setting to the second setting. When the communication device 10 receives the transition confirmation frame TCF, it transmits a transition acknowledgment frame TRF, which is a response to the transition confirmation frame TCF. After transmitting the transition acknowledgment frame TRF, the communication device 10 switches its own communication settings from the first setting to the second setting.

[0131] In the communication network system 40, the management device 20 and the communication device 10 switch their communication settings in response to a transition confirmation frame (TCF). This allows the communication network system 40 to simultaneously switch the communication modes of the communication device 10 and the management device 20, which are supplied with power.

[0132] (13) The communication network system 40 is mounted on the vehicle 50. The management device 20 and the communication device 10 are electronic control devices in the vehicle 50. As a result, the communication network system 40 can quickly start normal communication when the power supply status to the electronic control devices in the vehicle 50 changes.

[0133] (14) When the power supply status to the communication device 10 changes, the vehicle 50 checks whether the powered communication device 10 is able to communicate through the first mode of communication, which has a shorter time limit TL than the second mode of communication, which is normal communication. After the vehicle 50 confirms that the powered communication device 10 is able to communicate, the management device 20 and the communication device 10 start the second mode of communication. This allows the vehicle 50 to quickly start normal communication with the communication network system 40 when the power supply status to the communication device 10 changes in the communication network system 40.

[0134] (15) The above communication method is a communication method in a communication network system 40. The communication network system 40 comprises a plurality of communication devices 10 and a management device 20. The plurality of communication devices 10 have a physical layer collision avoidance function that, after sensing a beacon signal BS, if they have data to transmit, they start transmitting data within a time limit TL when it is their turn, and become able to communicate when power is supplied. After transmitting the beacon signal BS, the management device 20 transmits the beacon signal BS again when it has confirmed that it is the turn of all communicationable communication devices 10 to transmit data. The above communication method includes a step in which, when the power supply status to the communication devices 10 in the communication network system 40 changes, the management device 20 confirms whether the communication devices 10 are able to communicate through communication in the first mode with the communication devices 10. As explained with reference to Figure 3, the above communication method includes the step of confirming that the communication device 10, which is powered in the communication network system 40, is capable of communication, and then the management device 20 switches the communication settings between the communication device 10 and the management device 20 from a first setting for communication of the first mode to a second setting for communication of the second mode, which has a longer time limit TL than communication of the first mode. As explained with reference to Figure 3, the above communication method includes the step of the communication device 10 and the management device 20 performing communication of the second mode after the communication settings have been switched to the second setting.

[0135] The communication method, when the power supply status to the communication device 10 in the communication network system 40 changes, checks whether the powered communication device 10 is able to communicate through a first mode of communication, which has a shorter time limit TL than the second mode of communication, which is normal communication. Then, in the communication method, after the management device 20 confirms that the powered communication device 10 is able to communicate, the management device 20 and the communication device 10 start the second mode of communication, which is normal communication. As a result, the communication method allows the communication network system 40 to quickly start normal communication when the power supply status to the communication device 10 in the communication network system 40 changes.

[0136] (16) When the power supply status to the communication device 10 in the communication network system 40 changes, the communication program PC checks whether the powered communication device 10 is able to communicate through a first-mode communication, which has a shorter time limit TL than the second-mode communication, which is normal communication. After confirming that the powered communication device 10 is able to communicate, the communication program PC starts second-mode communication with the communication device 10. This allows the communication program PC to quickly start normal communication with the communication network system 40 when the power supply status to the communication device 10 in the communication network system 40 changes.

[0137] In the above embodiment, the communication program PC is stored in the storage device 22. The communication program PC may also be provided already recorded on a recording medium. Examples of recording media on which the communication program PC is recorded include USB memory, SSD, SD card, CD-ROM, optical disc, etc.

[0138] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0139] The communication network system 40 does not necessarily have to be installed in the vehicle 50. The management device 20 and the communication device 10 do not necessarily have to be electronic control devices installed in the vehicle 50. The management device 20 does not need to confirm which communication device 10 is powered under the changed power supply status based on the information stored in the storage device 22 when the power supply status changes. For example, the management device 20 may confirm which communication device 10 is powered under the changed power supply status through communication with the communication device 10.

