JP2012191659A - Relay connection unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relay connection unit capable of relaying messages between different onboard LANs as fast as possible.SOLUTION: A relay connection unit includes relay processing means that is connected to a first port and a second port. The relay processing means includes a first buffer and a second buffer disposed between a first reception part and a first transmission part that are connected to the first port and a second reception part and a second transmission part that are connected to the second port. The message received by the first port is stored in the first buffer, sequentially from a part thereof that can be stored, when at least a part of the received message is stored in the first buffer, the stored message can be transmitted from the second port; and the message received by the second port is sequentially stored in the second buffer every time receiving a prescribed length, and from the part stored in the second buffer the message can be transmitted from the first port.

Description

  The present invention relates to an in-vehicle relay connection unit, and more particularly, to a relay connection unit that can relay messages transmitted and received using a plurality of communication lines at high speed.

  In recent years, a large number of electronic control units (ECUs) are mounted on automobiles, and the number thereof tends to increase. Each ECU is configured to be able to construct an in-vehicle LAN by being connected to each other via a communication line, and to send and receive messages between the ECUs. Furthermore, in order to reduce the amount of messages transmitted and received via each communication line, an ECU that connects a plurality of communication lines by a relay connection unit and is connected to a single communication line (a single segment of an in-vehicle LAN) It has been done to reduce the number of.

  FIG. 10 is a diagram schematically showing a configuration of a conventional general relay connection unit 90 shown in “Introduction to CAN” of Non-Patent Document 1. That is, the relay connection unit 90 includes ports 92A and 92B made of in-vehicle LAN communication means connected to communication lines 91A and 91B made of wire harnesses, and a CPU (arithmetic processing unit) 93 connected to the ports 92A and 92B. And a memory 94 for recording relay information indicating the relationship between at least the identification information of the message to be relayed and the relay destination port.

  After receiving all the messages received via the ports 92A and 92B, the CPU 93 sequentially compares the identification information attached to the messages with the identification information included in the relay information recorded in the memory 94, and determines other ports. It is determined whether the message is to be relayed to 92B and 92A. If the CPU 93 determines that the message should be relayed, the message is relayed to the ports 92B and 92A.

  In recent years, it is considered to use an in-vehicle LAN conforming to the FlexRay (registered trademark) standard, which can communicate at higher speed, as a trunk line. For example, when the communication line 91A is a trunk line, a plurality of ECUs 95A, 95B... Are connected together to a communication line 91B compliant with the CAN standard with the communication line 91B as a branch line, and these are connected by the relay connection unit 90 to the trunk line 91A. Configure to connect to. The groups of such ECUs 95A, 95B,... Are connected to the trunk line 91A via the relay connection unit 90, so that another relay connection unit 90 ′ connected to the trunk line 91A and another group via the communication line 91C are connected. It is possible to send and receive messages to and from the group ECUs 95C, 95D.

Introduction to CAN Published: October 1, 2003 Publisher: Renesas Technology Internet (URL: http://www.renesas.com/jpn/products/mpumcu/specific/can_lin_mcu/candoc/rjj99z0001_entry_0400.pdf)

  However, when relaying between in-vehicle LANs having different communication methods using the relay connection unit 90, a unique problem occurs due to the different communication methods of the communication lines 91A and 91B. For example, in the case of FlexRay, a transmission right for transmitting a message to the communication line 91A is periodically assigned, so that more reliable communication can be performed. Therefore, the relay connection unit 90 waits for the transmission right. There is a problem that a delay occurs due to the time.

  FIG. 11 is a diagram for explaining the above-mentioned problem using a time chart. When transmission of a message from one ECU 95A connected to one communication line 91B starts at time Tps, time Tpe when relay connection unit 90 completes reception of this message is time Tp3 when the transmission right of communication line 91A is given. Therefore, the message is relayed to the communication line 91A at the time Tp4 when the next transmission right is given. Therefore, the time point Tpr at which the message starts to be relayed to another communication line 91C may be a time point considerably delayed (three or more cycles in FIG. 11) from the time point Tps at which the ECU 95A starts transmitting.

