Relay system

Abstract

To suppress delay in relay processing of a communication message conforming to a second communication protocol in a relay system that converts a communication message conforming to a first communication protocol into a communication message conforming to the second communication protocol and transmits the converted message.SOLUTION: A relay system 1 has a function of converting an Ethernet message received on a first communication bus 30 into multiple CAN messages and transferring them to a third communication bus 50, and a function of relaying a CAN message received on a second communication bus 40 to the third communication bus 50. The relay system 1 relays the CAN message received on the second communication bus 40 to the third communication bus 50 while limiting the number of transmissions of the multiple CAN messages converted from the Ethernet message to an upper transmission limit number, in one transmission process determined at a predetermined time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a relay system that converts a communication message conforming to a first communication protocol having a relatively long data length into a communication message conforming to a second communication protocol having a relatively short data length and transmits the converted message. [Background technology]

[0002] Patent Document 1 discloses a relay device that, when converting and transferring a message conforming to the Ethernet (registered trademark, the same applies hereinafter) protocol into a message conforming to the CAN (registered trademark, the same applies hereinafter) protocol, determines the relay target not on a message frame basis but on a type of information included in the message frame in response to a relay request from the destination ECU, and relays the message.The relay device of Patent Document 1 suppresses relaying of information included in the frame that is not requested, thereby reducing the amount of communication on the bus to which the destination ECU is connected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-96251 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, unlike the relay device described in Patent Document 1, if the relay system converts all of the data portions of a message conforming to the Ethernet protocol (hereinafter referred to as an Ethernet message) into multiple messages conforming to the CAN protocol (hereinafter referred to as CAN messages) and transfers them continuously, a problem may arise in which delays occur in the relay processing of normal CAN messages.

[0005] In other words, because the data length of an Ethernet message can be set much longer than the data length of a CAN message, once transmission of multiple CAN messages converted from Ethernet messages begins, it takes a long time to complete transmission of all CAN messages.If the relay system also has a function to relay normal CAN messages whose destination is the same communication bus as the destination of the multiple converted CAN messages, it will not be able to relay the normal CAN messages to the destination communication bus during that time, and there is a risk of delays in the relay processing of the normal CAN messages.

[0006] The present disclosure has been made in consideration of the above-mentioned points, and aims to suppress delays in relay processing of communication messages conforming to a second communication protocol in a relay system that converts communication messages conforming to a first communication protocol having a relatively long data length into communication messages conforming to a second communication protocol having a relatively short data length and transmits the converted message. [Means for solving the problem]

[0007] In order to achieve the above object, a relay system according to the present disclosure is a relay system that converts a communication message conforming to a first communication protocol having a relatively long data length into a communication message conforming to a second communication protocol having a relatively short data length, and transmits the converted message to a first communication bus (50), The relay system also has a relay function of transmitting a communication message conforming to the second communication protocol received via the second communication bus (40) to the first communication bus; a conversion unit (14) that performs a process for converting a communication message conforming to a first communication protocol into a plurality of communication messages conforming to a second communication protocol; a storage unit (24) for temporarily storing a plurality of converted data items converted by the conversion unit; a transmitter (52, 54) for transmitting, to the first communication bus, a communication message based on the plurality of conversion data stored in the storage unit and a communication message received via the second communication bus; and a processing unit (26) that executes processing to transmit, via the transmitting unit, communication messages based on the plurality of converted data stored in the storage unit and communication messages received via the second communication bus, while limiting the number of transmitted communication messages based on the plurality of converted data stored in the storage unit to an upper transmission limit number in a single transmission process set at a predetermined time.

[0008] Since the relay system according to the present disclosure has the above-described configuration, the number of transmissions of communication messages based on the plurality of conversion data stored in the storage unit in one transmission process is limited to the upper transmission limit number, thereby suppressing delays in relay processing of communication messages received via the second communication bus, i.e., delays in transmission of the communication messages.

[0009] 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.

