Network system

Abstract

To diagnosis whether or not an abnormality has occurred in each terminal device even after a transition from a normal operation state to a power saving state.SOLUTION: Each of a plurality of terminal devices 12, 13, 15, 16, 18 and 19 is operable in a normal operation mode and a power saving mode. While operating in the normal operation mode, the plurality of terminal devices periodically transmit a bus management message specifying other terminal devices to operate in the normal operation mode. While operating in the power saving mode, the plurality of terminal devices periodically transmit power saving messages that do not force other terminal devices to operate in the normal operation mode. Based on the bus management messages and the power saving messages, a gateway ECU 10 diagnoses whether or not an abnormality has occurred in one or more corresponding ones of the terminal device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a network system including end devices that can operate in a normal operation mode and a power saving mode. [Background technology]

[0002] For example, Patent Document 1 discloses a network system that puts each node (ECU) to sleep on a communication bus basis or on a specific group basis. More specifically, when each node is operating normally, it periodically transmits a network management (NM) message to the communication bus. At this time, when putting each node to sleep on a specific group basis, the NM message includes information (target identifier) ​​for identifying the destination group. The NM message indicates that the node cannot transition to a sleep state (power-saving state) and requests other nodes to maintain their normal operating state.

[0003] If each node can transition to the power-saving state, it stops sending NM messages. Then, if the period during which it does not receive an NM message from another node via the communication bus exceeds a preset waiting period, it transitions to the power-saving state. When transitioning to the power-saving state, each node transmits a sleep entry message to the communication bus.

[0004] The network system of Patent Document 1 includes a monitoring node as a master that monitors whether other nodes are operating normally. When a sleep completion time, which is defined as the time required for all nodes to complete their transition to a power-saving state, has elapsed, the monitoring node checks whether a sleep entry message has been received from each node. The monitoring node then records the abnormal nodes, classifying nodes that have received a sleep entry message as normal nodes and nodes that have not received a sleep entry message as abnormal nodes.

[0005] In this way, the system of Patent Document 1 detects abnormalities not only when the node is in a normal state, but also when the node transitions to a power-saving state, based on whether or not a sleep entry message has been received. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5617875 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the case of anomaly detection based on the sleep entry message transmitted from each node, it is only possible to detect anomalies such as communication anomalies in each node when the node transitions to the power-saving state. In other words, since it is not possible to detect anomalies such as communication anomalies in each node after the transition to the power-saving state, it cannot be said that sufficient detection of anomalies in each node after the transition to the power-saving state is performed.

[0008] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a network system that is capable of diagnosing whether or not an abnormality has occurred in each terminal device even after transitioning from a normal operating state to a power-saving state. [Means for solving the problem]

[0009] In order to achieve the above object, the network system according to the present disclosure comprises: A relay device (10); a plurality of communication buses (11, 14, 17) connected to the relay device; a plurality of end devices (12, 13, 15, 16, 18, 19) connected to each of the plurality of communication buses; Each of the plurality of end devices is operable in a normal operation mode and a power saving mode; the plurality of end devices, while operating in the normal operating mode, periodically transmit bus management messages to the communication bus identifying other end devices that should operate in the normal operating mode; the plurality of end devices periodically transmit a power-saving message to the communication bus while operating in the power-saving mode, which message does not force other end devices to operate in the normal operation mode; The relay device is configured to diagnose whether or not an abnormality has occurred in the corresponding end device based on the bus management message and the power saving message.

[0010] In the network system according to the present disclosure, as described above, while a plurality of end devices are operating in the normal operation mode, they periodically transmit bus management messages to the communication bus that identify other end devices that should operate in the normal operation mode. In addition, while a plurality of end devices are operating in the power saving mode, they periodically transmit power saving messages to the communication bus that do not force the other end devices to operate in the normal operation mode. Then, the relay device diagnoses whether an abnormality has occurred in the corresponding end device based on the bus management message and the power saving message.

