Communication control device, communication control method, and communication control program

Abstract

Provided is a communication control device for controlling communication in an on-vehicle network to which there are connected a first on-vehicle device connected to a first power supply and a second on-vehicle device connected to a second power supply. The communication control device comprises a processor. The processor executes an operation including: a step in which the second power supply is detected to have been turned on while the first power supply is turned on; and a step in which, when it is detected that the second power supply has been turned on while the first power supply is turned on, timing information relating to the timing at which the second on-vehicle device is to start transmission of frames is transmitted to the second on-vehicle device on the basis of a periodically arriving reference time for the first on-vehicle device to transmit frames and the activation time of the second on-vehicle device.

Description

Communication Control Device, Communication Control Method, and Communication Control Program

[0001] The present disclosure relates to a communication control device, a communication control method, and a communication control program. This application claims priority based on Japanese Application No. 2024-232571 filed on December 27, 2024, and incorporates all the contents described in the above Japanese application.

[0002] Vehicles are equipped with various in-vehicle devices such as a control system ECU (Electronic Control Unit) that controls an engine, transmission, etc., a body system ECU that controls headlights, power windows, etc., an information system ECU such as a navigation device and multimedia equipment. Each in-vehicle device is connected to an in-vehicle network and can communicate with each other.

[0003] In Patent Document 1, in an in-vehicle system in which an information processing device, which is an in-vehicle device, is connected by an in-vehicle LAN (Local Area Network) using Ethernet (registered trademark) via a relay device that is an in-vehicle relay device, a technique is disclosed in which the relay device corrects the transmission timing of packets by the information processing device. The relay device disclosed in Patent Document 1 receives a packet transmitted from the information processing device, acquires the transmission timing of the packet by the information processing device by referring to scheduling data, calculates the difference between the acquired transmission timing and the reception timing of the packet, and when the absolute value of the calculated difference is greater than or equal to a threshold value, transmits a correction request for correcting the subsequent transmission timing by the calculated difference to the information processing device.

[0004] Japanese Patent Application Laid-Open No. 2019-047163

[0005] A communication control device according to one aspect of the present disclosure is a communication control device that controls communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, and comprises a processor, the processor performing an operation that includes the steps of: detecting that the second power supply has been turned on while the first power supply is turned on; and, when it is detected that the second power supply has been turned on while the first power supply is turned on, transmitting timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device begins transmitting a frame, based on a periodically occurring reference time for the first in-vehicle device to transmit a frame and the startup time of the second in-vehicle device.

[0006] Figure 1 is a block diagram showing an example of the configuration of an in-vehicle system according to the embodiment. Figure 2 is a block diagram showing an example of the hardware configuration of a relay ECU according to the embodiment. Figure 3 is a diagram illustrating the frame transmission cycle. Figure 4 is a diagram showing an example of the configuration of a management table. Figure 5A is a diagram illustrating the determination of the transmission start reference time. Figure 5B is a diagram illustrating the determination of the transmission start reference time. Figure 6 is a flowchart showing the communication control processing by the relay ECU according to the embodiment.

[0007] ECUs are classified by the type of power supply they are connected to, for example, +B, IG, or ACC. Each ECU starts up when the connected power supply is turned on, so the startup timing of ECUs connected to the same power supply is the same. On the other hand, since the timing of turning on each power supply is determined by the driver's operation, the startup timing of each ECU is arbitrary for each type of power supply. Therefore, when a group of ECUs connected to the first power supply (e.g., +B) is running, the group of ECUs connected to the second power supply (e.g., IG) starts up when the second power supply is turned on, and begins transmitting data at the timing determined for their respective devices. The data transmission timing of each ECU is scheduled to smooth out communication traffic, but because the power supply is turned on at a timing unrelated to the data transmission schedule, data transmission may not occur according to schedule, and data transmission by multiple ECUs may be concentrated in a short period, potentially increasing the network load.

[0008] In the technology disclosed in Patent Document 1 mentioned above, if data transmission from multiple information processing devices does not occur according to schedule, the relay device will send correction requests to each of the information processing devices individually, which may further increase the network load.

[0009] According to this disclosure, it is possible to set the timing of data transmission by in-vehicle devices while suppressing network load.

[0010] The embodiments of this disclosure are outlined below.