[0010] 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]

[0011] [Figure 1] 1 is a configuration diagram showing the overall configuration of a network system including a relay system according to a first embodiment. [Figure 2] 2 is an explanatory diagram illustrating an example of a message relay process in the relay system shown in FIG. 1; FIG. [Figure 3] 5 is a flowchart showing processing executed in a transmission processing unit according to the first embodiment. [Figure 4] 4 is a time chart for explaining the effects of the first embodiment. [Figure 5] 6 is a time chart for explaining the effects of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of a network system including a relay system according to the present disclosure will be described with reference to the drawings. The following embodiments merely illustrate examples of the present disclosure. Therefore, the numerical values, components, component arrangements and connection configurations, as well as the processing contents and order of steps (processes) shown in the following embodiments may be changed as desired. Furthermore, the same reference numerals may be used throughout the drawings to omit descriptions of identical or similar configurations. When only a portion of a configuration is described in each embodiment, the configurations of other previously described embodiments may be applied to the remaining portions of the configuration. Furthermore, configurations of multiple embodiments may be partially combined, even if not explicitly described, as long as there is no particular problem with the combination, in addition to the combinations explicitly described in the description of each embodiment.

[0013] (First embodiment) 1 is a configuration diagram showing the overall configuration of a network system including a relay system 1 according to this embodiment. The relay system 1 according to this embodiment is applied to, for example, a network system established in a vehicle. However, application examples of the relay system 1 according to the present disclosure are not limited to in-vehicle network systems, and it can also be applied to other uses (for example, a network system for managing a building).

[0014] 1, the relay system 1 includes a communication controller 32 and a communication interface (I / F) 34 connected to a first communication bus 30, a communication controller 42 and a communication I / F 44 connected to a second communication bus 40, and a communication controller 52 and a communication I / F 54 connected to a third communication bus 50. The communication controller 52 and the communication I / F 54 correspond to the transmitting unit of the present disclosure.

[0015] Each communication controller 32, 42, 52 has a function of temporarily storing a communication message when it receives the communication message from the respective communication bus 30, 40, 50. Furthermore, when transmitting a communication message, the communication controller 32, 42, 52 has a function of temporarily storing the communication message to be transmitted and transmitting the stored communication message when the corresponding communication bus 30, 40, 50 becomes free. The communication controller 32, 42, 52 may be configured by hardware or a combination of hardware and software.

[0016] The communication I / Fs 34, 44, and 54 have a function of passing a received communication message to the gateway device 10 when the received communication message is stored in the corresponding communication controller 32, 42, or 52.

[0017] Furthermore, when transmitting a communication message, the communication I / F 34, 44, 54 passes a PDU corresponding to the message to be transmitted, which is provided by the relay processing unit 12, to the communication controller 32, 42, 52. The communication controller 32, 42, 52 temporarily stores the received PDU as a communication message until it is transmitted to the corresponding communication bus. The communication I / F 34, 44, 54 may be configured by software or hardware. Alternatively, the communication I / F 34, 44, 54 may be configured by a combination of hardware and software.

[0018] Furthermore, the relay system 1 of this embodiment includes a gateway device 10. The gateway device 10 is connected to the first communication bus 30, the second communication bus 40, and the third communication bus 50 via the above-mentioned communication controllers 32, 42, 52 and communication I / Fs 34, 44, 54.

[0019] The first communication bus 30 is connected to, for example, a communication device that communicates with the outside world or a port to which a vehicle diagnostic device is connected, and is used to send and receive communication messages (Ethernet messages) conforming to the Ethernet protocol. The second and third communication buses 40 and 50 are connected to various electronic control units (ECUs) and sensors installed in the vehicle. These second and third communication buses 40 and 50 are used to send and receive communication messages (CAN messages) conforming to the CAN protocol. The various ECUs and sensors are grouped by control function, such as body control, powertrain control, chassis control, and entertainment control, or by area in the vehicle, and each group is connected to a different communication bus. The number of communication buses is not limited to the example shown in FIG. 1 , and more communication buses may be connected to the gateway device 10. Alternatively, multiple gateway devices 10 may be provided for more communication buses, distributing the relay function of the gateway device 10.