[0011] Therefore, according to the network system disclosed herein, even after multiple terminal devices have transitioned from a normal operating state to a power-saving state, it is possible to diagnose abnormalities in each terminal device based on the power-saving messages that are sent periodically.

[0012] The reference numbers in parentheses above merely indicate an example of a correspondence with specific configurations in the embodiments described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0013] Furthermore, the technical features of the present disclosure other than those described above will become apparent from the following description of the embodiments and the accompanying drawings. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a configuration diagram showing a configuration of a network system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a leaf device. [Figure 3] FIG. 10 is an explanatory diagram for explaining the operation of a part of the leaf node in a normal operation mode. [Figure 4] FIG. 10 is an explanatory diagram for explaining the operation of a part of the leaf node in a power saving mode. [Figure 5] 10 is a flowchart illustrating an example of processing executed in a leaf device. [Figure 6] 4 is a flowchart illustrating an example of processing executed in a gateway ECU. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a network system according to the present disclosure will be described with reference to the drawings.

[0016] FIG. 1 is a configuration diagram showing an example of the configuration of a network system 100 according to this embodiment. As shown in FIG. 1, the network system 100 includes a gateway ECU 10 as a relay device. Although FIG. 1 shows an example in which the network system 100 includes one gateway ECU 10, the network system 100 may be configured to include multiple gateway ECUs that are connected to each other so that they can communicate with each other. In this case, each of the multiple gateway ECUs may be connected to at least one terminal device via at least one communication bus.

[0017] The network system 100 can use CAN (registered trademark, the same applies hereinafter) as a communication protocol. However, the communication protocol is not limited to CAN, and the network system 100 may adopt another communication protocol such as CAN-FD. In this embodiment, the network system 100 is configured as a so-called partial network in which each terminal device is switched between a normal operation mode (wake-up state) and a power-saving mode (sleep state) for each specific terminal device or group of terminal devices. Therefore, the communication protocol adopted by the network system 100 must be compatible with partial networks. CAN or CAN-FD is an example of a communication protocol compatible with partial networks.

[0018] 1, a first communication bus 11, a second communication bus 14, and a third communication bus 17 are connected to the gateway ECU 10. Thus, while Fig. 1 shows an example in which three communication buses 11, 14, and 17 are connected to the gateway ECU 10, the number of communication buses connected to the gateway ECU 10 may be two or less, or may be four or more.

[0019] Terminal devices 12 and 13 are connected to the first communication bus 11. Terminal devices 15 and 16 are connected to the second communication bus 14. Terminal devices 18 and 19 are connected to the third communication bus 17. Each of the terminal devices 12, 13, 15, 16, 18, and 19 is, for example, an ECU (electronic control unit) for controlling a predetermined control object in a vehicle, or a sensor ECU for calculating a predetermined physical quantity based on a detection signal detected by a sensor. When it is necessary to control a control object or to calculate a predetermined physical quantity based on a detection signal from a sensor, the terminal devices 12, 13, 15, 16, 18, and 19 perform normal operation in a normal operation mode, and when it is not necessary to do so, they enter a power-saving mode. The configurations and functions of the terminal devices 12, 13, 15, 16, 18, and 19 will be described in detail later. The number of terminal devices 12, 13, 15, 16, 18, and 19 connected to each communication bus 11, 14, and 17 may be one, or may be three or more.

[0020] As a relay device, the gateway ECU 10 executes a process for relaying messages between the terminal devices 12, 13, 15, 16, 18, and 19 connected to the communication buses 11, 14, and 17. The gateway ECU 10 also executes a process for diagnosing whether or not an abnormality such as a communication abnormality has occurred in each of the terminal devices 12, 13, 15, 16, 18, and 19, based on bus management messages periodically transmitted from the terminal devices 12, 13, 15, 16, 18, and 19 in a normal operating state and power-saving messages periodically transmitted from the terminal devices in a power-saving operating state.

