JP4954832B2 - In-vehicle communication system - Google Patents

Description

  The present invention relates to an in-vehicle communication system, and more particularly, to execute a network management system in the in-vehicle communication system.

  Conventionally, in vehicles, an in-vehicle communication system that connects electronic control units (ECUs) for controlling in-vehicle devices via a multiplex communication bus to construct a network and transmits / receives messages between the ECUs has been adopted. Has been.

  In recent years, a network management system has been proposed in order to ensure the safety and reliability of communication in the in-vehicle communication system. Specifically, as shown in Non-Patent Document 1, the network management system transmits and receives ring messages to and from each other, and ECUs connected to the multiplex communication bus communicate with each other to initialize the ECU, start the network, set the network, This is a system that performs processing such as detection and processing of operation states of ECUs and networks, signal transmission, error determination of each ECU, reading and setting of parameters of the ECU and the like.

In order to execute a network management system in communication between ECUs, all ECUs in the network need to have a network management function. However, at present, only some ECUs have a network management function, so an ECU having a network management function (hereinafter referred to as an NM-compatible ECU) and an ECU without a network management function (hereinafter not compatible with an NM). In many cases, the network is a mixture of both ECUs. In the case of the network, there is a problem that ring messages cannot be transmitted to each other and the network management system cannot be executed.
In addition, in order to add a network management function to an NM non-compliant ECU, software corresponding to each ECU must be developed, and there is a problem that development takes much time.

Network Management Concept and Application Programming Interface Published: July 26, 2004 Publisher: OSEK / VDX Internet (URL: http://portal.osek-vdx.org/files/pdf/specs/nm253.pdf)

  The present invention has been made in view of the above problems, and it is an object of the present invention to execute a network management system even in an in-vehicle communication system in which both an NM-compatible ECU and an NM-non-compatible ECU are mixed.

In order to solve the above-described problems, the present invention provides a network management compatible electronic control unit having a network management function and a network management non-supporting electronic control unit not having the network management function connected via a multiplex communication bus. An in-vehicle communication system,
The network management interposed incompatible electronic control unit and between the multiplex communication bus, comprising a gateway device having a network management processing circuitry to perform the network management functions of the network management incompatible electronic control unit, the gateway device provides a vehicle communication system, characterized by sending and receiving messages to the network management processing circuits is used between said network management incompatible electronic control unit via the multiplex communication bus.

According to the above configuration, a gateway device having a network management processing circuit (also referred to as a network management processing circuit unit) is interposed between an electronic control unit that does not support network management (hereinafter referred to as NM non-compliant ECU) and a multiplex communication bus. The gateway device executes a network management function for an ECU that does not support NM. That is, the NM non-compliant ECU becomes an ECU having a network management function by the gateway device. For this reason, even if it is a vehicle-mounted communication system in which both NM non- corresponding ECU and network management compatible electronic control unit (hereinafter referred to as NM compatible ECU) are mixed, the network management system can be executed.

In order to execute the network management function for the NM non-compliant ECU, the gateway device uses the network management processing circuit unit with the NM compatible ECU connected to the same multiplex communication bus instead of the NM non-compliant ECU. Send and receive ring messages.
By receiving the ring message, the gateway device can determine whether or not another ECU has an error. In addition, the gateway device receives a ring message received from another ECU so that the operation state of the other ECU is a normal state (normal operation state) that is a high power consumption state, a sleep state that is a power saving consumption state, or a normal state. It is possible to detect a sleepable state that can be shifted to a sleep state, and to perform a transition process by determining to which operation state an NM non-compliant ECU is to be shifted based on the detection result Can do.

The gateway device is connected to the network management non-compliant electronic control unit via a network management signal line and a dedicated bus or serial communication line,
A signal for executing the network management function is transmitted / received to / from the network management incompatible electronic control unit via the network management signal line.

The network management processing circuit unit of the gateway device transmits a transition signal via the network management signal line, and shifts the NM non-compliant ECU to a sleep state, a normal state, a sleep possible state, or the like. In addition, a detection signal indicating whether the current operation state is a sleep state, a normal state, a sleep possible state, or the like is received from a non-NM-compatible ECU via a network management signal line, and the other ECUs as a ring message Send to.
By connecting the gateway device and the NM non-compliant ECU using a network management signal line as a dedicated line for the network management function, the network management processing circuit unit performs network management processing for the NM non-compliant ECU at high speed. Can do.