[0020] The gateway device 10 includes a relay processing unit 12 and an unpacking processing unit 14. The relay processing unit 12 has a table that indicates the relationship between, for example, the MAC address, IP address, and / or port number of an Ethernet message, the message ID of a CAN message, the communication bus on which the message was received, and the destination to which the received message is to be sent. For example, if the type of the received message is an Ethernet message, the relay processing unit 12 can refer to the table to determine whether the received Ethernet message is a message to be unpacked, which includes multiple CAN communication protocol data units (PDUs), each of which corresponds to a CAN message. If the relay processing unit 12 determines based on the table that the Ethernet message is to be unpacked, it sends the Ethernet message to the unpacking processing unit 14, as shown in FIG. 2.

[0021] For example, when a communication device receives an Ethernet message containing traffic information transmitted from an external device, the communication device transmits the received Ethernet message to the gateway device 10 via the first communication bus 30. The gateway device 10 converts the received Ethernet message into a CAN message and transfers the converted message to a communication bus connected to, for example, a navigation ECU that controls the operation of a navigation device. This enables the navigation ECU to perform operations such as displaying congested sections on a screen or searching for detours based on the transferred communication message. This is just one example of converting an Ethernet message into a CAN message and transferring it. The gateway device 10 can also convert various types of Ethernet messages into CAN messages and transfer them.

[0022] Furthermore, if the type of the received message is a CAN message, relay processing unit 12 refers to the table and determines the destination communication bus corresponding to the message ID, etc. Then, relay processing unit 12 sends the received CAN message (PDU) to transmission control unit 20 corresponding to the determined communication bus, as shown in FIG.

[0023] For example, when two or more ECUs connected to the second communication bus 40 and the third communication bus 50 need to execute cooperative control in which they operate in cooperation with each other, an ECU connected to the second communication bus 40 may transmit a communication message to an ECU connected to the third communication bus 50, the communication message including information necessary to execute the cooperative control (such as its own control content, control instructions for the cooperative control, and control timing). When the gateway device 10 receives such a communication message via the second communication bus 40, it performs a relay process so that the received communication message is sent to an ECU connected to the third communication bus 50. However, this is merely an example of a CAN message relay process performed by the gateway device 10. The gateway device 10 can also perform various other CAN message relay processes.

[0024] 1 and 2 show a configuration in which a transmission control unit 20 is provided for the third communication bus 50, but if it is necessary to transfer Ethernet messages to other communication buses such as the second communication bus 40, it is desirable to provide a transmission control unit 20 for the other communication bus. Furthermore, although not shown in FIG. 1, when the gateway device 10 converts a received CAN message into an Ethernet message by protocol conversion and transmits it, the gateway device 10 may have a packing processing unit that packs multiple PDUs included in the CAN message into the data portion of the Ethernet message. In this case, the gateway device can determine the PDU header of the Ethernet message from the ID of the CAN message and store it in the PDU of the Ethernet message.

[0025] The unpacking unit 14 corresponds to the converter of the present disclosure. As shown in FIG. 2 , the unpacking unit 14 divides a message received from the relay processing unit 12 into multiple CAN communication PDUs and outputs them to the transmission control unit 20 via the relay processing unit 12. At this time, the unpacking unit 14 may output the divided PDUs to the transmission control unit 20 as is, or, if necessary, may perform processing such as adding a PDU header before outputting them to the transmission control unit 20. For example, if an Ethernet message always contains a fixed number of PDUs of the same type in a predetermined order, a PDU header may not be necessary. On the other hand, if an Ethernet message contains any number of PDUs of any type, the unpacking unit 14 may add a PDU header including, for example, an ID and a data length. Here, the length of the data portion of an Ethernet message is, for example, approximately 1500 bytes, while the length of a PDU of a CAN message is a maximum of 8 bytes. Therefore, as part of the protocol conversion process, the data portion of the Ethernet message is divided into multiple CAN message PDUs.

