JP2008042690A - Relay connection unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relay connection unit which achieves a high speed relay of message and controls the relay of an error message. <P>SOLUTION: The unit includes a plurality of ports to transmit and receive the message, a buffer to store reception messages to receive through the ports by turns, a relay information recording means to record a relation between an identification information of the message to be relayed and a relay destination port, a reception error monitoring means to detect a bit error of the message to be received and to calculate a bit error generation rate each port and/or each identification information, an error rate recording means to record the calculated bit error generation rate each port and/or each identification information, and a relay processing means to receive the identification information of the reception message, to judge the transit destination port corresponding to the identification information by comparing it with the identification information stored in the relay information recording means and to obtain a relay starting time to start a relay transmission of the reception message based on the bit error generation rate of a reception port recorded in the error rate recording means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an in-vehicle relay connection unit, and more particularly, to a relay connection unit that relays messages transmitted and received using a plurality of communication lines at high speed without waste.

  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 connected to each other via a communication line to construct an in-vehicle LAN so that messages can be transmitted and received between the ECUs. Furthermore, in order to reduce the amount of messages transmitted / received via each communication line, an ECU that connects a plurality of communication lines by a relay connection unit and is connected to one communication line (a single segment of the in-vehicle LAN) It has been done to reduce the number of.

  FIG. 12 is a diagram showing a configuration of a conventional general relay connection unit 90 shown in “Introduction to CAN” of Non-Patent Document 1. As shown in the figure, 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 CPUs (arithmetic processing) connected to the ports 92A and 92B. And a memory 94 in which relay information indicating the relationship between at least the identification information of the message to be relayed and the relay destination port is recorded.

  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. When the CPU 93 determines that the message should be relayed, the message is relayed to the ports 92B and 92A.

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)

  As in the relay connection unit 90 disclosed in Non-Patent Document 1, when the CPU 93 executes the series of processes related to message relay by software, there arises 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 message to be determined 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 taken into the CPU 93 increases. Since this is unavoidable, there is a problem that the delay time for relaying becomes longer.

In addition, after the CPU 93 has received the received message, the relay destination ports 92A and 92B are discriminated using the identification information, and when relaying is necessary, relay transmission is started, so at least one message is transmitted. It was inevitable that the relay transmission would be delayed for the time required for.
Therefore, in order to shorten the delay time required for relaying as much as possible, it is desirable to perform processing in which the CPU 93 relays and transmits the message being received to a port that requires the message in parallel. However, in the relay using the CPU 93 where processing is concentrated, it is very difficult to shorten the time required for relay transmission by parallel processing.

Further, among the messages received by the relay connection unit 90, there is a message containing an error due to a malfunction of the transmission source ECU. Moreover, what is not exact | accurate by the influence of the noise etc. which mixed on communication line 91A, 91B is contained.
For this reason, in the conventional relay connection unit 90, when a message including an error is relayed, there arises a problem that the communication load on the communication line of the relay destination is unnecessarily increased.

  The present invention has been made in view of the above problems, and provides a relay connection unit capable of relaying messages as fast as possible and minimizing the relay of useless messages containing errors as much as possible. It is an issue.

In order to solve the above problems, the present invention provides:
A plurality of ports comprising in-vehicle LAN communication means for transmitting and receiving messages; and
A buffer for sequentially storing received messages received via the port from a received part;
A relay information recording means for recording the relationship between the identification information of the message that needs to be relayed and the relay destination port;
A reception error monitoring means for detecting a bit error of a message received through the port and obtaining a bit error occurrence rate for each port or / and for each identification information;
An error rate recording means for recording a bit error occurrence rate for each port or / and each identification information obtained by the reception error monitoring means;
The relay destination port corresponding to the identification information is determined by comparing with the identification information recorded in the relay information recording means at the time of receiving the identification information of the received message, and recorded in the error rate recording means The relay start time for starting the relay transmission of the received message is determined according to the bit error occurrence rate of the reception port, and stored in the buffer when the reception error monitoring means does not detect a bit error until the relay start time. Relay processing means for relaying transmitted messages;
The relay connection unit is provided.

The relay processing unit preferably has a function of canceling relay transmission of a message when the reception error monitoring unit detects a bit error before the relay start time.
Further, it is preferable that the relay processing unit has a function of canceling relay transmission when a bit error occurs in a message being relayed.
As described above, when a bit error occurs, by canceling the relay transmission, it is possible to minimize the time required to send a useless message to the communication line as the relay destination.