Further, as a network management signal line, a transition signal line for transmitting a transition signal from the network management processing circuit unit to the NM incompatible ECU, and a detection in which the network management processing circuit unit receives the current operation state from the NM incompatible ECU. The signal line may be provided separately.
By providing the transition signal line and the detection signal line as separate bodies, the network management processing circuit unit can perform network management processing on the NM-incompatible ECU at higher speed.

Further, the network management processing circuit unit transmits only a signal for setting the NM incompatible ECU to the sleep state and the normal state as a transition signal through the transition signal line, and confirms that the NM incompatible ECU is in a sleep capable state. Only the signal shown may be received via the detection signal line.
By minimizing the network management function, processing of the gateway device can be reduced, and the configuration of the gateway device can be simplified.

  The gateway device relays a message transmitted and received by the electronic control unit not supporting network management with the other electronic control unit via a dedicated bus or a serial communication line.

The gateway device performs a relay process of a message (hereinafter referred to as a normal message) that is transmitted and received between an ECU that does not support NM and another ECU and controls the in-vehicle device. That is, the gateway device is connected to another ECU via a multiplex communication bus. When a normal message transmitted from another ECU is received via the multiplex communication bus, the gateway device receives the normal message from a dedicated bus or a serial bus. It is transmitted to the communication line and relayed to the NM incompatible ECU. When the gateway device receives a normal message addressed to another ECU from an NM-incompatible ECU via a dedicated bus or a serial communication line, the gateway device transmits the normal message to the multiplex communication bus.
When the NM incompatible ECU and the gateway device are connected by a dedicated bus, messages can be transmitted and received at high speed by communication such as the CAN protocol.
When the NM non-compliant ECU and the gateway device are connected by a serial communication line, a communication driver is not required for the gateway device and the NM non-compliant ECU, and the number of parts can be reduced.

It is preferable that the gateway device is connected on a one-to-one basis with the electronic control unit that does not support network management.
In a conventional gateway device, a plurality of buses are connected, and a relay table is used to determine a relay destination of a received message. On the other hand, when the NM non-compliant ECU is connected to the gateway device on a one-to-one basis, the normal message received by the gateway device via the multiplex communication bus is always transmitted to the NM non-compliant ECU. Since the received normal message is always transmitted to the multiplex communication bus, it is not necessary to determine the relay destination with reference to the routing table. This eliminates the need for a storage unit for storing the routing table and an advanced determination processing unit for determining the relay destination, simplifying the structure of the gateway device and reducing the cost.

The gateway device is
A transceiver circuitry for transmitting and receiving said message,
Contention and detection circuitry to arbitrate when the message said multiplex the communication message flowing through the bus the network management incompatible electronic control unit is transmitted to the multiplex communication bus through the gateway device has collided are transmitted simultaneously ,
A receiving buffer for storing a message received from the multiplex communication bus,
A transmission buffer for storing the message to be transmitted to the multiplex communication bus,
It has.

The message transmitted and received by the gateway device via the multiplex communication bus includes a normal message and a ring message. Since gateway device includes a conflict detection circuitry, even collide with messages other ECU transmits when sending a normal message and ring message, it is possible to perform arbitration (arbitration). The reception buffer及 beauty transmit buffer usually by using the both transmission and reception of the transceiver and the ring message in the message, it is possible to simplify the configuration of the gateway device.

The transmission buffer and the competition detecting circuit and the network management processing circuit and the receiving buffer is preferably form an integrated circuit.
An integrated circuit (Integrated Circuit) forming each part of the gateway device may be an ASIC (Application Specific Integrated Circuit) which is an integrated circuit designed and manufactured for the gateway device of the present invention. Further, an FPGA (Field Programmable Gate Array) that is an integrated circuit whose internal circuit configuration can be changed may be used.

  As described above, according to the in-vehicle communication system of the present invention, the gateway device having the network management processing circuit unit is interposed between the NM incompatible ECU and the multiplex communication bus, and the gateway device does not support NM. Since the network management function for the ECU is executed, the network management system can be executed even in an in-vehicle communication system in which both an NM-compatible ECU and an NM-non-compatible ECU are mixed.