[0021] The gateway ECU 10 is a computer including a processor, a memory, and a storage. The processor may be, for example, a CPU, an MPU, a GPU, or a DFP that executes predetermined processing according to software. The memory is a volatile storage medium, such as a RAM, that temporarily stores the results of the processor's calculations. The storage includes a non-volatile storage medium, such as a flash memory or a ROM. The storage stores a relay processing program that the processor uses to execute message relay processing, as well as a diagnostic processing program that diagnoses whether or not an abnormality, such as a communication abnormality, has occurred in each of the terminal devices 12, 13, 15, 16, 18, and 19. Specific processing executed by the gateway ECU 10 will be described in detail later. Note that some or all of the functions of the gateway ECU 10 may be implemented by hardware, for example, using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0022] The gateway ECU 10 has a diagnostic connector 20 to which a diagnostic device (not shown) is connected. The diagnostic device diagnoses whether or not an abnormality has occurred in the gateway ECU 10 and each of the terminal devices 12, 13, 15, 16, 18, and 19. For example, the diagnostic device transmits a message to the gateway ECU 10 and each of the terminal devices 12, 13, 15, 16, 18, and 19, requesting the transmission of diagnostic data recorded when some abnormality has occurred. Then, upon receiving the diagnostic data from the gateway ECU 10 and each of the terminal devices 12, 13, 15, 16, 18, and 19, the diagnostic device diagnoses whether or not an abnormality has occurred, and if an abnormality has occurred, the type of abnormality, based on the received diagnostic data.

[0023] The gateway ECU 10 further includes an exterior communication device 21. The exterior communication device 21 can communicate wirelessly with, for example, an externally installed management server. For example, when the gateway ECU 10 diagnoses that an abnormality, such as a communication abnormality, has occurred in each of the terminal devices 12, 13, 15, 16, 18, and 19, the gateway ECU 10 can transmit the diagnosis result to the management server via the exterior communication device 21. In this case, the management server may notify the vehicle user of the action to be taken depending on the nature of the abnormality. For example, if the abnormality is serious, the user may be notified to immediately bring the vehicle to a dealer or a service shop. In addition, the management server may provide the dealer or the service shop with information regarding the nature of the abnormality. If the abnormality is minor, the management server may notify the user that the network system needs to be inspected, for example, during the next regular inspection.

[0024] 2 is a diagram showing an example of the configuration of the terminal devices 12, 13, 15, 16, 18, and 19. Since the terminal devices 12, 13, 15, 16, 18, and 19 have substantially the same configuration, the terminal device 12 will be described below as a representative example.

[0025] As shown in Fig. 2, the end device 12 includes a microcomputer 30, a transceiver 34, and a power supply IC 35. The microcomputer 30 is a known computer having a CPU, RAM, ROM, I / O, etc. The microcomputer 30 can perform various functions by, for example, using the CPU to execute various programs stored in the ROM while utilizing the temporary storage function of the RAM. Fig. 2 shows an example of the functions performed by the microcomputer 30 of the end device 12 using blocks.

[0026] The microcomputer 30 includes, as its functional units, a normal operation unit 31, a power-saving function unit 32, and a communication controller 33. The normal operation unit 31 performs normal operations of the end device 12, such as controlling a predetermined control target, calculating a predetermined physical quantity based on a detection signal detected by a sensor, and transmitting and receiving messages between end devices to obtain information necessary for controlling each control target from and to other end devices. In other words, the normal operation unit 31 is enabled in a normal operation mode in which the microcomputer 30 performs normal operations. Note that when the microcomputer 30 operates in the normal operation mode, the power-saving function unit 32 is stopped.

[0027] In addition, in the normal operation mode, the normal operation function unit 31 periodically transmits bus management messages to specific end devices or groups of end devices. These bus management messages contain identification information that specifies the end device or group of end devices to which they are sent. In other words, the bus management messages transmitted by the normal operation function unit 31 are bus management messages compatible with partial networks (PNs). Figure 3 shows how message 41, which is a message to be transmitted to another end device or a bus management message compatible with PNs, is transmitted by the normal operation function unit 31.