In the relay connection unit of the present invention, the reception error monitoring means obtains a bit error occurrence rate (bit error rate) for each message reception port or / and for each identification information, and for each port or / and each identification information bit. Record the error rate in the error rate recording means.
Normally, when performing data communication, a redundant term (redundant bit) is added to prevent the same signal from being transmitted continuously more than a predetermined number, and information such as parity check is periodically mixed. ing. Therefore, the reception error monitoring means can detect in real time that an error has occurred in the received message by confirming these redundant terms.

The relay processing means determines a relay start time for starting relay transmission of a message in the buffer for each reception port or / and for each identification information based on the bit error rate.
For example, the relay processing means relays the time when the message having the number of relay delay bits is received, using relay delay time setting information in which the relationship between the bit error occurrence rate and the delay time (for example, the number of bits to be delayed) is tabulated in advance. The starting point is.
If a bit error occurs in the received message before the relay start time, as described above, the relay transmission of the message is stopped, and the optimum delay time is set according to the status of the port receiving the message. After elapses, relay processing of the message being received is started.

The delay time refers to the delay time from the shortest time when the port receives the identification information of the received message and relay transmission is possible to the time when relay start is possible.
Further, the optimum delay time is a probability Y () in which a bit error occurs and the relay connection unit relays an error message from the start of relay until it is confirmed that the message has been correctly received. This is a time for delaying the relay start time so that the error occurrence rate) can be set to an acceptable low probability, for example, 9 × 10 ⁻⁸ or less. This error occurrence rate Y can be expressed by equation (1) when the bit error rate is 10 ^−X .
Y = N × 10 ^−X Formula (1)
(Where N is the number of remaining bits that have not been received at the start of relaying)

Usually, depending on the environment of a communication line (including not only a wired communication line such as a CAN bus but also wireless) connected to each port, it is inevitable that a bit error occurs with a predetermined probability due to the influence of noise or the like. .
However, in the present invention, the reception error monitoring means multiplies the current bit error rate for each port by multiplying a predetermined constant, for example, by reversing the time interval at which a bit error occurs, or the past. It is obtained by using the number of bit errors that have occurred several times or within a predetermined time in the past, and the relay start time for each port is determined from the equation (1) using the obtained bit error rate.
As described above, in the present invention, the relay processing means determines the bit error rate for each reception port and determines the relay start time, thereby relaying the message being received from the relay start time as early as possible by parallel processing. be able to. In addition, by adjusting the relay start time so that the probability that the message started from the relay start time becomes an error message becomes extremely small, this does not cause a significant deterioration in the communication load factor in the communication line of the relay destination .

  The reception error monitoring means also obtains the bit error rate for each identification information of the message in the same manner as the bit error rate for each port, and records the bit error rate for each identification information in the error rate recording means. The relay processing means determines the relay start time for starting relay transmission of the message in the buffer for each identification information based on the bit error rate.

The port is used to send and receive messages conforming to various in-vehicle LAN standards such as CAN, and the buffer is a memory configured to read and write messages to be sent and received bit by bit, such as a flip-flop. It is preferable to collect a variety of bit storage elements.
Similarly, it is preferable that the relay information recording means is a memory configured to be readable at high speed, and has a bus capable of accessing at high speed a portion storing identification information in the buffer. Further, the relay processing means is preferably a logic circuit configured to be able to access the buffer and the relay information recording means at high speed, and a comparator for comparing the identification information in the buffer and the identification information recorded in the relay information recording means It is preferable to have such a logic circuit.

Since the relay processing of the message by the relay connection unit having the above-described configuration can be performed simply by sequentially transferring the message from the buffer to each relay destination port, the parallel processing for relaying and transmitting the message being received can be easily performed. Can do.
When the error is equal to or higher than a predetermined probability, it is preferable to complete the reception of the message and to relay the message in the buffer after confirming the accuracy of the message.

In the present invention, buffer management means for managing the storage area in the buffer divided into a plurality of slot areas;
It is preferable that a transmission management unit that relays and transmits a message corresponding to the transmittable port by using a buffer management unit when each port is in a transmittable state.

The buffer management means includes
When a message to be stored in the buffer is received from each port, the slot area in which a space is generated is searched, and information indicating that the slot area is in use is stored, and then the slot area is stored. The message being received is stored one by one, and the relay destination port of the message and the relay start time determined by the relay processing means are stored when the identification information of the message has been stored.
Further, when receiving a request for relay transmission of a message from the transmission management means, a slot for storing a message to be output to a relay destination port which is in a transmittable state by sequentially tracing each slot area in use After the area is searched and the message stored in the slot area is relayed and transmitted to the relay destination port, the information of the relay destination port in the slot area is deleted.
Furthermore, it is preferable that when there is no relay destination port stored in the slot area, it is stored that the slot area is an empty slot and the slot area is released.