Embodiments of the present invention will be described with reference to the drawings.
1 to 4 show a first embodiment of the present invention.
The in-vehicle communication system 10 of the present invention is configured by connecting an electronic control unit (ECU) to the multiplex communication bus 50 to form a network, and a message (for controlling an electric device or the like connected to each ECU ( (Hereinafter referred to as a normal message) is transmitted and received between the ECUs.
The ECU includes an NM compatible ECU 30 having a network management function and an NM non-compatible ECU 40 not having the network management function, and the NM compatible ECU 30 and the NM non-compatible ECU 40 are mixed in one multiplex communication bus 50. It is connected. In the present embodiment, one NM incompatible ECU 40 and two NM compatible ECUs 30 are connected to one multiplex communication bus 50. The communication protocol is CAN (Controller Area Network).

  The gateway device 20 is interposed between the NM non-compliant ECU 40 and the multiplex communication bus 50. That is, the gateway device 20 is connected to another NM-compatible ECU 30 via the multiplex communication bus 50 and is connected to the NM non-compatible ECU 40 via the dedicated bus 51 corresponding to the CAN protocol. The gateway device 20 performs network management processing for the ECU 40 that does not support NM.

As shown in FIG. 1, the gateway device 20 includes a gateway LSI 21, a power source 22, and two drivers 23A and 23B on the same substrate.
A gateway LSI 21 (Large Scale Integrated Circuit) is an integrated circuit (IC), and is configured as hardware by an ASIC designed for the gateway device 20. The gateway LSI 21 includes a network management processing circuit 24, two transmission / reception circuits 25A and 25B, a conflict detection circuit 26, a reception buffer 27, and a transmission buffer 28.

  The network management processing circuit 24 operates as a network management function of the ECU 40 that does not support NM. The network management function is to ensure the safety and reliability of communication of each ECU connected to the multiplex communication bus 50, and specifically, to transmit and receive ring messages between the ECUs 30 and 40. Thus, the operation state of each ECU is a normal state (normal operation state) that is a high power consumption state, a sleep state that is a power saving consumption state, a sleep enable state that can be shifted to the sleep state although it is a normal state, etc. This is detected and an operation state transition process is performed. Also, processing such as error determination and initialization of the ECUs 30 and 40 is performed.

The ring message is a message used by the network management processing circuit 24 among normal messages transmitted / received via the multiplex communication bus 50, and the message format of the ring message and the normal message is the same. Each message has a unique ID (identifier), and the gateway device 20 and the ECUs 30 and 40 identify whether the message is a ring message or a normal message.
The gateway device 20 transmits and receives ring messages. Since the ring message received by the gateway device 20 is processed by the network management processing circuit 24 in the gateway device 20, it is not transmitted to the ECU 40 that does not support NM. Further, the ring message is created by the network management processing circuit 24 of the gateway device 20 and transmitted to the multiplex communication bus 50, and the NM non-compliant ECU 40 does not create a ring message.

The network management processing circuit 24 is connected to the NM non-compliant ECU 40 by a network management signal line 41, and the network management signal line 41 includes a transition signal line 42 and a detection signal line 43. The NM non-compliant ECU 40 performs network management processing via the detection signal line 43 to indicate that the current operation state of the NM non-compliant ECU 40 itself, that is, the NM non-compliant ECU 40 itself is in a normal state, a sleep state, a sleep possible state, etc. To the circuit 24. Further, when the network management processing circuit 24 shifts the NM non-compliant ECU 40 to the sleep state, the network management processing circuit 24 transmits a sleep signal to the NM non-compliant ECU 40 via the transition signal line 42.
Note that the NM non-compliant ECU 40 transmits only a signal indicating that the NM non-compliant ECU 40 is in a sleepable state to the network management processing circuit 24 via the detection signal line, and the network management processing circuit 24 transmits the transition signal as a transition signal. Only a signal for shifting the NM non-compliant ECU 40 to the sleep state and the normal state may be transmitted via the transition signal line.

  The network management processing circuit 24 executes a network management function such as shifting the NM non-compliant ECU 40 to a sleep state using a ring message received from another NM compatible ECU 30 via the multiplex communication bus 50, and also NM non-NM A ring message indicating the state of the corresponding ECU 40 is created and transmitted to another NM-compatible ECU 30 via the multiplex communication bus 50.