[0026] The transmission control unit 20 includes, for example, a first standby buffer 22, a second standby buffer 24, and a transmission processing unit 26. As shown in FIG. 2, the first standby buffer 22 stores PDUs of CAN messages received via the second communication bus 40. The second standby buffer 24 corresponds to the storage unit of the present disclosure. As shown in FIG. 2, the second standby buffer 24 stores multiple PDUs divided by the unpacking processing unit 14. The transmission processing unit 26 corresponds to the processing unit of the present disclosure. The transmission processing unit 26 executes a process of transmitting a message including a PDU stored in the first standby buffer 22 and a message including a multiple PDU stored in the second standby buffer 24 via the communication I / F 54 and the communication controller 52, as shown in FIG. 2, while limiting the number of messages including the multiple PDUs stored in the second standby buffer 24 to an upper transmission limit number in a single transmission process determined at a predetermined time. The upper transmission limit number may be a predetermined fixed number. The transmission processing unit 26 may be implemented by software executed by a processor such as a CPU, a GPU, or a DFP.

[0027] Note that, when the gateway device 10 is connected to a communication bus for transmitting and receiving CAN messages in addition to the second communication bus 40, the first standby buffer 22 may also store PDUs of CAN messages received from that communication bus. Alternatively, the transmission control unit 20 may be provided with a plurality of first standby buffers 22, one for each communication bus for transmitting and receiving CAN messages. Similarly, when there are a plurality of communication buses for transmitting and receiving Ethernet messages, the transmission control unit 20 may store a plurality of divided PDUs in a single second standby buffer. Alternatively, the transmission control unit 20 may be provided with a plurality of second standby buffers 24, one for each communication bus for transmitting and receiving Ethernet messages. Furthermore, although FIGS. 1 and 2 show an example in which the transmission control unit 20 is provided external to the gateway device 10, the transmission control unit 20 may be built into the gateway device 10.

[0028] Next, the processing executed in transmission processing unit 26 will be described in detail with reference to the flowchart in Fig. 3. The processing shown in the flowchart in Fig. 3 is executed periodically at a predetermined cycle. The execution time of one transmission process is set to a time equal to or less than the time interval of the predetermined cycle.

[0029] In the first step S100, the transmission processing unit 26 checks whether PDUs, which are data to be transmitted, are stored in the first and second standby buffers 22, 24. Then, in step S110, the transmission processing unit 26 determines whether there is a message to be transmitted based on whether PDUs are stored in the first and second standby buffers 22, 24. If a PDU is stored in at least one of the first standby buffer 22 and the second standby buffer 24, the transmission processing unit 26 determines that there is a message to be transmitted, and proceeds to step S120. On the other hand, if the transmission processing unit 26 determines that no PDUs are stored in either the first standby buffer 22 or the second standby buffer 24 and that there is no message to be transmitted, it proceeds to step S220.

[0030] In step S120, the transmission processing unit 26 determines whether PDUs are stored in both the first and second standby buffers 22, 24 and whether it is necessary to transmit a message including PDUs stored in the multiple standby buffers 22, 24. If it is determined that it is necessary to transmit a message including PDUs stored in the multiple standby buffers 22, 24, the transmission processing unit 26 proceeds to step S140. On the other hand, if it is determined that it is not necessary to transmit a message including PDUs stored in the multiple standby buffers 22, 24 and that it is sufficient to transmit only a message including PDUs stored in one standby buffer, the transmission processing unit 26 proceeds to step S130.

[0031] In step S130, the transmission processing unit 26 executes a process of reading the PDU from the standby buffer 22 or 24 in which the PDU is stored, and sending the PDU to the communication I / F 54. That is, if the PDU is stored in the first standby buffer 22, the transmission processing unit 26 reads the PDU from the first standby buffer 22 and sends it to the communication I / F 54. As a result, the communication controller 52 generates a message including the PDU sent to the communication I / F 54, and sends the message. Hereinafter, the PDU stored in the first standby buffer 22 may be referred to as a normal PDU.

[0032] On the other hand, if the PDU is stored in the second standby buffer 24, the transmission processing unit 26 reads the PDU from the second standby buffer 24 and transmits it to the communication I / F 54. As a result, the communication controller 52 generates a message including the PDU sent to the communication I / F 54 and transmits the message. Hereinafter, the PDU stored in the second standby buffer 24 may be referred to as a divided PDU.