With the above configuration, when a received message is input via a port, the buffer management means secures an empty slot area in the buffer, and the message is stored in this empty slot area.
Further, since the relay processing unit compares the identification information with the identification information stored in the relay information recording unit when the identification information is received, the relay destination port and the relay start time are determined. And the relay start time is stored in the slot area.
When the relay destination port is not set, reception of this message is interrupted, and the buffer management means stores that the slot area is an empty slot and releases the slot area.

  Next, when the port is in a transmittable state, a message corresponding to the transmittable port is selected using the output destination information stored in the slot area and output to the port. That is, it is possible to relay a message being received when the identification information is received.

  The information indicating that the slot area is in use or free is stored in each slot area in use by sequentially storing information indicating the position of the next slot area, thereby sequentially linking the slot areas in use. It is preferable that the information be linked to the chain structure and managed. As a result, a large number of slot areas shared by each port can be integrated and managed. It is also possible to check the usage status of each slot area using flag information.

  The relay connection unit of the present invention monitors a bit error for each port or / and for each identification information, and for a message received from a port having a high bit error occurrence rate or / and a message for identification information having a high bit error occurrence rate, Since the relay start time is determined so that the relay start of this message is delayed from the fastest time at which relay transmission is possible, for messages with a low bit error occurrence rate, the message being received is relayed as fast as possible by parallel processing. can do. On the other hand, when a message with a high bit error occurrence rate is relayed and transmitted by parallel processing, relay transmission is started from a relay start time with an appropriate delay time according to the bit error occurrence rate. Therefore, it is possible to reduce the occurrence of a situation where an error message is unnecessarily relayed and transmitted due to a bit error.

  In the present invention, message relay processing including error message processing is not controlled by software such as an operation program, but is performed using ports, buffers, and relay information recording means that can be realized with simple hardware. Yes. Therefore, compared to the conventional case where relay processing is performed by a CPU that operates by software, the relay processing means that executes processing by hardware performs bit information input / output processing in parallel by electronic circuits distributed for each port. Pipeline processing is possible, so there is almost no processing delay due to an increase in the number of ports. In addition, since processing delay due to an increase in messages is less likely to occur than in the past, it is possible to cope with an increase in nodes due to multifunctionalization of automobiles.

Hereinafter, embodiments of the relay connection unit 1 of the present invention will be described with reference to the drawings.
1 to 10 are diagrams for explaining a first embodiment of the present invention. FIG. 1 shows a configuration of an in-vehicle LAN using the relay connection unit 1 according to the first embodiment, and FIG. FIG. 3 is a block diagram showing the internal configuration of the relay connection unit 1, FIG. 4 is a diagram showing an example of a method for managing slot areas in the buffer, and FIG. 5 is an example of relay information. FIGS. 6 and 7 are diagrams showing examples of error rate information, FIG. 8 is a diagram showing the relationship between the bit error rate (hereinafter referred to as bit error rate) and the number of delay bits, and FIGS. 9 and 10 are relay connection units. 2 is a diagram illustrating an example of relay using 1; FIG.

As shown in FIG. 1, ECU2 (2A, 2B ...) is connected to the relay connection unit 1 of this invention via the communication line 3 (3A, 3B ...).
The ECU 2 includes input / output means 2a for messages ma, mb,... Conforming to the CAN standard, for example, and the communication line 3 is a twisted pair cable conforming to the CAN standard. Each of the communication lines 3A, 3B... Transmits and receives a message at a communication speed of 500 kps.
Each communication line 3 may constitute an in-vehicle LAN conforming to various standards including CAN. Moreover, the vehicle-mounted LAN based on a different standard for every communication line 3 may be comprised.

  A group of ECUs 2 (2A, 2B... 2C, 2D... 2E, 2F... 2G, 2H...) Are connected to each communication line 3 (3A, 3B, 3C, 3D), respectively. Segments Sa, Sb, Sc, and Sd (hereinafter simply referred to as segments Sa to Sd) are configured.

The relay connection unit 1 forms an in-vehicle LAN network 4 configured to be communicable with each other by relaying the message m (that is, any one of the messages ma, mb...) Between the plurality of segments Sa to Sd. Yes.
Needless to say, a single ECU 2 may be connected to each of the segments Sa to Sd to perform more reliable communication.

As shown in FIG. 2, the relay connection unit 1 is connected to a plurality of communication lines 3 (3 </ b> A to 3 </ b> D) and transmits / receives a message m, and is connected to these ports 10. A relay processing unit 11 that performs relay processing of the message m, a CPU 12 that controls the relay processing unit 11 to manage the relay processing, and a recording unit 13 in which an operation program of the CPU 12 and setting values of the relay processing unit 11 are recorded. And.
In the present embodiment, the configuration of the relay connection unit 1 is described assuming that the number of the ports 10 is 4, but the number of ports is not limited.