The transmission / reception circuit 25A is connected to the multiplex communication bus 50 via the driver 23A, and is used for normal messages and network management processing for controlling electric devices connected to each ECU with other NM-compatible ECUs 30. The ring message used for the purpose is transmitted and received.
The transmission / reception circuit 25B is connected to the NM incompatible ECU 40 via the driver 23B and the dedicated bus 51, and transmits the normal message received by the gateway device 20 to the NM incompatible ECU 40, and the NM incompatible ECU 40 to the other ECU 30. A normal message to be sent has been received.

The transmission buffer 28 is connected to the transmission / reception circuits 25 </ b> A and 25 </ b> B and to the network management processing circuit 24, and normal messages and ring messages to be transmitted to other NM-compatible ECUs 30 are temporarily stored. Note that the transmission buffer 28 has a storage capacity sufficient to store one message of a normal message or a ring message in order to simplify the circuit.
Similarly to the transmission buffer 28, the reception buffer 27 is connected to the transmission / reception circuits 25A and 25B, and temporarily stores one message of normal messages or ring messages received from other NM-compatible ECUs 30. .

The conflict detection circuit 26 is connected to the transmission / reception circuit 25A, and when the transmission / reception circuit 25A transmits the normal message and the ring message to the multiplex communication bus 50, the other NM-compatible ECUs 30 simultaneously transmit the normal message to transmit the normal message. Arbitration is performed to determine which normal message is preferentially transmitted to the multiplex communication bus 50 in the event of a transmission conflict.
The contention detection circuit 26 is also connected to the transmission / reception circuit 25B, and when a normal message is stored in the reception buffer 27, the transmission / reception circuit 25B is allowed to transmit a pseudo message that is not subject to arbitration. As a result, the gateway device 20 transmits the normal message to the dedicated bus 51 with priority over the ECU 40 that does not support NM.

The power supply 22 is constituted by an LSI which is an integrated circuit, and is connected to the gateway LSI 21 to supply power for driving the gateway LSI 21.
The drivers 23A and 23B are also constituted by LSIs which are integrated circuits, and the driver 23A is connected to the multiplex communication bus 50 via a connector (not shown). Further, it is connected to the gateway LSI 21 and adjusts the potential of the data signal constituting the normal message in order to transmit / receive the normal message transmitted / received by the gateway LSI 21 to / from the multiplex communication bus 50. The driver 23B is connected to the dedicated bus 51 via a connector (not shown).

  Further, the gateway device 20 and the NM incompatible ECU 40 are connected to the ignition key 60, and when the ON signal is input from the ignition key 60, the gateway device 20 and the NM incompatible ECU 40 are activated.

The NM non-compliant ECU 40 includes a driver 45 and is connected to a dedicated bus 51. Further, a power source is built in and used as power for the operation of the ECU 40 that does not support NM. Note that the NM non-compliant ECU 40 may be connected to the power supply 22 provided in the gateway device 20 via a power supply line, and power may be supplied from the gateway device 20.
The other configurations of the NM non-compatible ECU 40 and the NM compatible ECU 30 are the same as those of a general ECU.

Next, the operation of the in-vehicle communication system 10 will be described.
First, the operation when the gateway device 20 and the NM non-compliant ECU 40 receive a normal message from another NM compatible ECU 30 via the multiplex communication bus 50 will be described with reference to the sequence diagram of FIG.
In step S10, the transmission / reception circuit 25A of the gateway device 20 receives the normal message from the multiplex communication bus 50 via the driver 23A.
In step S11, the transmission / reception circuit 25A transmits a normal message to the reception buffer 27, and the reception buffer 27 sequentially stores the normal message from the top.

  In step S12, when the message is stored in the reception buffer 27, the transmission / reception circuit 25B reads the normal message from the reception buffer 27. At this time, the transmission / reception circuit 25B performs transmission by a cut-through method. That is, even when the normal message is not stored in the reception buffer 27 until the end, the transmission / reception circuit 25B reads the normal message and transmits it to the driver 23B when the storage of the normal message in the reception buffer 27 is started. Yes. Note that the normal message may be stored in the reception buffer 27 until the end, and may be performed by a store and forward method in which transmission is started.