[0033] Note that when only the second standby buffer 24 stores PDUs, the transmission processing unit 26 can transmit the multiple divided PDUs stored in the second standby buffer 24 to the communication I / F 54 in excess of the upper transmission limit. In this case, there are no messages containing normal PDUs to be transmitted other than the messages containing the divided PDUs, so there is no need to consider delays in transmitting messages containing normal PDUs. However, the time required for one transmission process is set to a predetermined time, and messages containing divided PDUs that cannot be transmitted within this predetermined time will be transmitted in subsequent transmission processes.

[0034] In step S140, the transmission processing unit 26 determines a transmission priority for each message containing a PDU stored in the multiple standby buffers 22, 24. This transmission priority can be determined, for example, based on a message ID. For example, a priority can be assigned to each message ID in advance. The transmission processing unit 26 can then determine a transmission priority for each message containing a PDU stored in the multiple standby buffers 22, 24 based on the predetermined priority of each message ID. Alternatively, the transmission processing unit 26 may determine the transmission priority based on the timing at which each PDU was stored in the multiple standby buffers 22, 24, such that a message containing a PDU that was stored earlier has a higher priority than a message containing a PDU that was stored later.

[0035] In step S150, the transmission processing unit 26 determines whether the transmission priority of the message including the segmented PDU stored in the second standby buffer 24 is higher than the transmission priority of the message including the normal PDU stored in the first standby buffer 22. If it is determined that the transmission priority of the message including the segmented PDU stored in the second standby buffer 24 is higher, the transmission processing unit 26 proceeds to step S160. On the other hand, if it is determined that the transmission priority of the message including the normal PDU stored in the first standby buffer 22 is higher, the transmission processing unit 26 proceeds to step S190.

[0036] In step S160, the transmission processing unit 26 executes a process of transmitting a message including the divided PDU. That is, the transmission processing unit 26 executes a process of reading the divided PDU from the second standby buffer 24 and sending it to the communication I / F 54. As a result, the communication controller 52 generates a message including the PDU sent to the communication I / F 54, and transmits the message.

[0037] In step S170, the transmission processing unit 26 determines whether the number of transmitted messages including the segmented PDUs has reached the upper transmission limit. If the number of transmitted messages including the segmented PDUs has not reached the upper transmission limit, the process of transmitting the message including the segmented PDU in step S160 is repeated. If the number of transmitted messages including the segmented PDUs reaches the upper transmission limit by repeating the process of transmitting the message including the segmented PDU in step S160, the transmission processing unit 26 proceeds to step S180. In step S180, the transmission processing unit 26 executes a process of transmitting a message including a normal PDU. That is, the transmission processing unit 26 executes a process of reading the segmented PDU from the first standby buffer 22 and sending it to the communication I / F 54. As a result, the communication controller 52 generates a message including the PDU sent to the communication I / F 54, and transmits the message. Thereafter, the transmission processing unit 26 proceeds to step S220.

[0038] In step S190, the transmission processing unit 26 executes processing to transmit the message including the normal PDU first, since the message including the normal PDU has a higher transmission priority. Thereafter, in step S200, the transmission processing unit 26 executes processing to transmit the message including the segmented PDU. In step S210, similar to step S170, the transmission processing unit 26 determines whether the number of transmitted messages including the segmented PDU has reached the upper transmission limit. If the number of transmitted messages including the segmented PDU has not reached the upper transmission limit, the processing of step S200 to transmit the message including the segmented PDU is repeated. If the number of transmitted messages including the segmented PDU has reached the upper transmission limit, the transmission processing unit 26 proceeds to step S220.

[0039] In step S220, the transmission processing unit 26 determines whether or not it is time to end the current transmission process. If it is not time to end the transmission process, the transmission processing unit 26 returns to the process of step S100 and executes the processes of S100 to S210 described above. If it is time to end the transmission process, the transmission processing unit 26 ends the process shown in the flowchart of FIG.