[0140] The control device 20 does not need to send a wake-up pulse. The management device 20 does not need to determine that the communication device 10 has failed if it does not receive a startup response frame WRF from the communication device 10, which is supplied with power.

[0141] In Figure 3, the communication device 10, which continues to receive power before and after the power state switch, switches its communication setting from the second setting to the first setting when it receives a startup confirmation frame WCF from the management device 20. The communication device 10, which continues to receive power before and after the power state switch, may also sense the change in power supply status itself and switch its communication setting from the second setting to the first setting.

[0142] • The management device 20 transmits a startup confirmation frame WCF in addition to the beacon signal BS during communication in the first embodiment. The management device 20 does not need to transmit the beacon signal BS and the startup confirmation frame WCF separately by including information indicating the startup confirmation frame WCF in the beacon signal BS.

[0143] The above-described communication device 10 repeatedly transmits a startup response frame WRF as long as it continues to receive a startup confirmation frame WCF in the communication of the first embodiment. The embodiments after the communication device 10 has transmitted a startup response frame WRF once are not limited to those described above.

[0144] Figure 8 shows an example of the content of a first-mode communication performed in the first modified communication network system 40. In Figure 8, the management device 20 transmits a startup information frame WDF along with a startup confirmation frame WCF as transmission data DA at TO(1). The startup information frame WDF contains information indicating that the communication device 10 is already in a state where communication is possible. When the management device 20 receives a startup response frame WRF from the communication device 10, it subsequently transmits a startup information frame WDF indicating the communication device 10 that sent the startup response frame WRF when it transmits a startup confirmation frame WCF. In this case, the communication device 10 that sent the startup response frame WRF no longer needs to send another startup response frame WRF after sending it once. Therefore, when the communication network system 40 performs the communication of the first embodiment in the manner shown in Figure 8, one cycle tends to be shorter than the communication of the first embodiment in the above embodiment.

[0145] In this case, the processing circuit 21 transmits a startup information frame WDF, which contains information about the communication device 10 that transmitted the startup response frame WRF, along with the startup confirmation frame WCF in the first mode of communication.

[0146] The management device 20 transmits information indicating the communication devices 10 that are ready to communicate, along with the startup confirmation frame WCF. This allows the management device 20 to inform communication devices 10 that become ready to communicate after the startup response frame WRF has been transmitted about the communication devices 10 that are already ready to communicate.

[0147] In this case, in the communication network system 40, the management device 20 transmits a startup information frame WDF, which contains information about the communication device 10 that transmitted the startup response frame WRF, along with the startup confirmation frame WCF in the communication according to the first embodiment.

[0148] In the communication network system 40, the management device 20 transmits information indicating the communication devices 10 that are available for communication, along with the startup confirmation frame WCF. This allows the communication network system 40 to inform communication devices 10 that become available for communication after the startup response frame WRF has been transmitted about the communication devices 10 that are already available for communication.

[0149] When the management device 20 transmits the startup information frame WDF, the communication device 10 no longer needs to repeatedly transmit the startup confirmation frame WCF. Figure 9 shows an example of the content of the first form of communication performed in the communication network system 40 of the second modified example.

[0150] Figure 9 shows the content of communication after the communication device 10, which transmits the transmission data DA at TO(2) and TO(3), has already transmitted the startup response frame WRF once. In Figure 9, the management device 20 transmits a startup information frame WDF along with a startup confirmation frame WCF as transmission data DA at TO(1). At this time, the management device 20 transmits a startup information frame WDF indicating the communication device 10 that transmits the transmission data DA at TO(2) and TO(3).

[0151] In Figure 9, the communication device 10 that transmits the transmission data DA at TO(2) and the communication device 10 that transmits the transmission data DA at TO(3) are in a relationship where they exchange the transmission data DA in the second mode of communication.