  As in the relay connection unit 90 shown in Non-Patent Document 1, when the CPU 93 executes the series of processes related to message relay by software, there is a problem that the CPU 93 is required to have a high processing capability. That is, there is a problem that the time until the message arrives at the receiving node is delayed as the amount of messages for determining whether it is necessary to perform relaying handled by the CPU 93 increases. In particular, since in-vehicle LANs tend to become more complex in recent years, a relay connection unit that relays three or more communication lines has become necessary, and the number of messages fetched by the CPU 93 increases. Since this is unavoidable, there is a problem that the delay time for relaying becomes longer.

  The present invention has been made in consideration of the above-described problems, and an object thereof is to provide a relay connection unit capable of relaying messages between different in-vehicle LANs as fast as possible.

In order to solve the above problems, the present invention provides:
A first port connected to a first communication line conforming to the FlexRay standard ;
A second port connected to a second communication line conforming to the CAN standard and having a communication speed lower than that of the first communication line ;
Relay processing means for connecting to the first port and the second port;
The relay processing means includes a first receiver and a first transmitter connected to the first port, a second receiver and a second transmitter connected to the second port, the first receiver and the second A first buffer interposed between the transmitter and a second buffer interposed between the second receiver and the first transmitter;
The received message is sequentially stored in the first buffer from the part where the received message can be received at the first port, and the stored message is transmitted from the second port when at least a part of the received message is stored in the first buffer. As well as
The received message is sequentially stored in the second buffer every time a predetermined length is received at the second port, and the message can be transmitted from the first port from the portion stored in the second buffer. The relay connection unit is provided.

  According to the relay connection unit configured as described above, when receiving a message via the second port, the buffer sequentially stores the received message from the received portion. Then, the reception message stored in the buffer by the relay processing means is transmitted from the portion stored in the buffer via the first port. Therefore, even if the reception message received from the second port is not completely received, the reception message (at least part) up to the portion stored in the buffer at the time when the transmission right of the first communication line is assigned. Can be transmitted to the first communication line. Therefore, even when a message is transmitted to an in-vehicle LAN that needs to wait for transmission of a message until a transmission right is assigned as in the first port communication method, the message can be relayed as fast as possible. That is, the delay time required for message relay can be shortened as much as possible.

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As described above, the buffer includes a first buffer for storing a message received via the first port, and a second buffer for storing a message received via the second port;
The communication speed of the first communication line is higher than the communication speed of the second communication line, and
The relay processing means includes
A first receiving unit for sequentially storing the received message received via the first port in the first buffer from the received part;
At least a part of the message is stored in the second buffer, and when the transmission right of the first communication line is assigned, at least a part of the stored message is passed through the first port. A first transmitter for transmitting;
A second receiving unit for storing in the second buffer each time a predetermined length of a message received via the second port is received;
A second transmission unit configured to transmit the stored message via the second port when at least a part of the message is stored in the first buffer .

  According to the above configuration, when the first receiving unit receives a message via the first port, it stores the received message in the first buffer sequentially from the received part of the received message, so the second transmitting unit stores the received message in the first buffer. When at least a part of the message is stored, a transmission request for starting transmission of the message is generated via the second port. Here, since the communication speed of the first communication line is higher than the communication speed of the second communication line, when the relay processing means transmits a message via the second port, the message to be transmitted is stored in the buffer. The situation that is not done does not occur.

  On the other hand, when the second receiving unit receives a message through the second port, the second transmitting unit stores the predetermined length of the received message in the second buffer every time it receives the message. When at least part of the message is stored and the transmission right of the first communication line is assigned, the message stored in the second buffer is transmitted via the first port. Here, since the received message is stored in the second buffer in a predetermined length unit, the predetermined length is set to the shortest message length that can be transmitted through the first port, so that the first communication line Use efficiency can be improved.

  Since the communication speed of the first communication line is higher than the communication speed of the second communication line, the message received via the second port is divided into a plurality of messages and the transmission right of the first communication line is assigned. Transmitted at a plurality of timings. Therefore, in another relay connection unit connected to the first communication line, when these messages are received, they can be collectively relayed to the second communication line as one message.