[0040] Next, the effects of this embodiment will be described in more detail with reference to the time chart of Fig. 4. Fig. 4 shows an example of how Ethernet messages and CAN messages are relayed by the control processing of the transmission control unit 20.

[0041] As shown in Fig. 4, when an Ethernet message is received on the first communication bus 30 and a CAN message is received on the second communication bus 40, a decision is made as to which message containing a PDU should be given priority for transmission. Fig. 4 shows an example in which transmission of a message containing a divided PDU of an Ethernet message is given priority. The data portion of the Ethernet message is unpacked by the unpacking processing unit 14 of the gateway device 10 and divided into a plurality of divided PDUs. The plurality of divided PDUs are then stored in the second standby buffer 24 of the transmission control unit 20 and transmitted as a message containing divided PDUs via the communication IF 54 and the communication controller 52.

[0042] Here, if all messages including multiple segmented PDUs are transmitted consecutively, a problem may occur in that, if the number of segmented PDUs is large, delays may occur in the transmission of messages including normal PDUs of CAN messages. Therefore, in this embodiment, as shown in FIG. 4 , the transmission processing unit 26 executes a process of transmitting messages including segmented PDUs and normal PDUs while limiting the number of messages including multiple segmented PDUs stored in the second standby buffer 24 to the upper transmission limit during a single transmission process determined at a predetermined time. As a result, since the number of messages including segmented PDUs is limited to the upper transmission limit during a single transmission process determined at a predetermined time, messages including normal PDUs can also be transmitted. Therefore, according to this embodiment, it is possible to suppress delays in relaying messages including normal PDUs of CAN messages received via the second communication bus 40, i.e., delays in the transmission of messages including normal PDUs.

[0043] If there is still time to send additional messages before the end of the transmission processing time even after sending a message including a normal PDU, the message including the remaining fragmented PDUs may be sent. Also, as shown in Figure 4, if the transmission processing time has almost expired due to the transmission of a message including a normal PDU, the message including the remaining fragmented PDUs will be sent during the next transmission processing.

[0044] (Second embodiment) Next, a relay system 1 according to a second embodiment of the present disclosure will be described. The relay system 1 according to this embodiment has almost the same configuration as the relay system 1 according to the first embodiment, and therefore a description of the configuration will be omitted.

[0045] In the relay system 1 according to the first embodiment described above, an example has been described in which the upper transmission limit limiting the number of messages including a segmented PDU that can be transmitted during a single transmission process is set to a predetermined fixed number. In contrast, in the relay system 1 according to the present embodiment, the transmission control unit 20 determines the upper transmission limit limiting the number of messages including a segmented PDU that can be transmitted by monitoring the communication load or communication volume (communication traffic) of the third communication bus 50, which is the transmission destination of the messages including the segmented PDU. The transmission control unit 20 is configured to change the upper transmission limit limit depending on the results of monitoring the communication traffic.

[0046] Specifically, the transmission control unit 20 sets the upper limit number of transmissions when the monitoring result of the communication traffic on the third communication bus 50 indicates a high bus load to be lower than the upper limit number of transmissions when the monitoring result indicates a low bus load. This makes it possible for the communication controller 52 to suppress delays in the transmission of messages containing normal PDUs, even when there is a large amount of communication traffic and some waiting time occurs before a message is transmitted.

[0047] The effects of this embodiment will be described in more detail with reference to the time chart of Fig. 5. Fig. 5 shows an example of how an Ethernet message and a CAN message are relayed according to the bus load of the third communication bus 50 by the control process of the transmission control unit 20. Fig. 5 also shows an example in which a message including a divided PDU of an Ethernet message is transmitted with priority over a message including a normal PDU of a CAN message.

[0048] 5, when the result of monitoring communication traffic indicates a low bus load, the transmission control unit 20 maintains the upper transmission limit number, which limits the number of transmitted messages including segmented PDUs, at the initial upper transmission limit number. This is because when the bus load is low, even if the number of transmitted messages including segmented PDUs is restricted by the initial upper transmission limit number during one transmission process, and a relatively large number of messages including segmented PDUs are transmitted, there is a high possibility that messages including normal PDUs may also be transmitted.