  The ports 10a to 10d are in-vehicle LAN communication means that enable transmission and reception of the message m according to the in-vehicle LAN communication protocol in each segment Sa to Sd formed using the communication lines 3A to 3D, respectively. Are configured to be operable. However, the ports 10a to 10d may be physically provided in one in-vehicle LAN communication means.

  The relay processing unit 11 includes a memory-embedded logic IC such as an FPGA (Field Programmable Gate Array) in which a logic circuit for relaying the message m is recorded, and a plurality of functional blocks formed by writing necessary information ( IP (Intellectual Property), and relays a plurality of messages m in parallel.

The relay processing unit 11 is configured to perform relay transmission to the relay destination port after receiving the message m being received up to the identification information and determining the relay destination port. The relay start time for starting relay transmission of the message m can be adjusted in accordance with the identification information of the message m and the port that has received the message m.
In the following description, starting transmission of a message m that is being received to a relay destination port by parallel processing is referred to as cut-and-through relay, and this message m is transmitted to the relay destination after the completion of reception of the message m. Starting relay transmission to a port is called store-and-forward relay. Further, the number of bits of the message m that must be received by the start of the relay when the cut-and-through relay is performed is referred to as a delay bit number.

  In the present embodiment, the versatility is enhanced by forming the relay processing unit 11 using the FPGA. However, the relay processing unit 11 uses a custom IC such as an application specific integrated circuit (ASIC). The functional block may be fixedly formed. Further, the port 10, the relay processing unit 11, the CPU 12, and the ROM 13 may be formed in one IC.

  The CPU 12 writes data for forming the functional block into the memory-embedded logic IC when, for example, the relay connection unit 1 is activated (or reset), thereby appropriately relaying the memory-embedded logic IC by hardware. It functions as the relay processing unit 11 that performs processing. Further, the CPU 12 monitors the communication status through the port 10 and manages the relay by the relay processing unit 11. Further, the CPU 12 may partially relay the message m by interlocking with the relay processing unit 11.

The recording means 13 is a non-volatile ROM. The ROM 13 is a functional block written in a hardware description language or the like that is read by the CPU 12 at the time of startup or the like and written into the relay processing unit 11. Is recorded as a setting value of the relay processing unit 11.
The ROM 13 records management programs P1 and P2 for causing the CPU 12 to manage the communication status of the port 10 and the relay processing unit 11. However, when the functional blocks are formed in a fixed manner at the time of manufacture, the ROM 13 does not need to record data for causing the memory-embedded logic IC to function as the relay processing unit 11.

In the relay connection unit 1 configured as described above, the CPU 12 determines the number of delay bits (the relay start time) of the message m for each reception port and identification information of each message m, and connects to each port 10a to 10d. The message m can be relayed from an appropriate relay processing start time according to the state of 3A, 3B.
In the initial state in the present embodiment, the number of delay bits is optimally adjusted in accordance with the bit error rate so that priority is given to increasing the relay speed by the cut-and-through relay.

The relay start time point at which the cut-and-through relay for optimizing the number of delay bits is performed between the start of the cut-and-through relay transmission and the completion of reception of the message m. It shows a point in time when a bit error has occurred and the probability that the message m that has started relay transmission will become an error (hereinafter referred to as an error occurrence rate) can be reduced to a predetermined value (for example, 10 ⁻⁹ ) or less.

FIG. 3 shows the configuration of the relay connection unit 1 in detail.
The relay processing unit 11 includes a buffer 20 that stores messages m received via the port 10 one by one in units of bits, and a buffer management unit 21 that manages a storage area in the buffer 20 by dividing it into a plurality of slot areas SL. Relay information recording means 22 that records the relationship between the identification information of the message m that needs to be relayed and the relay destination port as relay information Ta (described later), and relay processing of the message m stored in the buffer 20 Relay processing means 23 to be performed, and error rate recording means 24 for recording the bit error rate for each port 10a to 10d and each identification information as error rate information Tb and Tc (described later).

  The CPU 12 detects a program P0 for initial setting of the relay processing unit 11, and bit errors Ea to Ed of a message m received via the ports 10a to 10d from the states of the ports 10a to 10d, and the ports 10a. -10d and a reception error monitoring program P1 for obtaining bit error rates Ech and Eid for each identification information ID, and messages that can be transmitted using the buffer management means 21 when the ports 10a to 10d are in a transmittable state. A transmission management program P2 that realizes transmission management means for relaying m is executed.