[0152] The communication device 10 that transmits the data DA at TO(2) is aware that the communication device 10 that transmits the data DA at TO(3) is able to communicate through the startup response frame WRF or startup information frame WDF. Subsequently, the communication device 10 that transmits the data DA at TO(2) switches its communication settings from the first setting to the second setting.

[0153] The communication device 10 that transmits the data DA at TO(3) is aware that the communication device 10 that transmits the data DA at TO(2) is able to communicate through the startup response frame WRF or startup information frame WDF. Subsequently, the communication device 10 that transmits the data DA at TO(3) switches the communication setting from the first setting to the second setting.

[0154] Subsequently, the communication device 10 that transmits the transmission data DA at TO(2) and the communication device 10 that transmits the transmission data DA at TO(3) perform communication in the second mode. That is, as shown in Figure 9, the communication device 10 that transmits the transmission data DA at TO(2) and the communication device 10 that transmits the transmission data DA at TO(3) transmit a normal frame UF based on the time limit TL in the second mode of communication.

[0155] In this case, when the communication device 10 determines through the first mode of communication that the other party's communication device 10 in the second mode of communication is capable of communication, it switches its own communication setting from the first setting to the second setting. The communication device 10 then initiates the second mode of communication with the other party's communication device 10.

[0156] In the communication network system 40, when a communication device 10 detects that the other party's communication device 10 is capable of communication in the second mode of communication, it initiates communication in the second mode with that party, even if the management device 20 is currently performing communication in the first mode. This allows the communication network system 40 to quickly initiate communication in the second mode for any communication device 10 capable of doing so.

[0157] [Note] The technical concepts that can be understood from the above embodiments and modified examples are described below. [Note 1] A management device in a communication network system comprising: a plurality of communication devices that, after sensing a beacon signal, if there is data to transmit, start transmitting data within a time limit when it is their turn and which become capable of communication when power is supplied; and a management device that, after transmitting the beacon signal, confirms that it is the turn of all the communication devices to transmit data, and transmits the beacon signal again, the management device comprising a processing circuit and a storage device, wherein the processing circuit performs the following actions when the power supply status to the communication devices in the communication network system changes: confirm whether the communication devices are capable of communication through a first mode of communication with the communication devices; after confirming that the communication devices that are powered in the communication network system are capable of communication, switch the communication settings between the communication devices and itself from a first setting for the first mode of communication to a second setting for performing a second mode of communication with a longer time limit than the first mode of communication; and after switching the communication settings to the second setting, perform the second mode of communication with the communication devices.

[0158] [Note 2] The communication network system is mounted on a vehicle, the management device and the plurality of communication devices are electronic control devices provided by the vehicle, and the processing circuit is the management device described in Note 1, which senses that the power supply status has changed when the power supply status, which is classified according to the number and type of equipment to which power is supplied, switches in the vehicle.

[0159] [Note 3] The management device according to Note 1 or Note 2, wherein the processing circuit performs the following actions in the communication of the first embodiment: transmit a startup confirmation frame to confirm whether or not the communication device is able to communicate; and when the communication device that has received the startup confirmation frame receives a startup response frame from the communication device indicating that it is able to communicate, determine that the communication device is able to communicate.

[0160] [Note 4] The management device according to Note 3, wherein the storage device stores information indicating which communication device is supplied with power for each power supply status, and the processing circuit, when the power supply status changes, performs the following actions: confirm which communication device is supplied with power in the changed power supply status based on the information stored in the storage device; repeatedly transmit the startup confirmation frame until it receives the startup response frame from all of the communication devices to which power is supplied; and when it receives the startup response frame from all of the communication devices to which power is supplied, it switches the communication setting from the first setting to the second setting.

[0161] [Note 5] The management device according to Note 3 or Note 4, wherein the processing circuit transmits, in the communication of the first embodiment, a startup information frame, which is information of the communication device that transmitted the startup response frame, together with the startup confirmation frame.