[0049] On the other hand, when the communication traffic monitoring results indicate a high bus load, the transmission control unit 20 reduces the upper transmission limit, which limits the number of messages containing segmented PDUs, from the initial upper transmission limit. If the upper transmission limit, which limits the number of messages containing segmented PDUs, remains the initial upper transmission limit even when the bus load is high, there is a possibility that messages containing normal PDUs cannot be transmitted if a wait time occurs in transmitting a message containing multiple segmented PDUs. Therefore, in this embodiment, when the bus load is high, the upper transmission limit is reduced from the initial upper transmission limit. This increases the possibility that messages containing normal PDUs can be transmitted even in a high bus load environment.

[0050] The above describes 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 of the gist of the present disclosure.

[0051] For example, in the above-described embodiment, an example has been described in which the gateway device 10 receives an Ethernet message from the first communication bus 30, receives a CAN message from the second communication bus 40, and transfers these messages to the third communication bus 50. That is, in the above-described embodiment, an example has been described in which a communication message conforming to a first communication protocol having a relatively long data length is an Ethernet message, and a communication message conforming to a second communication protocol having a relatively short data length is a CAN message.

[0052] However, the first communication protocol is not limited to the Ethernet protocol, and the second communication protocol is not limited to the CAN protocol. In short, when the data length of the first communication protocol and the data length of the second communication protocol are different and a communication message conforming to the first communication protocol is divided into multiple messages when converted into a message conforming to the second communication protocol, the relay system 1 according to the present disclosure can be applied. [Explanation of symbols]

[0053] 1: relay system, 10: gateway device, 12: relay processing unit, 14: unpacking processing unit, 20: transmission control unit, 22: first waiting buffer, 24: second waiting buffer, 26: transmission processing unit, 30: first communication bus, 32: communication controller, 34: communication I / F, 40: second communication bus, 42: communication controller, 44: communication I / F, 50: third communication bus, 52: communication controller, 54: communication I / F

Claims

1. A relay system that converts a communication message conforming to a first communication protocol having a relatively long data length into a communication message conforming to a second communication protocol having a relatively short data length and transmits the converted message to a first communication bus (50), The relay system also has a relay function of transmitting a communication message conforming to the second communication protocol received via a second communication bus (40) to the first communication bus; a conversion unit (14) that performs processing to convert a communication message conforming to the first communication protocol into a plurality of communication messages conforming to the second communication protocol; a storage unit (24) for temporarily storing a plurality of converted data items converted by the conversion unit; a transmitting unit (52, 54) that transmits, to the first communication bus, a communication message based on the plurality of conversion data stored in the storage unit and a communication message received via the second communication bus; a processing unit (26) that executes a process of transmitting, via the transmitting unit, communication messages based on the plurality of converted data stored in the storage unit and communication messages received via the second communication bus, while limiting the number of transmissions of communication messages based on the plurality of converted data stored in the storage unit to an upper transmission limit number in a single transmission process determined at a predetermined time.

2. The relay system according to claim 1 , wherein the processing unit changes the upper limit number of transmissions in accordance with a result of monitoring communication traffic on the first communication bus.

3. 3. The relay system according to claim 2, wherein the processing unit sets the upper limit number of transmissions when the monitoring result of the communication traffic of the first communication bus indicates a high bus load to be lower than the upper limit number of transmissions when the monitoring result indicates a low bus load.

4. 4. The relay system according to claim 1, wherein the processing unit, when no communication message is received via the second communication bus, transmits a communication message based on the plurality of conversion data stored in the storage unit, exceeding the upper transmission limit number.

5. 4. The relay system according to claim 1, wherein when there are communication messages based on a plurality of conversion data stored in the storage unit and communication messages received via the second communication bus, the processing unit determines an order in which to send each of the communication messages, and transmits the corresponding communication messages in accordance with the determined order.

6. 6. The relay system according to claim 5, wherein the processing unit determines the order in which the communication messages are transmitted depending on the type of each communication message and / or the timing at which each communication message is received.

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