  Note that these programs P1 and P2 are recorded in the ROM 13 readable by the CPU 12, but are executed by the CPU 12 to function as reception error monitoring means and transmission management means. These means P1 and P2 may be configured not only by software executed by the CPU 12, but also by hardware functional blocks. In this case, the reception error monitoring means and the transmission management means are connected to the relay processing unit 11. It is also possible to form in the memory embedded logic IC constituting the circuit. Therefore, in the following description, they are expressed as reception error monitoring means P1 and transmission management means P2, respectively.

  The buffer 20 is a memory configured such that a message m to be transmitted / received can be read / written in bit units, and is formed by aggregating memory cells (bit storage elements) such as flip-flops. It is a functional block configured to be able to read and write bit information simultaneously. However, even if the RAM having the number of address buses corresponding to the number of the ports 10 is formed, the RAM formed to have a plurality of address buses in a pseudo manner by time division processing, and these Any of the RAMs having the required number of address buses may be used depending on the combination.

  When receiving the message m from each port 10, the buffer management means 21 searches the slot area SL where there is a free space and uses it as a reception buffer, and records the message m being received one by one. The slot region SL in the middle is also used as a transmission buffer for the message m to be output to the relay destination port 10, and the bit information in the slot region SL is output at a speed required by each port 10a to 10d. When the received message m is received up to the identification information and recorded in the corresponding slot area SL, the identification information reception completion signal r1 is output to the relay processing means 23, and the relay destination port of the message input from the relay processing means 23 The relay channel information Ch including 10 and the relay start time is recorded in the slot area SL.

  In addition, when the received message m is stored in the empty slot area SL, the buffer management means 21 stores information indicating that this is in use for the slot area SL, and relays the message m after relay transmission. The information of the completed relay destination port is deleted, and the slot area of the message m in which the relay destination port has disappeared is released as an empty slot.

  The relay information recording means 22 is a memory configured so as to be readable at high speed, and has a bus that can be accessed at high speed with a portion storing identification information in the buffer 21.

  FIG. 4 is a view showing a management state of the slot area SL by the buffer management means 21. As shown in FIG. As shown in FIG. 4, in each slot area SL1, SL2,..., The position information Bs of the previous slot area and the position information Ns of the next slot area are recorded in addition to the message m and the relay channel information Ch. The slot areas SL in use (SL9 → SLA → SL2 →... → SLx in the example of FIG. 4) are managed so as to be connected in a chain. Also, unused slot areas SL (SL1 → SL3 → SL4 →... In the example of FIG. 4) are managed so as to be linked in a similar manner. In the slot area SL0 that manages these slot areas SL, the leading position Ts, the trailing position Ls, the leading position Fs of the empty slot area SL, and the like are recorded.

  FIG. 5 is a diagram showing an example of the relay information Ta recorded in the relay information recording means 22. As shown in FIG. 5, the relay information Ta records the relay channel information Ch in which the relay instructions Cha to Chd to the relay destination ports 10a to 10d are recorded in association with the identification information ID of each message m. . Each relay instruction Cha to Chd includes information indicating the relay start time.

  For example, in FIG. 5, a message m having an identification information ID “0001” is instructed to be relayed to the relay destination ports 10a, 10c, and 10d, and a message m having an identification information ID “0002” is the relay destination ports 10a, 10b. , 10c is instructed to “relay”. In addition, “relay after completion of reception” is set for each of the ports 10c, and it is set to always perform store-and-forward relay transmission for the port 10c. On the other hand, the relay destination ports 10a and 10d are set to perform the fastest relay, that is, the cut-and-through relay. Further, the message m with the identification information ID “0003” is set to have only the port 10c as the relay destination, and the message m with the identification information ID “0007” is set to have only the ports 10b and 10c as the relay destination. Has been.

  As shown in the present embodiment, only the identification information ID of the message m to be relayed is recorded as the relay information Ta (in the example of FIG. 5, the identification information IDs “0004” to “0006” are not recorded). Thus, the capacity of the relay information recording means 22 can be reduced, but the relay channel information Ch of all the identification information IDs may be recorded in the relay information recording means 22. In this case, it is possible to read the relay channel information Ch using the identification information ID as a direct memory address.

  The relay processing means 23 is a functional block of a logic circuit configured to be able to access the buffer 20 and the relay information recording means 23 at high speed. When receiving the identification information reception completion signal r1 from the buffer management means 21, the relay processing means 23 And a logic circuit such as a comparator for comparing the identification information of the message m in the message information and the identification information recorded in the relay information T in the relay information recording means 22. Thereby, the relay processing means 23 is configured to be able to search the identification information of the received message m from the identification information ID recorded in the relay information T at high speed and determine whether or not this is a relay target. Yes. The relay processing unit 23 is configured to determine the relay start time at the relay destination port 10 and the ports 10a to 10d using the relay information Ta and the error rate information Tb and Tc. Further, when a bit error Ea to Ed occurs in the message m being received, the relay processing means 23 immediately stops the relay processing of this message and deletes the buffer 20.