[0028] 3, the normal operation function unit 31 further includes a filter function 36 for selectively receiving a bus management message 40 corresponding to a PN. This filter function 36 allows only an end device or a group of end devices specified by the identification information to receive the bus management message 40. As a result, the group of end devices that has transmitted or received the bus management message 40 continues in normal operation mode based on the transmission or reception of the bus management message 40. In this way, a partial network is realized in the network system 100 according to this embodiment.

[0029] 1, for example, end device 12 and end device 15 are grouped into cluster C1, end device 13, end device 16, and end device 18 are grouped into cluster C2, and end device 19 is grouped into cluster C3. Therefore, when end device 12 transmits a bus management message corresponding to a PN including identification information specifying cluster C1 (a group of end devices) to which it belongs, the bus management message corresponding to the PN is relayed to communication bus 14 by gateway ECU 10 and received by end device 15. However, the bus management message corresponding to the PN is not received by end device 16, which belongs to cluster C2 and is connected to communication bus 14. In this way, transmission and reception of bus management messages is performed on a group-by-group basis of end devices.

[0030] The power-saving mode function unit 32 is enabled when the terminal device 12 transitions from the normal operation mode to the power-saving mode. At the same time, the normal operation function unit 31 stops its operation. When the normal operation function unit 31 of the microcomputer 30 enters a state where it is no longer necessary to perform normal operation, it stops the periodic transmission of the PN-compatible bus management message described above. Then, when the time during which the microcomputer 30 does not receive a PN-compatible bus management message addressed to itself or another terminal device in a group to which it belongs reaches a predetermined waiting time, the microcomputer 30 transitions from the normal operation mode to the power-saving mode.

[0031] As shown in FIG. 4, in the power-saving mode, the power-saving function unit 32 periodically transmits a power-saving message 42 that is not received by other end devices, including end devices in the group to which the power-saving function unit 32 belongs. The power-saving message 42 includes identification information for identifying the end device that sent the message. Therefore, each end device 12, 13, 15, 16, 18, and 19 is not forced to operate in the normal operation mode by the power-saving message 42 transmitted by other end devices, and is not prevented from operating in the power-saving mode. The power-saving message 42 transmitted by each end device 12, 13, 15, 16, 18, and 19 can only be received by the gateway ECU 10. The gateway ECU 10 can then identify the end device that transmitted the power-saving message based on the identification information contained in the power-saving message.

[0032] The power-saving function unit 32 only periodically transmits power-saving messages and does not perform any other processing, so the power consumption of the microcomputer 30 when operating in the power-saving mode can be reduced compared to the power consumption of the microcomputer 30 when operating in the normal operation mode.

[0033] The above example aims to reduce the power consumption of the microcomputer 30 when operating in the power-saving mode by limiting processing in the power-saving mode compared to processing in the normal operating mode. However, various measures can be taken in addition to or instead of the above method to reduce the power consumption of the microcomputer 30 in the power-saving mode. For example, the operating clock of the CPU when operating in the power-saving mode may be slower than the operating clock when operating in the normal operating mode. Also, the function of transmitting a power-saving message may be realized by a hardware circuit, and the power supply to the CPU and other components of the microcomputer 30 may be stopped.

[0034] The communication controller 33 temporarily stores messages received by the transceiver 34 in a receive buffer and passes them on to the normal operation function unit 31. Furthermore, the communication controller 33 temporarily stores messages generated by the normal operation function unit 31 and the power saving function unit 32 in a transmit buffer and passes them on to the transceiver 34. The communication controller 33 may be realized by a program on the microcomputer 30 or by a hardware circuit. In the communication controller 33, the receive function and transmit function may be enabled in the normal operation mode, and only the transmit function may be enabled in the power saving mode.