[0011] (1) The communication control device according to this embodiment is a communication control device that controls communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, and comprises a processor, the processor performing an operation that includes the step of detecting that the second power supply has been turned on while the first power supply is turned on, and when it is detected that the second power supply has been turned on while the first power supply is turned on, the processor transmits timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device starts transmitting frames, based on a periodically occurring reference time for the first in-vehicle device to transmit frames and the startup time of the second in-vehicle device. This makes it possible to set the timing of data transmission by the second in-vehicle device while suppressing the network load.

[0012] (2) In (1) above, the timing information may be information indicating the time until a future reference time. This makes it possible to control the frame transmission of the first in-vehicle device and the frame transmission of the second in-vehicle device using the same reference time.

[0013] (3) In (2) above, the timing information may be information for instructing the prohibition of transmitting the frame until the future reference time. By prohibiting frame transmission from the second in-vehicle device until the future reference time, the timing of frame transmission from the second in-vehicle device can be set.

[0014] (4) In (2) or (3) above, the future reference time may be the (n+1)th reference time if the end time of the startup time falls between the nth reference time and the (n+1)th reference time, where n is an integer. This allows frame transmission from the second onboard device to start from the next reference time after the startup time has ended.

[0015] (5) In any one of (1) to (4) above, the startup time may be the maximum startup time among the startup times of each of the multiple second in-vehicle devices. This makes it possible to set the transmission timing of the multiple second in-vehicle devices by the maximum startup time.

[0016] (6) In any one of (1) to (5) above, the transmission may include broadcasting the timing information. This makes it possible to set the frame transmission timing of multiple second in-vehicle devices at once.

[0017] (7) The communication control method according to this embodiment is a communication control method for controlling communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, and includes the steps of: detecting that the second power supply has been turned on while the first power supply is turned on; and, when it is detected that the second power supply has been turned on while the first power supply is turned on, transmitting timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device starts transmitting frames, based on a periodically occurring reference time for the first in-vehicle device to transmit frames and the startup time of the second in-vehicle device. This makes it possible to set the timing of data transmission by the second in-vehicle device while suppressing the network load.

[0018] (8) The communication control program according to this embodiment is a communication control program for controlling communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, and causes a computer to perform the steps of: detecting that the second power supply has been turned on while the first power supply is turned on; and, when it is detected that the second power supply has been turned on while the first power supply is turned on, transmitting timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device starts transmitting frames, based on a periodically occurring reference time for the first in-vehicle device to transmit frames and the startup time of the second in-vehicle device. This makes it possible to set the timing of data transmission by the second in-vehicle device while suppressing the network load.

[0019] This disclosure can be implemented not only as a relay device having the characteristic configuration described above, a communication control method using characteristic processing in the relay device as a step, and a communication control program that causes the relay device to execute characteristic processing, but also as an in-vehicle system including the relay device, or as part or all of the relay device being implemented as a semiconductor integrated circuit.

[0020] The embodiments of the present invention will be described in detail below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0021] [1. In-vehicle system] Figure 1 is a block diagram showing an example of the configuration of an in-vehicle system according to the embodiment. The in-vehicle system 100 is mounted on a vehicle.

[0022] The in-vehicle system 100 relating to this implementation includes a relay ECU 200 and ECUs 310A, 320B, 320C, 310D, and 320E. The in-vehicle system 100 also includes an in-vehicle network consisting of the relay ECU 200, ECUs 310A, 320B, 320C, 310D, and 320E, and communication lines (communication buses) 400A and 400B connecting them.

[0023] Multiple ECUs 310A, 320B, 320C, 310D, and 320E are placed in various parts of the vehicle. ECUs 310A, 320B, 320C, 310D, and 320E individually control the hardware of each part of the vehicle or monitor the status of the hardware of each part of the vehicle. For example, ECUs 310A, 320B, 320C, 310D, and 320E are control system, body system, and information system ECUs. ECUs 310A, 320B, 320C, 310D, and 320E are an example of an "in-vehicle device".

[0024] The vehicle is equipped with a battery 500. Battery 500 is an auxiliary battery that supplies power to the relay ECU 200 and ECUs 310A, 320B, 320C, 310D, and 320E. Power lines extend from battery 500 and are connected to the constant power supply, +B power supply 510. Battery 500 is also connected to the IG power supply 520 via the IG relay 600.

[0025] Each of the relay ECUs, 200, 310A, and 310D, is connected to the +B power supply 510 via a power line. ECUs 310A and 310D are examples of the "first on-board device". Hereinafter, ECUs 310A and 310D will be collectively referred to as the "+B system ECU 310". Each of the ECUs, 320B, 320C, and 320E, is connected to the IG power supply 520 via a power line. ECUs 320B, 320C, and 320E are examples of the "second on-board device". Hereinafter, ECUs 320B, 320C, and 320E will be collectively referred to as the "IG system ECU 320". ECUs 310A, 320B, 320C, 310D, and 320E will be collectively referred to as the "ECU 310, 320".