[0162] [Note 6] The management device according to any one of Notes 3 to 5, wherein the processing circuit transmits a wake-up pulse, which is a signal requesting the communication device to become ready for communication, when it does not receive the startup response frame from the communication device to which it is supplied with power.

[0163] [Note 7] The management device described in any one of Notes 3 to 6, wherein the processing circuit determines that the communication device has failed when it does not receive the startup response frame from the communication device to which it is supplied with power, and after determining that the communication device has failed, switches the communication settings of the communication device that sent the startup response frame and itself from the first setting to the second setting.

[0164] [Note 8] The management device according to any one of Notes 1 to 7, wherein the processing circuit transmits a transition confirmation frame indicating a switch from the first mode of communication to the second mode of communication via the first mode of communication when switching the communication settings in the communication device and itself from the first setting to the second setting.

[0165] [Note 9] A communication network system comprising: a plurality of communication devices that, after sensing a beacon signal, if there is data to transmit, start transmitting data within a time limit when it is their turn, and which become able to communicate when power is supplied; and a management device that, after transmitting the beacon signal, confirms that it is the turn of all the communication devices to transmit data, and transmits the beacon signal again, wherein when the power supply status to the communication devices in the communication network system changes, the management device confirms whether the communication devices are able to communicate through a first mode of communication with the communication devices, and after confirming that the communication devices that are supplied with power in the communication network system are able to communicate, the communication settings in the communication devices and the management device are switched from a first setting for the first mode of communication to a second setting for performing a second mode of communication with a longer time limit than the first mode of communication, and the management device and the communication devices then perform the second mode of communication after the communication settings have been switched to the second setting.

[0166] [Note 10] The communication network system according to Note 9, wherein the management device transmits a startup confirmation frame to confirm whether the communication device is able to communicate in the communication according to the first embodiment, the communication device transmits a startup response frame to indicate that it is able to communicate when it receives the startup confirmation frame, and the management device determines that the communication device that transmitted the startup response frame is able to communicate when it receives the startup response frame.

[0167] [Note 11] The communication network system according to Note 10, wherein the management device stores information indicating which communication device is supplied with power for each power supply status, and when the power supply status changes, it checks which communication device is supplied with power in the changed power supply status based on the stored information, repeatedly transmits the startup confirmation frame until it receives the startup response frame from all of the communication devices that are supplied with power, and when it receives the startup response frame from all of the communication devices that are supplied with power, it switches the communication setting from the first setting to the second setting.

[0168] [Note 12] The communication network system described in Note 10 or Note 11, wherein the communication device repeatedly transmits the startup response frame as long as it continues to receive the startup confirmation frame.

[0169] [Note 13] The communication network system according to any one of Notes 10 to 12, wherein the management device transmits a startup information frame, which is information of the communication device that transmitted the startup response frame, together with the startup confirmation frame in the communication according to the first embodiment.

[0170] [Note 14] The communication network system according to Note 10 or Note 13, wherein the communication device, through communication in the first mode, determines that the other party's communication device in communication in the second mode is capable of communication, switches its own communication setting from the first setting to the second setting, and initiates communication in the second mode with the other party's communication device.

[0171] [Note 15] The communication network system according to any one of Notes 9 to 14, wherein the management device transmits a transition confirmation frame through the first mode of communication indicating a switch from the first mode of communication to the second mode of communication, and after transmitting the transition confirmation frame, switches its own communication settings from the first setting to the second setting, and when the communication device receives the transition confirmation frame, it transmits a transition acceptance frame which is a response to the transition confirmation frame, and after transmitting the transition acceptance frame, switches its own communication settings from the first setting to the second setting.

[0172] [Appendix 16] A communication network system according to any one of Appendix 9 to 15, which is mounted on a vehicle and wherein the management device and the communication device are electronic control devices in the vehicle.