  The buffer is divided into a first buffer for storing messages received via the first port and a second buffer for storing messages received via the second port. The flow is not complicated. However, the first buffer and the second buffer may be formed by dividing the area in one buffer. Further, the area division of the first buffer and the second buffer may be dynamically changed. Further, the first and second receivers and the first and second transmitters may be software executed by the relay processing means.

A plurality of second ports connected to the plurality of second communication lines, respectively, the plurality of second ports connected to the relay processing means, and messages transmitted and received between the plurality of second communication lines; It is good also as a structure which can be performed.
The front SL relay processing means includes a relay information storage means for indicating the relationship between the first port or / and the second port comprising identification information of the received message and its relay destination, the received message for each of said identification information The relay process is performed by determining the necessity of relay and the relay destination by comparing the identification information stored in the buffer and the identification information stored in the relay information storage unit with the identification information of the received message. preferable.

  According to the relay connection unit configured as described above, messages are transmitted and received between the first communication line and the plurality of second communication lines or between the plurality of second communication lines. Since the received message and identification information are stored in the buffer, even if there are three or more ports, the message identification information is compared with the identification information stored in the relay information storage means. The necessity of relay and the relay destination can be appropriately determined, and relay transmission can be performed if necessary.

  Furthermore, even when a plurality of messages respectively received from a plurality of second ports are relayed and transmitted to the first port at the same time, it is also possible to send the identification information and the received messages up to the portion where reception has been completed to the first port. Thus, more efficient message relaying can be performed.

The buffer stores a relay destination of each received message;
The relay processing means uses the identification information of each received message stored in the buffer as a relay destination to store information on the first port and / or the second port as a relay destination stored in the relay information storage means. It is preferable to have a relay discrimination unit for storing.

  According to the relay connection unit having the above configuration, the first port and / or the second port serving as a relay destination stored in the relay information storage unit by using the identification information of each received message stored in the buffer by the relay determination unit Is stored in the buffer as the relay destination, and when receiving a message from each port, whether or not the message needs to be relayed when receiving the identification information of each message, and which relay destination It is possible to quickly determine whether relay transmission to a port is necessary. That is, the relay speed can be increased by implementing the relay connection unit in hardware.

  In addition, the relay determination unit in the relay processing unit can be hardwareized by the relay determination unit. That is, since the operations of each part in the relay processing means can be distributed and performed in parallel, it is possible to prevent a decrease in the relay speed from becoming a problem.

  The relay connection unit of the present invention can relay and transmit a received message that has not been received to the end, even if it is a part, when relaying messages between in-vehicle LANs of different communication methods Therefore, the time required for message relay can be shortened as much as possible.

It is a block diagram of the vehicle-mounted LAN using the relay connection unit of 1st Embodiment. It is a block diagram of the said relay connection unit. It is a figure which shows the structure of the buffer provided in the said relay connection unit. It is a figure explaining the process by a 1st receiving part. It is a figure explaining the process by a 1st transmission part. It is a figure explaining the process by a 2nd receiver. It is a figure explaining the process by a 2nd transmission part. It is a figure which shows the example which relays a message using the said relay connection unit. It is a figure explaining the structure of the relay connection unit which concerns on 2nd Embodiment. It is a figure which shows the structure of the conventional relay connection unit. It is a figure which shows the example which relays a message using the conventional relay connection unit.

Hereinafter, embodiments of the relay connection unit 1 of the present invention will be described with reference to the drawings.
1 to 8 are diagrams for explaining a first embodiment of the present invention. FIG. 1 shows a relay connection unit 1 according to the first embodiment (in FIG. 1, each relay connection unit 1 is denoted by reference numerals 1A, 1B... FIG. 2 shows the configuration of the in-vehicle LAN system L formed using the relay connection units 1A, 1B..., When distinction is particularly necessary in the following description, and FIG. FIG. 3 is a diagram illustrating an example of a buffer, FIGS. 4 to 7 are diagrams illustrating detailed operations of each unit, and FIG. 8 illustrates an example of relaying a message m using the relay connection unit 1. FIG.