[0026] The relay ECU 200 is connected to ECUs 310A, 320B, 320C, 310D, and 320E respectively via communication buses 400A and 400B. Communication buses 400A and 400B are, for example, CAN buses. Specifically, ECUs 310A, 320B, and 320C are connected to communication bus 400A. ECUs 310D and 320E are connected to communication bus 400B. Each of the ECUs 310A, 320B, and 320C connected to communication bus 400A can communicate with each other via communication bus 400A. Each of the ECUs 310D and 320E connected to communication bus 400B can communicate with each other via communication bus 400B.

[0027] Each of the relay ECUs 200 and 310, 320 uses a communication protocol for periodically or aperiodically sending and receiving frames. The communication protocol is, for example, CAN. The communication protocol may be CAN FD (CAN with Flexible Data Rate) or CAN XL. The communication protocol may also be Ethernet. If Ethernet is used, the in-vehicle network may be configured in a star network topology.

[0028] The relay ECU 200 functions as a gateway that relays communication between multiple ECUs 300. The relay ECU 200 relays frames between ECUs connected to different buses. That is, ECUs 310A, 320B, and 320C connected to communication bus 400A and ECUs 310D and 320E connected to communication bus 400B can communicate with each other via the relay ECU 200. For example, the relay ECU 200 can relay frames between ECU 310A connected to bus 400A and ECU 310D connected to bus 400B.

[0029] [2. Hardware Configuration of the Relay ECU] Figure 2 is a block diagram showing an example of the hardware configuration of the relay ECU according to the embodiment. The relay ECU 200 includes a processor 201, a non-volatile memory 202, a volatile memory 203, communication interfaces (hereinafter also referred to as "communication I / F") 204A, 204B, and a power supply circuit 205. The relay ECU 200 is an example of a "communication control device". The processor 201, the non-volatile memory 202, the volatile memory 203, the communication I / F 204A, 204B, and the power supply circuit 205 are each connected to a data bus 206.

[0030] The volatile memory 203 is a semiconductor memory such as SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory). The non-volatile memory 202 is a flash memory, hard disk, ROM (Read Only Memory), etc. The non-volatile memory 202 stores the communication control program 210, which is a computer program, and the data used to execute the communication control program 210. The functions of the relay ECU 200, which will be described later, are performed when the communication control program 210 is executed by the processor 201.

[0031] The processor 201 is, for example, a CPU (Central Processing Unit). However, the processor 201 is not limited to a CPU. The processor 201 may also be a GPU (Graphics Processing Unit). In a specific example, the processor 201 is a multi-core processor. The processor 201 may also be a single-core processor. The processor 201 is configured to execute computer programs. However, the processor 201 may also be, for example, an ASIC (Application Specific Integrated Circuit), or programmable hardware such as an FPGA (Field Programmable Gate Array) or a CPLD (Complex Programmable Logic Device). In this case, the ASIC or programmable hardware is configured to execute the same functions as the communication control program 210.

[0032] Communication interfaces 204A and 204B are communication interfaces that conform to the communication protocol described above. Communication interfaces 204A and 204B are, for example, CAN interfaces.

[0033] Communication interface 204A is connected to bus 400A. Communication interface 204B is connected to bus 400B. Relay ECU 200 can communicate with ECUs 310A, 320B, and 320C via communication interface 204A. Relay ECU 200 can communicate with ECUs 310D and 320E via communication interface 204B.

[0034] The non-volatile memory 202 stores the management table 220. The management table 220 is used by the communication control program 210. The management table 220 will be described later.

[0035] The power supply circuit 205 is connected to the +B power supply 510 and the IG power supply 520. The power supply circuit 205 converts the voltage output from the +B power supply 510 and supplies the converted power to the processor 201, non-volatile memory 202, volatile memory 203, and communication I / F 204A and 204B, respectively. When the IG relay 600 switches from the off state to the on state and the IG power supply 520 is turned on, the power supply circuit 205 detects, for example, a change in the output voltage from the IG power supply 520. When the power supply circuit 205 detects that the IG power supply 520 has been turned on, it outputs an IG signal to the processor 201.