[0173] [Note 17] A vehicle equipped with a communication network system as described in any one of Notes 9 to 16. [Explanation of Symbols]

[0174] 10…Communication device 11...First device 12…Second device 13…Third device 14…Fourth device 15...Fifth device 16…Processing circuit 17...Storage device 20…Management device 21…Processing circuit 22…Storage device 30…Power line 31...1st power line 32...Second communication line 33...Third power line 34... Communication lines 40…Communication network systems 50... Vehicles BS...beacon signal TCF…Migration Confirmation Frame TL... Time limit TO… sending opportunity TRF... Transition approval frame UF...Standard frame WCF... Startup confirmation frame WDF...Startup Information Frame WRF... Startup response frame PC...communication program

Claims

1. Multiple communication devices, which have a physical layer collision avoidance function that, upon detecting a beacon signal and having data to transmit, begin transmitting data within a time limit when it is their turn, and which become capable of communication when power is supplied, The management device in a communication network system comprises: a management device that, after transmitting the beacon signal, confirms that it has been the turn of all communication devices to transmit data, and then transmits the beacon signal again; It comprises a processing circuit and a memory device. The processing circuit described above When the power supply status to the communication device in the aforementioned communication network system changes, it is confirmed whether the communication device is capable of communication through a first-mode communication with the communication device, After confirming that the communication device, which is powered in the communication network system, is capable of communication, the communication settings of the communication device and itself are switched from the first setting for communication in the first mode to the second setting for communication in the second mode, which has a longer time limit than communication in the first mode. After switching the communication settings to the second settings, the communication device and the second mode of communication are performed. Execute Management device.

2. The aforementioned communication network system is installed in the vehicle. The management device and the plurality of communication devices are electronic control devices provided by the vehicle. The processing circuit detects a change in the power supply status when the power supply state, which is classified according to the number and type of equipment to which power is supplied, switches in the vehicle. The control device according to claim 1.

3. The aforementioned processing circuit is In the communication according to the first embodiment, a startup confirmation frame is transmitted to confirm whether the communication device is able to communicate, When the communication device that received the startup confirmation frame receives a startup response frame indicating that communication is possible, it is determined that the communication device is capable of communication. Execute The control device according to claim 1.

4. The storage device stores information indicating the communication device to which power is supplied, for each power supply status. The aforementioned processing circuit is When the power supply status changes, the communication device to which power is supplied under the changed power supply status is confirmed based on the information stored in the memory device, The process involves repeatedly transmitting the startup confirmation frame until the startup response frame is received from all of the communication devices to which power is supplied, When the startup response frame is received from all of the communication devices to which power is supplied, the communication setting is switched from the first setting to the second setting. Execute The control device according to claim 3.

5. The processing circuit, in the communication according to the first embodiment, transmits a startup information frame, which is information about the communication device that transmitted the startup response frame, along with the startup confirmation frame. The control device according to claim 3.

6. The processing circuit, when it does not receive the startup response frame from the communication device to which power is supplied, executes the operation of sending a wake-up pulse, which is a signal requesting the communication device to become ready for communication. The control device according to claim 4.

7. The aforementioned processing circuit is When the startup response frame is not received from the communication device to which power is supplied, it is determined that the communication device has failed. After determining that the communication device has failed, the communication settings of the communication device that sent the startup response frame, and itself, are switched from the first setting to the second setting. Execute The control device according to claim 4.

8. The processing circuit, when switching the communication settings in the communication device and itself from the first setting to the second setting, transmits a transition confirmation frame through the first mode of communication indicating a switch from the first mode of communication to the second mode of communication. A control device according to any one of claims 1 to 7.

9. Multiple communication devices, which have a physical layer collision avoidance function that, upon detecting a beacon signal and having data to transmit, begin transmitting data within a time limit when it is their turn, and which become capable of communication when power is supplied, A communication network system comprising: a management device that, after transmitting the beacon signal, confirms that it has been the turn of all communication devices to transmit data, and then transmits the beacon signal again; The aforementioned control device is When the power supply status to the communication device in the communication network system changes, the system checks whether the communication device is able to communicate through a first-mode communication with the communication device. After confirming that the communication device, which is powered in the communication network system, is capable of communication, the communication settings in the communication device and the management device are switched from the first setting for communication in the first mode to the second setting for communication in the second mode, which has a longer time limit than communication in the first mode. The management device and the communication device shall perform the second form of communication after the communication setting has been switched to the second setting. Communication network system.