  In the in-vehicle LAN system L shown in FIG. 1, reference numeral 2 denotes an ECU connected to the relay connection unit 1 (hereinafter, the reference numerals 2A, 2B,..., 2C, 2D,. A first communication line that connects the connection units 1A, 1B,... (In this embodiment, a communication line that conforms to the FlexRay standard), and 4 a second communication line that connects each ECU 2 to the relay connection unit 1 (in this embodiment). This is a communication line that conforms to the CAN standard, and is denoted by reference numerals 4A, 4B,...

  As shown in FIG. 2, the relay connection unit 1 is configured to transmit a message m (the messages ma, mb... Are shown in FIG. 1) to the first communication line 3. A first port 10 comprising means, a second port 11 comprising CAN communication means for transmitting the message m to the second communication line 4, and receiving via the ports 10, 11 connected to the ports 10, 11. Relay processing means 12 that relays and transmits via the ports 11 and 10 from the part that has received the message m.

  Further, the relay processing means 12 includes a first buffer 13a and a second buffer 13b (hereinafter referred to as these buffers) that sequentially store the message m received via the first port 10 or the second port 11 from the part where the message m can be received. 13a and 13b are simply referred to as a buffer 13).

  FIG. 3 is a diagram illustrating the configuration of the first buffer 13a and the second buffer 13b. As shown in FIG. 3, the buffer 13 is roughly divided into an area A of the first buffer 13a and an area B of the second buffer 13b. For each message m, the identification information ID, the message length LEN, the stored message length MLEN, and the data D is associated and stored. The data D portion is configured to be readable and writable by, for example, a FIFO method.

  In addition, the relay processing means 12 stores the received part of the message m received via the first port 10 in the first buffer 13a one by one and the message m in the second buffer 13b. And a first transmission unit 16 that transmits the stored message m via the first port 10 when the transmission right of the first communication line is assigned. A second receiving unit 17 that stores in the second buffer 13b each time a predetermined length of the message m received through the second port 11 is received, and at least a part of the message m in the first buffer 13a Is stored, the second transmission unit 18 that transmits the stored message m through the second port 11, the relationship between the identification information ID of each received message m and the necessity of relaying And a relay information storage unit 19 shown.

  Further, 19a and 19b are first relay destinations to be stored in the relay information storage means 19 using the identification information ID of each received message ma, mb... Received by the first receiver 15 and the second receiver 17. A relay determination unit that refers to the information of the port 10 or the second port 11 and determines whether or not each message ma, mb... Is relayed and stores it in the buffers 13a, 13b. In the present embodiment, since an example is shown in which one each of the first port 10 and the second port 11 are formed in the relay connection unit 1, the determination by the relay determination units 19a and 19b is necessary for the relay. If the relay connection unit 1 has a plurality of second ports 11, the relay information storage means 19 stores the relay destination port information, and the relay discriminating units 19 a and 19 b receive the identification information ID. It is preferable that the port information of the relay destination is determined using (described later).

  On the other hand, the ECU 2 ... has an input / output means 20 for messages ma, mb ..., mc, md ... compliant with the CAN standard, for example, and the first communication line 3 is an in-vehicle LAN that performs time-division communication such as FlexRay. The communication line 4 is a twisted pair cable that complies with the standard of an in-vehicle LAN that performs CSMA / CA communication such as CAN.

  The first communication line 3 transmits and receives the message m at a communication speed of 5 Mbps, and the second communication line 4 is 500 kps. That is, in the present embodiment, the communication speed of the first communication line 3 is sufficiently higher than that of the second communication line 4, and each relay connection unit 1A, 1B constituting the in-vehicle LAN system L using the communication line 4 as a trunk line. .. Are connected to each relay connection unit 1 by CAN so that the message m can be transmitted and received between the ECUs 2A, 2B..., 2c, 2d. Further, since the first communication line 3 is sufficiently faster than the second communication line 4, even if the message m is relayed using the first communication line 3 with the relay connection units 1A, 1B,. A margin can be given to the communication load factor of the line 3.