  The error rate recording unit 24 is a memory configured to record the relationship between the reception port that received the message m in which the bit error has occurred and the identification information ID, and the bit error rate, and to be readable by the relay processing unit 23.

  6 and 7 are diagrams showing examples of the error rate information Tb and Tc recorded in the error rate recording means 24. FIG.

As shown in FIG. 6, the bit error rate Eid is recorded in the error rate information Tb in association with the identification information ID of each message m. That is, the bit errors Ea to Ed monitored by the reception error monitoring means P1 are recorded together for each identification information ID. In FIG. 6, the bit error rate Eid is 10 ⁻⁹ or less for messages m having identification information IDs “0001” and “0002”. On the other hand, the bit error rate Eid is 10 ⁻⁸ for the message m with the identification information ID “0003”, and the bit error rate Eid is 10 ⁻⁷ for the message m with the identification information ID “0007”.

As shown in FIG. 7, the bit error rate Ech is recorded in the error rate information Tc in association with the reception port Ch of each message m. That is, the bit errors Ea to Ed monitored by the reception error monitoring means P1 are recorded together for each of the reception ports 10a to 10d. In FIG. 7, the bit error rate Ech is 10 ⁻⁹ or less for the message m received via the receiving ports 10a, 10c, and 10d. On the other hand, for the message m received via the port 10b, the bit error rate Ech is 10 ⁻⁸ .

  The reception error monitoring means P1 uses a redundant term such as a parity bit inserted in the message m received at each of the ports 10a to 10d, and immediately detects this when a reception error occurs to detect a bit error. In addition to outputting Ea to Ed, the bit error rates Eid and Ech are obtained and output for each identification information ID and each of the receiving ports 10a to 10d.

The bit error rates Eid and Ech recorded in the error rate information Tb and Tc are obtained by the reception error monitoring means P1 by multiplying a predetermined coefficient by reversing the time interval in which the bit errors Ea to Ed occur. It is preferable to record the average value obtained a predetermined number of times from the past. It should be noted that the bit error rate of the receiving port or identification information in which no bit error has occurred is set to the lowest value (10 ^{−9 in} this example). However, the bit error rates Eid and Ech may be obtained by averaging the occurrence frequency of the bit errors Ea to Ed within a predetermined time.

FIG. 8 shows the correspondence between the bit error rate Ech and the number of delay bits Db (relay start time). Further, when the relay start time is delayed, relay transmission is canceled due to the occurrence of a reception error of this message m. This shows the relationship of the error occurrence rate Er at which a situation occurs. In the example shown in FIG. 8, the length of the message m is set to 100 bits for simplification, and the cut-and-through relay transmission is started when the 10th bit is received in the steady state. In other words, if the bit error rates Eid and Ech at that time are 10 ⁻⁹ , when cut-through with the delay bit number 0 is performed, the remaining bit number N of the received message m becomes 90, and an error of this message m occurs. The rate Er can be obtained by the equation (2) by substituting it into the equation (1).
N × 10 ^−X = 90 × 10 ⁻⁹ = 9 × 10 ⁻⁸ ... Formula (2)

Therefore, when the relay bit is transmitted while receiving the received message m having the bit error rates Eid and Ech at the time of relaying, the delay bit number Db is the error occurrence rate of the message m expressed by the value (9) × 10 ⁻⁸ ) The number of remaining bits N can be adjusted so that it is less than or equal to 10. The error occurrence rate does not become a constant value due to quantum errors. The number of delay bits Db may be a number rounded to the minimum number of bits that can detect a bit error in the received message m.

Next, the operation of the relay connection unit 1 having the above configuration will be described with reference to FIGS.
In the example shown in FIGS. 9 and 10, the reception of the message m including the data D1 via the port 10b at the time point t0 is started.
When the port 10b receives the message m from the communication line 3B, the buffer management means 21 secures one of the empty slot areas SL and registers it as in use. That is, the position information Bs of the previous slot area and the position information Ns of the next slot area are stored so as to be added to the chain of in-use slot areas SL shown in FIG. 4, and the pieces of information Ts, Ls and Fs are adjusted as necessary.