[0035] The transceiver 34 transmits and receives messages to and from other end devices and the transceiver of the gateway ECU via the communication bus 11. As shown in FIG. 4 , the transceiver 34 includes a filter 37 configured by a hardware circuit. When the end device 12 is operating in the power-saving mode, the filter 37 selectively receives a PN-compatible bus management message 43 directed from another end device to the end device 12, requesting that the end device 12 operate in the normal operating mode. When the filter 37 detects the reception of a PN-compatible bus management message directed to the end device 12, the filter 37 resets the microcomputer 30 via the power supply IC 35, for example, to operate the microcomputer 30 in the normal operating mode. Alternatively, if the power supply IC 35 has stopped supplying power to the CPU in the power-saving mode, the filter 37 may resume supplying power to the CPU, etc., to operate the microcomputer 30 in the normal operating mode.

[0036] In this way, each of the end devices 12, 13, 15, 16, 18, and 19 transitions from the power saving mode to the normal operating mode in response to receiving a bus management message sent from another end device. Furthermore, each of the end devices 12, 13, 15, 16, 18, and 19 can be configured to transition from the power saving mode to the normal operating mode individually in response to a signal input from a switch or a sensor.

[0037] Next, an example of the processing executed in each of the leaf nodes 12, 13, 15, 16, 18, and 19 will be described with reference to the flowchart of FIG.

[0038] In the first step S100, each of the terminal devices 12, 13, 15, 16, 18, and 19 performs normal operation. That is, each of the terminal devices 12, 13, 15, 16, 18, and 19 controls a predetermined control object, calculates a predetermined physical quantity based on a detection signal detected by a sensor, and transmits and receives messages between the terminal devices to obtain information necessary for controlling each control object from and to other terminal devices.

[0039] In the following step S110, each of the terminal devices 12, 13, 15, 16, 18, and 19 determines whether or not it is necessary to perform a normal operation. For example, each of the terminal devices 12, 13, 15, 16, 18, and 19 can determine whether or not it is necessary to control a control target based on signals from various sensors and switches. If it is determined that it is necessary to perform a normal operation, each of the terminal devices 12, 13, 15, 16, 18, and 19 proceeds to step S120. On the other hand, if it is determined that it is not necessary to perform a normal operation, each of the terminal devices 12, 13, 15, 16, 18, and 19 proceeds to step S130.

[0040] In step S120, each of the terminal devices 12, 13, 15, 16, 18, and 19 periodically transmits a bus management message corresponding to the PN. In step S130, each of the terminal devices 12, 13, 15, 16, 18, and 19 receives a bus management message corresponding to the PN from another terminal device directed to itself or the group to which it belongs. If it is determined in step S110 that normal operation is not required, step S120 is skipped, and the periodic transmission of the above-mentioned bus management message corresponding to the PN is stopped. The processing in steps S100 to S130 corresponds to the processing performed in the normal operation mode in each of the terminal devices 12, 13, 15, 16, 18, and 19.

[0041] In step S140, each of the end devices 12, 13, 15, 16, 18, and 19 determines whether it is possible to transition from the normal operation mode to the power-saving mode. Each of the end devices 12, 13, 15, 16, 18, and 19 can determine that it is possible to transition to the power-saving mode when it is not periodically transmitting a PN-compatible bus management message and the time during which it has not received a PN-compatible bus management message from another end device reaches a predetermined waiting time. If it is determined that it is possible to transition to the power-saving mode, each of the end devices 12, 13, 15, 16, 18, and 19 proceeds to step S150. On the other hand, if it is determined that it is not possible to transition to the power-saving mode, each of the end devices 12, 13, 15, 16, 18, and 19 returns to step S100.

[0042] In step S150, each of the terminal devices 12, 13, 15, 16, 18, and 19 is set not to execute the normal operation function that executes normal operation. This stops normal operation. Then, in step S160, each of the terminal devices 12, 13, 15, 16, 18, and 19 periodically transmits a power-saving message. As described above, this power-saving message is received only by the gateway ECU 10 and not by other terminal devices. Therefore, if another terminal device is in the power-saving mode, the power-saving mode will not be interrupted.