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  FIG. 4 is a diagram for explaining the operation of the first receiver 15 (hereinafter referred to as “FlexRay receiver”). The process shown in FIG. 4 is executed every time information (hereinafter referred to as reception data) of the message m to be relayed via the first port 10 in the relay connection unit 1 is received in the FlexRay cycle. . Whether or not the message m is to be relayed is determined by the relay determination unit 19b using the identification information ID received via the first port 10.

  Sa1 is a step of storing the received data D in the first buffer 13a. Here, the reception data D constituting each message m is sequentially stored in a different area for each identification information ID of the message m. In the example shown in FIG. 3, the reception data D stored in the first buffer 13a is in bit units, but the reception data D may be stored in units of a predetermined length (for example, 8 bits).

  Sa2 is a step of determining whether or not the received data D stored in the first buffer 13a is the last data. That is, if it is the last data, the process of the next step Sa3 is performed, and if it is not the last data, the process is ended as it is.

  Sa3 is executed when it is determined in step Sa2 that it is the last data, and is a step for executing a data end process. In the process of step Sa3, the accuracy of the received data can be checked using, for example, CRC data attached to the end of the message m.

  The processes of steps Sa1 to Sa3 are continuously executed while the reception process of the reception data is being performed via the first port 10.

  FIG. 5 is a diagram for explaining the operation of the first transmitter 16 (hereinafter referred to as “FlexRay transmitter”). The processing shown in FIG. 5 is executed when a transmission right (hereinafter referred to as a time slot) for transmitting the message m using the first communication line 3 is given to the relay connection unit 1 in the FlexRay cycle.

  Sb1 is a step of determining whether or not at least a part of information (hereinafter referred to as transmission data) of the message m to be transmitted is stored in the second buffer 13b. Then, when it is determined that there is transmission data D, the processing of the subsequent step Sb2 is executed, and when it is determined that there is no transmission data D, the processing ends without doing anything in the current time slot.

  Sb2 is a step of transmitting the transmission data D stored in the second buffer 13b. At this time, since the second buffer 13b stores the information of each part constituting each message ma, mb... As the transmission data D together with its identification information ID, the original message ma, mb. The information of each part constituting ID and the identification information ID are transmitted.

  Sb3 is a step for performing a process of deleting the transmitted data D in the second buffer 13b.

  FIG. 6 is a diagram for explaining the operation of the second receiver 17 (hereinafter referred to as CAN receiver). The process shown in FIG. 6 is executed when the message m is received by the second port 11 in the relay connection unit 1.

  Sc1 is a step of receiving data D constituting message m by a communication protocol compliant with CAN. If it is determined by the relay determining unit 19b that relaying is not necessary for the message m being received in the processing of the receiving step Sc1, the processing is terminated without performing the following steps Sc2. .

  Sc2 is a step of determining whether or not the message m received in step Sc1 has received a predetermined length (8 bits in this embodiment). Here, when the number of received bits is less than 8 bits, the process returns to step Sc1 and is executed, and when 8 bits are received, the next step Sc3 is executed.

  Sc3 is a step of storing in the second buffer 13b information (received data) up to the portion where the message m can be received. The reception data D constituting each message m is sequentially stored in a different area for each identification information ID of the message m.

  Sc4 is a step of determining whether or not the received data stored in the second buffer 13b is the last data and reception of all data to be received from the second communication line 4 has been completed. That is, if it is determined that all data has been received, the process of the next step Sc5 is performed. If it is necessary to receive the subsequent received data, the process returns to step Sc1 and the reception process is continued.

  Sc5 is a step that is executed when it is determined in step Sc4 that all data has been received, and a data end process is executed. In the process of step Sc4, the accuracy of the received data D can be checked using, for example, CRC data attached to the end of the message m.

  FIG. 7 is a diagram for explaining the operation of the first transmitter 18 (hereinafter referred to as CAN transmitter). The processing shown in FIG. 7 is executed when the FlexRay receiving unit 16 starts receiving the message m.