[0036] [3. Offset] Each of the ECUs 310 and 320 periodically transmits frames. Figure 3 is a diagram illustrating the frame transmission period. The frame transmission period is common to both ECUs 310 and 320. The frame transmission period P_T is defined by periodically occurring reference times t0, t1, t2, t3, ... The reference times t0, t1, t2, t3, ... repeat at regular time intervals. One transmission period P_T is the period from one reference time (e.g., t0) to the next reference time (e.g., t1) following that reference time.

[0037] Each of the ECUs 310 and 320 has an offset OF set individually for frame transmission. The offset OF is the period from the reference time t0, t1, t2, t3, ... to the time tr1, tr2, tr3, ... when the ECUs 310 and 320 transmit frames. The offset OF is a period shorter than one transmission cycle P_T. The offset OFs of the ECUs 310 and 320 are set so that multiple frame transmissions are not concentrated in a short period but are distributed within the frame transmission cycle.

[0038] Figure 4 shows an example of the configuration of the management table. Figure 4 also shows an example of the offset settings for ECUs 310 and 320. In the example in Figure 4, the offset for ECU 310A is set to "2ms", the offset for ECU 320B is set to "7ms", the offset for ECU 320C is set to "5ms", the offset for ECU 310D is set to "10ms", and the offset for ECU 320E is set to "3ms".

[0039] [4. Functions of the Relay ECU] Returning to Figure 2, the communication control program 210 includes multiple codes that can be executed by the processor 201. The processor 201 executes the detection process 211, the calculation process 212, the decision process 213, and the transmission process 214 based on the communication control program 210.

[0040] The detection process 211 is a process that detects when the IG power supply 520 is turned on while the +B power supply 510 is turned on. Since the processor 201 is driven by the +B power supply 510, the +B power supply 510 is turned on when the processor 201 is operating. Therefore, the processor 201 does not need to determine whether the +B power supply 510 is turned on or not, and only needs to detect when the IG power supply 520 is turned on. In a specific example, the processor 201 detects when the IG power supply 520 is turned on by detecting the IG signal output from the power supply circuit 205.

[0041] The calculation process 212 calculates the reference time for when the IG-system ECU 320 starts transmitting frames (hereinafter also referred to as the "transmission start reference time") based on the periodically occurring reference time for the +B-system ECU 310 to transmit frames and the startup time of the IG-system ECU 320.

[0042] In a specific example, the transmission start reference time is the same as one of the future reference times. For example, calculation process 212 calculates the reference time that will arrive after all IG system ECUs 320 are ready to transmit frames. More specifically, calculation process 212 calculates the reference time that will arrive after all IG system ECUs 320 have finished starting up.

[0043] In the calculation process 212, the processor 201 determines the time when the startup of all IG system ECUs 320 is completed (that is, the time when the startup of the ECU that is the last to complete startup among all IG system ECUs 320 is completed). For example, the processor 201 determines the maximum startup time among the startup times of all IG system ECUs 320. The processor 201 determines the time when the determined maximum startup time has elapsed from the time when the IG power supply 520 is turned on (hereinafter, also referred to as the "IG on time") as the time when the startup of all IG system ECUs 320 is completed (hereinafter, also referred to as the "startup completion time"). The startup completion time is an example of the "end time of the startup time").

[0044] The processor 201 identifies the maximum startup time among the startup times of the IG system ECUs 320 based on the management table 220. Refer to FIG. 4. The management table 220 stores the CAN ID, offset, power supply, bus, and startup time of each ECU 310, 320. In the example of FIG. 4, the CAN ID of ECU 310A is "0x100", the CAN ID of ECU 320B is "0x110", the CAN ID of ECU 320C is "0x120", the CAN ID of ECU 310D is "0x210", and the CAN ID of ECU 320E is "0x220". The power supply of ECU 310A is "+B", the power supply of ECU 320B is "IG", the power supply of ECU 320C is "IG", the power supply of ECU 310D is "+B", and the power supply of ECU 320E is "IG". The bus of ECU 310A is "400A", the bus of ECU 320B is "400A", the bus of ECU 320C is "400A", the bus of ECU 310D is "400B", and the bus of ECU 320E is "400B". The startup time of ECU 310A is "50 ms", the startup time of ECU 320B is "80 ms", the startup time of ECU 320C is "70 ms", the startup time of ECU 310D is "80 ms", and the startup time of ECU 320E is "90 ms".