In step S <b> 13, the transmission / reception circuit 25 </ b> B transmits a normal message to the dedicated bus 51 via the driver 23 </ b> B of the gateway device 20.
The NM non-corresponding ECU 40 receives a normal message from the dedicated bus 51, determines whether it is a message to be used in its own ECU from the ID of the normal message, and if used, uses the received normal message to determine whether the message is NM not yet used. Control of an electrical device (not shown) connected to the corresponding ECU 40 is performed.

When the transmission / reception circuit 25A transmits a normal message to the multiplex communication bus 50, when another NM-compatible ECU 30 transmits a normal message or a ring message at the same time and a collision occurs, the contention detection circuit 26 Arbitration is performed using the ID of each message, and it is determined whether or not a normal message transmitted by the gateway device 20 is preferentially transmitted to the multiplex communication bus 50. The arbitration is generally performed in the CAN protocol.
When priority is granted to the normal message transmitted by the gateway device 20 through arbitration, the normal message is preferentially transmitted to the multiplex communication bus 50, and when the superiority is inferior, the normal message or ring of another NM-compatible ECU 30 is used. After the message transmission is completed, it is transmitted again.

When the competition detection circuit 26 detects that the normal message is stored in the reception buffer 27, the competition detection circuit 26 causes the transmission / reception circuit 25B to transmit a pseudo message. The pseudo message transmitted to the dedicated bus 51 is a message that cannot be negotiated with other NM incompatible ECUs 40. By transmitting the pseudo message, the NM incompatible ECU 40 transmits a normal message to the dedicated bus 51. Is preventing.
When the transmission / reception circuit 25B is ready to transmit the normal message stored in the reception buffer 27 to the dedicated bus 51, the transmission / reception circuit 25B stops transmitting the pseudo message and transmits the normal message. That is, the gateway device 20 transmits a normal message to the dedicated bus 51 with priority over the NM non-compliant ECU 40.

  When the non-NM-compatible ECU 40 transmits a normal message to another NM-compatible ECU 30, the transmission / reception circuit 25 </ b> B of the gateway device 20 receives the normal message via the dedicated bus 51 and transmits it to the transmission buffer 28. The transmission buffer 28 stores normal messages sequentially from the beginning, and the transmission / reception circuit 25A reads the normal messages from the transmission buffer 28 and transmits them to the multiplex communication bus 50 via the driver 23. The other NM-compatible ECU 30 that has received the normal message from the multiplex communication bus 50 controls an electrical device (not shown) connected to itself by using the normal message.

Next, the operation when the gateway device 20 receives a ring message for the network management function from another NM-compatible ECU 30 via the multiplex communication bus 50 will be described with reference to the sequence diagram of FIG.
In step S20, the transmission / reception circuit 25A of the gateway device 20 receives the ring message via the driver 23A.
In step S21, the transmission / reception circuit 25A transmits a ring message to the reception buffer 27, and the reception buffer 27 stores the ring message.

In step S22, the network management processing circuit 24 reads the ring message from the reception buffer 27. At this time, the network management processing circuit 24 identifies that the message is a ring message from the ID described in the ring message.
The network management processing circuit 24 performs network management processing using the read ring message. For example, when a command for setting each ECU to the sleep state is described in the ring message, the network management processing circuit 24 transmits a sleep signal to the NM non-compliant ECU 40 via the transition signal line 42, and NM non-compliant. The ECU 40 is set to a sleep state.

Next, the operation when the gateway device 20 transmits a ring message to another NM-compatible ECU 30 via the multiplex communication bus 50 will be described with reference to the sequence diagram of FIG.
The NM non-compliant ECU 40 transmits the current operation state of the NM non-compliant ECU 40 to the network management processing circuit 24 of the gateway device 20 via the detection signal line 43. For example, when the NM incompatible ECU 40 is in a sleep capable state, the NM incompatible ECU 40 transmits a signal indicating the sleep capable state to the network management processing circuit 24, and the network management processing circuit 24 receives the signal. The operating state of the NM incompatible ECU 40 is detected.
In step S <b> 30, the network management processing circuit 24 creates a ring message describing the operating state of the NM incompatible ECU 40 and transmits it to the transmission buffer 28.
In step S31, when the ring message is stored in the transmission buffer 28, the transmission / reception circuit 25A reads the ring message from the transmission buffer 28.
In step S32, the ring message is transmitted to the multiplex communication bus 50 via the driver 23A.