  Sd1 is a step of determining whether or not at least part of information (hereinafter referred to as transmission data D) of the message m to be transmitted is stored in the first buffer 13a. Then, when it is determined that there is transmission data D, the processing of the subsequent step Sd2 is executed, and when it is determined that there is no transmission data, the processing is terminated without doing anything. Here, when there is transmission data corresponding to a plurality of identification information IDs in the first buffer 13a, the following steps Sd2 to Dd5 are repeated for the transmission data D corresponding to one of the identification information IDs. When it is determined in step Sd1 that there is no transmission data D, the process may return to step Sd1 again to wait for transmission data.

  Sd2 is a step of transmitting header information for starting transmission of the message m via the second communication line 4. The header information includes an arbitration field and a control field conforming to the CAN standard, and these are information stored in the first buffer 13a.

  Sd3 is a step of executing a process of transmitting the transmission data stored in the first buffer 13a via the second communication line 4.

  Sd4 is a step of determining whether or not the transmission data D transmitted in step Sd3 has completed transmission of the last transmission data D constituting the message m. If it is determined that transmission of the last transmission data D is completed, the next step Sd5 is executed. If it is determined that there is subsequent transmission data D, the process returns to step Sd3 and repeats the transmission process.

  The first buffer 13a sequentially stores the received data D received by the operation of the FlexRay receiver 15, and the communication speed of the first communication line 3 is higher than the communication speed of the second communication line 4. It is. Therefore, when normal communication is performed, there is a situation in which the transmission data D disappears in the first buffer 13a from the start of transmission of the transmission data constituting one message m to the completion of transmission. It does not occur.

  Sd5 is a step for executing an end process. That is, it is a step of additionally transmitting a redundant term such as CRC data for confirming the accuracy of the message m. That is, this completes the transmission of the message m via the second communication line 4.

  Sd6 is a step of deleting the transmitted data relating to the message m that has been transmitted from the first buffer 13a and releasing the corresponding area of the first buffer 13a.

  As shown in FIG. 1, FIG. 8 connects the relay connection units 1A and 1B to the FlexRay trunk (first communication line 3), and relays the message m using these relay connection units 1A and 1B. Thus, an example in which the message m is transmitted / received between the ECUs 2A, 2B,..., 2C, 2D... Connected to the two second communication lines 4A, 4B will be described.

  As shown in FIG. 8, at time Ts, when one ECU 2 connected to the second communication line 4A transmits the message m, the message m is received by the CAN receiving unit 17 in the relay connection unit 1A, and 8 bits. The received data D1 divided in units is stored in the second buffer 13b.

  The CAN message m starts with header information including information such as an identification information ID that forms an arbitration field of the message m and a message length LEN that forms a control field following the preamble, for example. Therefore, the relay determining unit 19b determines whether or not the message m needs to be relayed when the identification information ID is received, and when it is determined that the message m needs to be relayed, 2 is stored in the buffer 13b and relays a series of data D1, D2,...

  In the example shown in the figure, since reception of only the received data D1 is completed and stored in the second buffer 13b at time T2 when the time slot in which the transmission right of the first communication line 3 is given to the relay connection unit 1A starts, In the time slot starting from T2, the FlexRay transmission unit 16 transmits the transmission data D1 stored in the second buffer 13b to the first communication line 3 as a message m1.

  On the other hand, when the relay connection unit 1B connected to the first communication line 3 receives the data D1, the relay determination unit 19a determines whether it is necessary to relay based on the identification information ID. If it is determined that relaying is necessary, the FlexRay receiving unit 15 starts receiving the first data D1 and stores the data in the first buffer 13a. The CAN transmitter 18 immediately transmits the transmission data D1 stored in the first buffer 13a to the second communication line 4B at time Ts'.

  Similarly, the relay connection unit 1A relays and transmits the subsequent data D2 to D6 as a message m2 collectively at a time T3 when a time slot in which the transmission right of the first communication line 3 is next given to the relay connection unit 1A starts. When the relay connection unit 1B receives this message m1, it relays these data D2 to D6 to the second communication line 4B. Further, the data D7 and D8 are relayed and transmitted as a message m3 at time T4. The messages m1 to m3 generated by dividing the message m include the identification information ID so that it can be understood that all of the messages m1 to m3 are a part of the message m. (In FIG. 7, only the structure of the message m3 is shown in an enlarged view.)