Next, at the time t1 when the reception of the identification information ID of the received message m (“0001” in the example of FIGS. 9 and 10) is completed, the buffer management unit 21 outputs the identification information reception completion signal r1 to the relay processing unit 23. Then, the relay processing means 23 searches the identification information ID in the slot area SL and the relay information T shown in FIG. 5, and acquires the relay channel information Ch.
Further, the error rate information Tb, Tc is referred to, and the delay bit number Db is obtained using the worse one of the bit error rates Ech, Eid corresponding to the reception port 10b and the identification information ID. In this case, the bit error rate of the identification information ID is 10 ⁻⁹ or less, but since the bit error rate of the reception port 10 b is 10 ⁻⁸ , the delay bit number Db is 34 bits.

  Therefore, the relay processing means 23 waits for the delay time Δt1 from this time t1 and confirms that it can receive the reception message m for 34 bits without bit error, and then the relay channel information Ch is stored in the buffer management means 21. Output to. That is, at the relay start time t2 when the delay time Δt1 has elapsed, the buffer management means 21 can record the relay channel information Ch in the slot area SL.

On the other hand, the transmission management means P2 monitors the states of the ports 10a to 10d and outputs the transmission request signals Rsa to Rsd when they are in a transmittable state. As for the relay destination ports 10a and 10d for which "" is set, transmission is started as soon as the relay channel information Ch is recorded in the slot area SL.
As described above, the relay to the relay destination ports 10a and 10d is performed from the relay start time t2 as early as possible, and the message m being received is relayed and transmitted to the relay destination ports 10a and 10d sequentially by parallel processing (cut & cut). Through method).

  For the relay destination port 10c, the relay management means 23 sets “relay after completion of reception”. Therefore, the relay to the relay destination port 10c receives the message m to the end and receives it at the end of the message m. Only the correctly received message is relayed at time t3 when error detection is performed using the error detection code CRC. In other words, the relay to the relay destination port 10c is performed from the relay start time t2 after confirming that the message m has been correctly received (store and forward method).

  Furthermore, as shown in an enlarged view in FIG. 10, the message m received via the port 10b cannot be received correctly due to the influence of noise Nm or the like, and the data D1 included in the message m is inaccurate data D1! Consider the case where At this time, since the noise Nm is generated until the delay time Δt1 elapses in the relay processing means 23, the relay processing means 23 does not output the relay channel information Ch to the buffer management means 21, and the message m Cancel the relay. That is, inaccurate data D1! Therefore, it is possible to prevent the communication load factor in the communication lines 3A, 3C, and 3D connected to the ports 10a, 10c, and 10d from being raised unnecessarily.

  In this way, the delay bit number Db for delaying the relay start time t2 is adjusted according to the bit error rate of the reception port 10b that has received the message m, so that it matches the communication environment in each communication line 3A, 3B. Adjust as appropriate.

Similarly, at time t4 shown in FIG. 9, the message m received from the port 10d has received the identification information ID (in this example, “0002”). At time t5, the relay processing means 23 receives the relay channel information. Ch is acquired and the error rate information Tb, Tc is referred to. Here, since the bit error rates Ech and Eid corresponding to the receiving port 10d and the identification information ID are both 10 ⁻⁹ or less, there is no need for delay, and the relay channel information Ch is output to the buffer management means 21. The time point t5 can be set as the relay start time point.

  For the relay destination port 10c, the relay management means 23 sets “relay after completion of reception”. Therefore, the relay to the relay destination port 10c receives the message m to the end and receives it at the end of the message m. Only the correctly received message is relayed at time t6 when error detection is performed using the error detection code CRC. That is, the relay to the relay destination port 10c is performed from the relay start time t5 after confirming that the message m has been correctly received (store and forward method).

Further, at time t7 shown in FIG. 9, the message m received from the port 10d has received the identification information ID (“0007” in this example), and at time t8, the relay processing means 23 receives the relay channel information Ch. And the error rate information Tb, Tc is referred to. Here, the bit error rate Ech of the receiving port 10d is 10 ⁻⁹ or less, but since the bit error rate corresponding to the identification information ID of the message m is 10 ⁻⁷ , the message m is cut and through. It is not possible to relay, but it is necessary to perform store-and-forward relay.

  Therefore, for the message m having the identification information ID “0007”, the relay management means 23 confirms that all of the received message m can be received without bit errors, performs a CRC check, etc., and then determines the relay channel information Ch. The data is output to the buffer management means 21. That is, at the relay start time t9 when the delay time Δt2 has elapsed, the buffer management means 21 can record the relay channel information Ch in the slot area SL and start relay transmission.

  As described above, the delay bit number Db is adjusted in accordance with the bit error rate for each identification information ID of the message m, and thus is appropriately adjusted in accordance with the operation state of the ECU that transmits the message m.