[0043] In step S170, each of the leaf nodes 12, 13, 15, 16, 18, and 19 determines whether a certain period of time has elapsed since the leaf node 12, 13, 15, 16, 18, and 19 started periodic transmission of the power-saving message. If it is determined that the certain period of time has elapsed, each of the leaf nodes 12, 13, 15, 16, 18, and 19 proceeds to step S180. On the other hand, if it is determined that the certain period of time has not yet elapsed, each of the leaf nodes 12, 13, 15, 16, 18, and 19 returns to step S160. The processing in steps S150 and S160 described above corresponds to the processing performed in the power-saving mode in each of the leaf nodes 12, 13, 15, 16, 18, and 19. In the power-saving mode, only the periodic transmission of the power-saving message is performed, and other processing (functions) are stopped.

[0044] In this embodiment, as described above, each of the leaf devices 12, 13, 15, 16, 18, and 19 does not always periodically transmit a power-save message during the power-save mode, but is configured to stop the periodic transmission of the power-save message after a certain time has elapsed since the leaf device started transmitting the power-save message. This makes it possible to further reduce the power consumption of each of the leaf devices 12, 13, 15, 16, 18, and 19 in the power-save mode.

[0045] Furthermore, since each of the terminal devices 12, 13, 15, 16, 18, and 19 periodically transmits a power saving message for a certain period of time after transitioning to the power saving mode, the gateway ECU 10 can determine, based on the power saving message, whether or not an abnormality such as a communication abnormality has occurred in each of the terminal devices 12, 13, 15, 16, 18, and 19 after transitioning to the power saving mode. Note that each of the terminal devices 12, 13, 15, 16, 18, and 19 may be configured to always periodically transmit a power saving message while in the power saving mode.

[0046] Next, an example of processing executed in the gateway ECU 10 will be described with reference to the flowchart of FIG.

[0047] In the first step S200, the gateway ECU 10 receives messages such as messages transmitted and received between the terminal devices, PN-compatible bus management messages periodically transmitted from each of the terminal devices 12, 13, 15, 16, 18, and 19 in the normal operation mode, and power-saving messages periodically transmitted from each of the terminal devices 12, 13, 15, 16, 18, and 19 in the power-saving mode. Then, in step S210, the gateway ECU 10 executes relay processing for the received messages by referring to a predefined table that indicates the communication buses 11, 14, and 17 to which the messages are to be transferred, depending on the type of message and the identification information contained in the message. However, in the power-saving mode, the power-saving messages periodically transmitted from each of the terminal devices 12, 13, 15, 16, 18, and 19 are not subject to relay processing, but are simply received by the gateway ECU 10.

[0048] In step S220, the gateway ECU 10 determines whether it periodically receives PN-compatible bus management messages from each of the end devices 12, 13, 15, 16, 18, and 19 operating in the normal operation mode. Since the gateway ECU 10 knows which group each end device belongs to, it can determine which group the end device belongs to in the normal operation mode from the received PN-compatible bus management message. If it determines that it periodically receives PN-compatible bus management messages from all end devices operating in the normal operation mode, the gateway ECU 10 proceeds to step S230. On the other hand, if it determines that it does not continuously receive PN-compatible bus management messages from any of the end devices operating in the normal operation mode, the gateway ECU 10 proceeds to step S240.

[0049] In step S230, the gateway ECU 10 determines whether or not it periodically receives power-saving messages from each of the end devices 12, 13, 15, 16, 18, and 19 operating in the power-saving mode. The gateway ECU 10 knows which group each end device belongs to, and can determine from the received power-saving message which group the end device belongs to and is operating in the power-saving mode. If it is determined that it periodically receives power-saving messages from all end devices operating in the power-saving mode, the gateway ECU 10 proceeds to step S250. On the other hand, if it is determined that it has not continuously received power-saving messages from any of the end devices operating in the power-saving mode, the gateway ECU 10 proceeds to step S240.