  Further, as shown in FIG. 8, since the communication speed of the first communication line 3 is higher than the communication speed of the second communication lines 4A and 4B, the CAN transmitter 18 of the relay connection unit 1B sends the message m of CAN. When the CAN transmitter 18 needs the next transmission data D2 to D6, D7, and D8, the transmission data D2 to D6, D7, and D8 are stored in the first buffer 13a. Therefore, even when the divided messages m1 to m3 are combined again into one message m and transmitted by the CAN transmitter 18, the situation that the necessary transmission data does not exist in the first buffer 13a occurs. Absent.

  As described above, by using the relay connection unit 1 of the present invention, the relay connection unit 1B relays the message m even when relaying the message m between in-vehicle LANs adopting different communication methods. It is possible to start relay transmission from the time Ts ′ before the time Te at which the transmission of the message m is completed from the ECU 2 that is the transmission source. In particular, it is possible to relay the message m as fast as possible even when the message m is relayed through an in-vehicle LAN in which a transmission right for transmitting the message m to the first communication line is periodically assigned. It is.

  It is useful that the shorter the interval between the start times T1, T2,... Of the time slot to which the transmission right of the first communication line 3 is assigned, the shorter the relay transmission delay time. Further, in order to enable more reliable relaying, it is preferable to use a FlexRay static segment as a time slot to which the transmission right is assigned. A segment may be used.

  FIG. 9 is a diagram illustrating the configuration of the relay connection unit 30 according to the second embodiment. This embodiment differs from the first embodiment shown in FIGS. 1 to 8 in that it is connected to a plurality of second communication lines 4C to 4F and transmits / receives messages me, mf... To / from ECUs 2E to 2H, respectively. The second port 11a to 11d is provided. The relay information storage means 19 in the relay processing means 12 stores relay destination port information (information for identifying the first port 10 and the second ports 11a to 11d) for each identification information ID of each message m. ing.

  By using the relay connection unit 30 configured as in the present embodiment, it is possible to relay and transmit the message m between the second communication lines 4C to 4F, and each second communication line 4C. Since the amount of the message m to be transmitted / received using ~ 4F can be reduced, a problem such as a collision does not occur even when a large amount of data is transmitted / received. In addition, when necessary, the message m can be relayed and transmitted to / from another relay connection unit (not shown) via the first communication line 3, and the relay delay time can be shortened as much as possible. can do.

1 (1A, 1B) Relay connection unit 2 (2A, 2B ...) ECU
3 First Communication Line 4 Second Communication Line 10 First Port 11 Second Port 13 Buffer 13a First Buffer 13b Second Buffer 15 First Receiver 16 First Transmitter 17 Second Receiver 18 Second Transmitter 19 Relay Information storage means 19a, 19b Relay discrimination unit

Claims (4)

A first port connected to a first communication line conforming to the FlexRay standard;
A second port connected to a second communication line conforming to the CAN standard and having a communication speed lower than that of the first communication line;
Relay processing means for connecting to the first port and the second port;
The relay processing means includes a first receiver and a first transmitter connected to the first port, a second receiver and a second transmitter connected to the second port, the first receiver and the second A first buffer interposed between the transmitter and a second buffer interposed between the second receiver and the first transmitter;
The received message is sequentially stored in the first buffer from the part where the received message can be received at the first port, and the stored message is transmitted from the second port when at least a part of the received message is stored in the first buffer. As well as
A relay connection unit configured to sequentially store a received message at the second port every time a predetermined length is received by the second buffer and to transmit a message from the portion stored in the second buffer from the first port. .   The relay connection unit according to claim 1, wherein transmission can be started at a time prior to completion of transmission of a message from a transmission source.   A plurality of second ports connected to the plurality of second communication lines, respectively, the plurality of second ports connected to the relay processing means, and messages transmitted and received between the plurality of second communication lines; The relay connection unit according to claim 1 or 2, wherein the relay connection unit can be configured.   The relay connection unit according to any one of claims 1 to 3, wherein the first communication line and the second communication line are made of a twisted pair cable.

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