[0045] For example, the processor 201 refers to the "Power" field in each record of the management table 220, and identifies the record in which "IG" is stored. The processor 201 reads the information stored in the "Startup Time" field of the identified record, and identifies the maximum startup time from the read startup times. In the example of FIG. 4, the startup time "90 ms" of the ECU 320E is the maximum startup time among the startup times of the IG system ECUs 320.

[0046] Returning to FIG. 2, in the calculation process 212, the processor 201 calculates a future reference time that arrives after the determined startup completion time as the transmission start reference time. FIGS. 5A and 5B are diagrams for explaining the determination of the transmission start reference time. When the startup time completion time is between the nth reference time and the (n + 1)th reference time, the processor 201 calculates the (n + 1)th reference time as the transmission start reference time. That is, when the next reference time is after the transmission start reference time, the processor 201 calculates the next reference time as the transmission start reference time. When the next reference time is before the transmission start reference time and the next and subsequent reference times are after the transmission start reference time, the processor 201 calculates the next and subsequent reference times as the transmission start reference time.

[0047] In FIGS. 5A and 5A, the horizontal axis represents time, and t0, t1, and t2 are each reference times. The IG power supply 520 is turned on at the time t_IG after the reference time t0. The time ct after the maximum startup time ST has elapsed from the IG on time t_IG is the startup completion time when the startup of all the IG system ECUs 320 is completed.

[0048] In the example of FIG. 5A, the startup completion time ct is before the next reference time t1 of the reference time t0. That is, the first reference time that arrives after the startup completion time ct is the reference time t1. In this case, the reference time t1 is determined as the transmission start reference time.

[0049] In the example in Figure 5B, the startup completion time ct is after the next reference time t1 following reference time t0, and before the next reference time t2 following reference time t1. That is, the first reference time that arrives after the startup completion time ct is reference time t2. In this case, reference time t2 is determined as the transmission start reference time.

[0050] Returning to Figure 2, the decision process 213 is the process of determining a transmission prohibition period that prohibits frame transmission from the IG system ECU 320, which is activated when the IG power supply 520 is turned on. Referring to Figures 5A and 5B, in a specific example, the processor 201 determines the period from the IG on time t_IG to the transmission start reference time as the transmission prohibition period PR. In the example in Figure 5A, the period from the IG on time t_IG to the reference time t1 is the transmission prohibition period PR. In the example in Figure 5B, the period from the IG on time t_IG to the reference time t2 is the transmission prohibition period PR.

[0051] Returning to Figure 2, the transmission process 214 is the process of sending timing information to the IG system ECU 320 regarding the timing at which the IG system ECU 320 will start transmitting frames. The timing information is, for example, information indicating the time until a future reference time, and specifically, information indicating the transmission prohibition period PR.

[0052] The processor 201 broadcasts the transmission ban period PR. Here, "broadcasting" means sending a broadcast frame. This allows all ECUs 310 and 320 to be notified of the transmission ban period PR.

[0053] When the IG-system ECU 320 receives a transmission prohibition period PR, it prohibits frame transmission from the IG-on time t_IG until the transmission prohibition period PR ends. The IG-system ECU 320 sets the end time of the transmission prohibition period PR as the reference time. In other words, the IG-system ECU 320 transmits a frame after the offset set for its own device has elapsed from the moment the transmission prohibition period PR ends.

[0054] For example, for the +B system ECU 310, the transmission ban period PR is unnecessary information. For instance, when the +B system ECU 310 receives a broadcast frame containing the transmission ban period PR, it discards the received broadcast frame. The +B system ECU 310 will transmit a frame even during the transmission ban period PR when the frame transmission timing set for its device (i.e., the timing after the offset from the reference time) arrives.

[0055] [5. Operation of the relay ECU] The operation of the relay ECU 200 according to this embodiment will be described below.

[0056] Figure 6 is a flowchart showing the communication control process by the relay ECU according to the embodiment.

[0057] The processor 201 determines whether or not it has detected the IG power supply 520 being turned on (step S101). That is, the processor 201 determines whether or not it has detected the output of the IG signal from the power supply circuit 205. If the processor 201 has not detected the IG power supply 520 being turned on (NO in step S101), it executes step S101 again.

[0058] When the processor 201 detects that the IG power supply 520 has been turned on (YES in step S101), it refers to the management table 220 and determines the maximum startup time among the startup times of the IG system ECU 320 (step S102).

[0059] The processor 201 calculates the startup completion time ct of the IG system ECU 320 from the time it detected the IG power supply 520 was turned on (IG on time) and the determined maximum startup time (step S103).