  When the gateway device 20 transmits a ring message to the multiplex communication bus 50, when it collides with a normal message or a ring message transmitted by another NM corresponding ECU 30, the conflict detection circuit 26 performs arbitration, and the ring message is transmitted. Whether to preferentially transmit to the multiplex communication bus 50 is determined.

  Further, when an abnormality occurs in the NM non-compliant ECU 40 and the network management processing circuit 24 of the gateway device 20 cannot receive a signal indicating an error state from the NM non-compliant ECU 40 via the detection signal line 43, The indicated signal may not be received. At this time, the network management processing circuit 24 does not transmit the normal message received from the NM incompatible ECU 40 to the multiplex communication bus 50, and causes the NM incompatible ECU 40 to leave the network.

  According to the above configuration, the gateway device 20 having the network management processing circuit 24 is interposed between the NM non-compliant ECU 40 and the multiplex communication bus 50, and the gateway device 20 has a network management function for the NM non-compliant ECU 40. In order to execute, even if it is the vehicle-mounted communication system 10 in which both NM corresponding | compatible ECU30 and NM non-corresponding ECU40 were mixed, a network management system can be performed.

FIG. 5 shows a second embodiment of the present invention.
The connection between the ECU 40 that does not support NM and the gateway device 20 is connected through a dedicated serial communication line 52 and is not connected through the dedicated bus 51. The connection with the serial communication line 52 eliminates the need for the driver 23B of the gateway device 20, thereby simplifying the structure of the gateway device 20 and reducing the cost of the gateway device 20. Moreover, the driver 23 of the ECU 40 that does not support NM is also unnecessary.
Since other configurations and operational effects are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows 1st Embodiment of the vehicle-mounted communication system which is this invention. It is a sequence diagram which shows operation | movement in case a gateway apparatus and NM non-corresponding ECU receive a normal message from another NM corresponding ECU. It is a sequence diagram which shows operation | movement in case a gateway apparatus receives a ring message from other NM corresponding | compatible ECU. It is a sequence diagram which shows operation | movement in case a gateway apparatus transmits a ring message to other NM corresponding | compatible ECU. It is a block diagram which shows 2nd Embodiment.

Explanation of symbols

10 On-vehicle communication system 50 Multiplex communication bus 30 NM-compatible ECU
40 NM non-compliant ECU
20 Gateway device 21 Gateway LSI
22 Power supply 23 (23A, 23B) Driver 24 Network management processing circuit 25 (25A, 25B) Transmission / reception circuit 26 Contention detection circuit 27 Reception buffer 28 Transmission buffer 41 Network management signal line 42 Transition signal line 43 Detection signal line 51 Dedicated bus

Claims (5)

An in-vehicle communication system in which a network management compatible electronic control unit having a network management function and a network management incompatible electronic control unit not having the network management function are connected via a multiplex communication bus,
The network management incompatible electronic control unit and interposed between the multiplex communication bus, comprising a gateway device having a network management processing circuitry to perform the network management functions of the network management incompatible electronic control unit,
The gateway device, in-vehicle communication system, characterized by sending and receiving messages to the network management processing circuits is used between said network management incompatible electronic control unit via the multiplex communication bus. The gateway device is connected to the network management non-compliant electronic control unit via a network management signal line and a dedicated bus or serial communication line,
Via the network management signal line, a signal for executing the network management function is transmitted to and received from the network control incompatible electronic control unit, and
The in-vehicle communication system according to claim 1, wherein the network control non-compliant electronic control unit relays a message transmitted / received to / from the other electronic control unit via a dedicated bus or a serial communication line.   The in-vehicle communication system according to claim 1 or 2, wherein the gateway device is connected to the electronic control unit not supporting network management on a one-to-one basis. The gateway device is
A transceiver circuitry for transmitting and receiving said message,
A conflict detection circuitry to arbitrate when a message collision is transmitted simultaneously to the multiple communication for messages flowing through the bus the network management incompatible electronic control unit sends to the bus for a multiplex communication via the gateway device,
A receiving buffer for storing a message received from the multiplex communication bus,
A transmission buffer for storing the message to be transmitted to the multiplex communication bus,
The in-vehicle communication system according to any one of claims 1 to 3, further comprising: The conflict detection circuit and the network management processing circuit and the reception buffer and the transmission buffer-vehicle communication system according to claim 4 which is formed in an integrated circuit.

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