[0050] In step S240, the gateway ECU 10 diagnoses and records the end device that has not continuously received the PN-compatible bus management message or the power-saving message as an abnormal end device. Furthermore, in step S240, the gateway ECU 10 may notify the external management server via the external communication device 21 of the diagnosis result, including the abnormal end device. The gateway ECU 10 then returns to step S200. In this manner, in this embodiment, the gateway ECU 10 can diagnose that an abnormality has occurred in the corresponding end device based on the continuous non-reception of the PN-compatible bus management message and the power-saving message, and record the diagnosis result. In particular, according to this embodiment, the gateway ECU 10 can diagnose abnormalities in each end device based on the power-saving message that is periodically transmitted, even after the end device has transitioned from the normal operation mode to the power-saving mode.

[0051] In step S250, the gateway ECU 10 determines whether the periodic transmission of power-saving messages from all the terminal devices has stopped due to the passage of a certain time since all the terminal devices transitioned to the power-saving mode. If the gateway ECU 10 determines that the periodic transmission of power-saving messages from all the terminal devices has stopped, the gateway ECU 10 proceeds to step S260. On the other hand, if the gateway ECU 10 does not determine that the periodic transmission of power-saving messages from all the terminal devices has stopped, the gateway ECU 10 returns to step S200.

[0052] In step S260, the gateway ECU 10 stops the diagnostic processing function based on the PN-compatible bus management message and the power-saving message that are periodically transmitted. This allows the power consumption of the gateway ECU 10 to be reduced. After executing step S260, the gateway ECU 10 ends the processing shown in the flowchart of FIG. 6. In this case, the gateway ECU 10 enters a sleep state. When the gateway ECU 10 receives a bus management message from any of the end devices in the sleep state, it wakes up and starts the processing from step S200 of the flowchart of FIG. 6.

[0053] The above-described embodiments are preferred embodiments of the present disclosure, but the present disclosure is not limited to the above-described embodiments and can be implemented in various modified forms within the scope that does not deviate from the gist of the present disclosure. [Explanation of symbols]

[0054] 10: Gateway, 11: First communication bus, 12: End device, 13: End device, 14: Second communication bus, 15: End device, 16: End device, 17: Third communication bus, 18: End device, 19: End device, 20: Diagnostic connector, 21: Exterior communication device, 30: Microcomputer, 31: Normal operation function unit, 32: Power saving function unit, 33: Communication controller, 34: Transceiver, 35: Power supply IC, 100: Network system

Claims

1. A relay device (10); a plurality of communication buses (11, 14, 17) connected to the relay device; a plurality of end devices (12, 13, 15, 16, 18, 19) connected to each of the plurality of communication buses; Each of the plurality of end devices is operable in a normal operation mode and a power saving mode; the plurality of end devices, while operating in the normal operation mode, periodically transmit to the communication bus bus bus management messages that identify other end devices that should operate in the normal operation mode; the plurality of end devices periodically transmit a power saving message to the communication bus while operating in the power saving mode, the power saving message not forcing the other end devices to operate in the normal operation mode; The relay device diagnoses whether or not an abnormality has occurred in the corresponding terminal device based on the bus management message and the power saving message.

2. 2. The network system according to claim 1, wherein the end device enables only a function of periodically transmitting the power saving message while operating in the power saving mode, and disables other functions.

3. 3. The network system of claim 1, wherein a plurality of said end devices are provided with a transceiver that operates to receive said bus management message directed to a corresponding one of said end devices when operating in said power saving mode, and that operates to return said end device to said normal operating mode in response to receiving said bus management message.

4. 3. The network system according to claim 1, wherein the plurality of terminal devices terminate the periodic transmission of the power-saving message when a predetermined time has elapsed since the terminal devices started the periodic transmission of the power-saving message.

5. 5. The network system of claim 4, wherein the relay device transitions to a power saving mode, which includes stopping at least the bus management message and a diagnostic function based on the power saving message, in response to a plurality of end devices connected to each of a plurality of the communication buses connected to the relay device having terminated periodic transmission of the power saving message.

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