[0060] The processor 201 sets the next reference time to the target time ot (step S104). The processor 201 compares the target time ot with the startup completion time ct and determines whether the target time ot is later than the startup completion time ct (step S105).

[0061] If the target time ot is before the startup completion time ct (NO in step S105), the processor 201 sets the next reference time (the first reference time that occurs after the target time ot) to the target time ot (step S106). After that, the processor 201 returns to step S105.

[0062] If the target time ot is after the startup completion time ct (YES in step S105), the processor 201 determines the period from the IG on time t_IG to the startup completion time ct as the transmission prohibition period PR (step S107). The processor 201 broadcasts the determined transmission prohibition period PR (step S108). This completes the communication control process.

[0063] [6. Modifications] In the above embodiment, the transmission start reference time was set to the first reference time that occurs after the startup completion time ct of the IG system ECU 320, but the embodiment is not limited to this. The transmission start reference time may be set to reference times that occur multiple times after the startup completion time ct of the IG system ECU 320.

[0064] In the above embodiment, the ECUs 310 and 320 included in the in-vehicle system 100 were powered by two power sources, a +B power supply 510 and an IG power supply 520, but the system is not limited to this. For example, the ECUs may be powered by an ACC power supply different from the +B power supply 510 and the IG power supply 520. In this case, the relay ECU 200 may detect the power being turned on when the +B power supply 520 is turned on, determine the startup completion time of the ECU connected to the ACC power supply (hereinafter also referred to as the "ACC system ECU"), and use the reference time that arrives after the startup completion time as the transmission start reference time for the ACC system ECU, and transmit a transmission prohibition period to the ACC system ECU.

[0065] In the above embodiment, the communication control device is the relay ECU 200, but it is not limited to this. An ECU other than the relay ECU 200 may be used as the communication control device. For example, an ECU that functions as a communication control device may be provided for each of the buses 400A and 400B.

[0066] [7. Supplementary Notes] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and includes the meaning of equivalents of the claims and all modifications within that scope.

[0067] 100 In-vehicle system 200 Relay ECU 201 Processor 202 Non-volatile memory 203 Volatile memory 204A, 204B Communication interface (communication I / F) 205 Power supply circuit 206 Data bus 210 Communication control program 211 Detection process 212 Calculation process 213 Decision process 214 Transmission process 220 Management table 310 +B system ECU 320 IG system ECU 310A, 320B, 320C, 310D, 320E ECU 400A, 400B Communication bus 500 Battery 510 +B power supply 520 IG power supply 600 IG relay

Claims

1. A communication control device for controlling communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, comprising a processor, the processor performing operations including: detecting that the second power supply has been turned on while the first power supply is turned on; and, when the second power supply has been detected to have been turned on while the first power supply is turned on, transmitting timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device begins transmitting a frame, based on a periodically occurring reference time for the first in-vehicle device to transmit a frame and the startup time of the second in-vehicle device.

2. The communication control device according to claim 1, wherein the timing information is information indicating the time until a future reference time.

3. The communication control device according to claim 2, wherein the timing information is information for instructing the prohibition of transmitting the frame until the future reference time.

4. The future reference time is the (n+1)th reference time if the end time of the startup time falls between the nth reference time and the (n+1)th reference time, as described in claim 2 or 3, where n is an integer.

5. The communication control device according to any one of claims 1 to 4, wherein the startup time is the maximum startup time among the startup times of each of the multiple second in-vehicle devices.

6. The communication control device according to any one of claims 1 to 5, wherein the transmission includes broadcasting the timing information.

7. A communication control method for controlling communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, comprising: a step of detecting that the second power supply has been turned on while the first power supply is turned on; and a step of transmitting timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device begins transmitting a frame, based on a periodically occurring reference time for the first in-vehicle device to transmit a frame and the startup time of the second in-vehicle device, when it is detected that the second power supply has been turned on while the first power supply is turned on.

8. A communication control program for controlling communication in an in-vehicle network to which a first in-vehicle device connected to a first power supply and a second in-vehicle device connected to a second power supply are each connected, the program causing a computer to perform the following steps: detecting that the second power supply has been turned on while the first power supply is turned on; and, when it is detected that the second power supply has been turned on while the first power supply is turned on, transmitting timing information to the second in-vehicle device regarding the timing at which the second in-vehicle device begins transmitting a frame, based on a periodically occurring reference time for the first in-vehicle device to transmit a frame and the startup time of the second in-vehicle device.

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