As described above, in this embodiment, the message m is relayed by adjusting the delay bit number Db corresponding to both the bit error rate for each of the receiving ports 10a to 10d and the identification information ID of the message m. Adjustment of the starting time points t2, t5, and t9 is optimally performed.
The relay start times t2, t5, and t9 may be adjusted in accordance with either the bit error rate for each of the receiving ports 10a to 10d of the message m or the identification information ID.

In addition, the time intervals Δt1 and Δt2 for delaying the relay start time points t2, t5, and t9 are adjusted according to the bit error rates Ech and Eid at that time point, so that the message that has started relay transmission from the relay start time point Although the error occurrence rate of m can be kept low below a predetermined value (9 × 10 ^{−9 in} this example), the present invention is not limited to this point.

FIG. 11 shows a modification of FIG.
The correspondence relationship between the bit error rate Ech and the number of delay bits Db (relay start time) is shown. Further, when the relay start time is delayed, there is a situation in which relay transmission is stopped due to the reception error of this message m. This shows the relationship of the error occurrence rate Er. The delay bit number Db is set so that the delay bit number is increased by 20 bits every time the bit error rate increases by one digit, and this can cope with a case where the bit error rate fluctuates greatly.

  By using the relay connection unit 1 configured in this way, for a message m having a high error rate according to the bit error rate, a wasteful message containing inaccurate data is delayed by delaying the relay start time. It is possible to prevent m from being relayed. Therefore, the situation where the waiting time of other ECU2 which transmits / receives the message m using each communication line 3 is lengthened can be prevented.

  Since the buffer 20 has a common reception buffer and transmission buffer, even if the number of ports 10 provided in the relay connection unit 1 increases, the size of the buffer 20 can be prevented from proportionally increasing. In addition, it is possible to perform relay transmission of the message m being received by parallel processing without waste. Further, since the functional blocks constituting the buffer management means 21 manage the slot areas SL and the empty slot areas in use so as to connect the slot areas SL in a chained manner, the hardware functional blocks enable high speed operation. In addition, each slot area SL can be appropriately managed.

It is a block diagram of the vehicle-mounted LAN using the relay connection unit of this invention. It is a block diagram of the relay connection unit which concerns on 1st Embodiment. It is a block diagram which shows the structure of the said relay connection unit. It is a figure explaining the management of the buffer in the said relay connection unit. It is a figure which shows an example of relay information. It is a figure which shows the relationship between identification information and a bit error occurrence rate. It is a figure which shows the relationship between a receiving port and a bit error occurrence rate. It is a figure which shows the relationship between a bit error generation rate and the number of delay bits. It is a figure explaining the example of communication using the said relay connection unit. It is a figure which shows the detail in the example of the said communication. It is a figure which shows the relationship between the bit error generation rate which concerns on the said relay connection unit which is a modification of 1st Embodiment, and the number of delay bits. It is a figure which shows the structure of the conventional relay connection unit.

Explanation of symbols

1 relay connection unit 10 (10a, 10b...) Port 20 buffer 21 buffer management means 22 relay information recording means 23 relay processing means 24 error rate recording means P1 reception error monitoring means P2 transmission management means ID identification information T, T ′ relay information t2, t5, t9 Relay start time SL (SL1, SL2...) Slot area

Claims (5)

A plurality of ports comprising in-vehicle LAN communication means for transmitting and receiving messages; and
A buffer for sequentially storing received messages received via the port from a received part;
A relay information recording means for recording the relationship between the identification information of the message that needs to be relayed and the relay destination port;
A reception error monitoring means for detecting a bit error of a message received through the port and obtaining a bit error occurrence rate for each port or / and for each identification information;
An error rate recording unit configured to record a bit error occurrence rate for each port or / and each identification information obtained by the reception error monitoring unit;
The relay destination port corresponding to the identification information is determined in comparison with the identification information recorded in the relay information recording means at the time of receiving the identification information of the received message, and recorded in the error rate recording means The relay start time for starting the relay transmission of the received message is determined according to the bit error occurrence rate of the reception port, and stored in the buffer when the reception error monitoring means does not detect a bit error until the relay start time. Relay processing means for relaying transmitted messages;
A relay connection unit comprising:   2. The relay connection unit according to claim 1, wherein the relay processing unit stops relaying a message when the reception error monitoring unit detects a bit error before the relay start time.   The relay connection unit according to claim 1, wherein the relay processing unit stops relay transmission when a bit error occurs in a message being relayed. Buffer management means for managing the storage area in the buffer divided into a plurality of slot areas;
4. A transmission management unit that relays and transmits a message corresponding to the transmittable port using the buffer management unit when each port is in a transmittable state. The relay connection unit according to item 1.   5. The relay connection unit according to claim 1, wherein each port is connected to a vehicle-mounted electronic control unit via a communication line.

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