10. In the communication according to the first embodiment, the management device transmits a startup confirmation frame to confirm whether or not the communication device is able to communicate. When the communication device receives the startup confirmation frame, it transmits a startup response frame indicating that it is able to communicate. When the management device receives the startup response frame, it determines that the communication device that transmitted the startup response frame is capable of communication. The communication network system according to claim 9.

11. The aforementioned control device is Information indicating the communication device to which power is supplied is stored for each power supply status. When the power supply status changes, the communication device to which power is supplied is confirmed based on the stored information, The startup confirmation frame is repeatedly transmitted until the startup response frame is received from all of the communication devices to which power is supplied. When the startup response frame is received from all of the communication devices to which power is supplied, the communication setting is switched from the first setting to the second setting. The communication network system according to claim 10.

12. As long as the communication device continues to receive the startup confirmation frame, it will repeatedly transmit the startup response frame. The communication network system according to claim 10.

13. The management device, in the communication according to the first embodiment, transmits a startup information frame, which is information about the communication device that transmitted the startup response frame, along with the startup confirmation frame. The communication network system according to claim 10.

14. The aforementioned communication device is When, through communication in the first mode, it is determined that the other party's communication device in communication in the second mode is capable of communication, it switches its own communication settings from the first setting to the second setting. To initiate communication with the other party's communication device according to the second mode. The communication network system according to claim 10.

15. The aforementioned control device is A transition confirmation frame indicating a switch from the communication of the first mode to the communication of the second mode is transmitted through the communication of the first mode. After transmitting the transition confirmation frame, the user switches its own communication settings from the first setting to the second setting. The aforementioned communication device is When the aforementioned transition confirmation frame is received, a transition acceptance frame, which is a response to the transition confirmation frame, is sent. After sending the transition confirmation frame, it switches its own communication settings from the first setting to the second setting. A communication network system according to claim 9 or claim 10.

16. It is mounted on the vehicle, The management device and the communication device are electronic control devices in the vehicle. A communication network system according to any one of claims 9 to 14.

17. A vehicle equipped with the communication network system described in claim 9.

18. Multiple communication devices, which have a physical layer collision avoidance function that, upon detecting a beacon signal and having data to transmit, begin transmitting data within a time limit when it is their turn, and which become capable of communication when power is supplied, A communication method in a communication network system comprising: a management device that, after transmitting the beacon signal, confirms that it has been the turn of all communication devices to transmit data, and then transmits the beacon signal again; When the power supply status to the communication device in the communication network system changes, the management device confirms whether the communication device is able to communicate through a first-mode communication with the communication device. The steps include: confirming that the communication device, which is powered in the communication network system, is capable of communication; then the management device switches the communication settings between the communication device and the management device from a first setting for communication in the first mode to a second setting for communication in the second mode, which has a longer time limit than communication in the first mode; After the communication setting is switched to the second setting, the communication device and the management device perform the second form of communication. including Communication method.

19. Multiple communication devices, which have a physical layer collision avoidance function that, upon detecting a beacon signal and having data to transmit, begin transmitting data within a time limit when it is their turn, and which become capable of communication when power is supplied, A communication network system comprising: a management device that, after transmitting the beacon signal, confirms that it has been the turn of all communication devices to transmit data, and then transmits the beacon signal again, wherein the management device's processing circuit executes a communication program: When the power supply status to the communication device in the aforementioned communication network system changes, it is confirmed whether the communication device is capable of communication through a first-mode communication with the communication device, After confirming that the communication device, which is powered in the communication network system, is capable of communication, the communication settings in the communication device and the management device are switched from a first setting for communication in the first mode to a second setting for communication in the second mode, which has a longer time limit than communication in the first mode. After switching the communication settings to the second settings, the communication device and the second mode of communication are performed. The processing circuit is made to execute the above. Communication program.

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