JP2008236408A - Multiplex communication apparatus for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information processor for detecting the existence of an ECU transmitting an error frame and a bus having communication abnormality and specifying an ECU connected to the bus and having abnormality in a transmission period of a message frame. <P>SOLUTION: In the multiplex communication apparatus 10 for vehicle for connecting a plurality of electronic control units 11 connected through a bus 12 for multiplex communication through a relay connection unit 20 and relaying communication of the electronic control units 11 by the relay connection unit 20, the relay connection unit 20 is provided, as a detecting means for communication abnormality, with a counter 21b for counting the number of message frames received from the electronic control unit through the bus 12 in each ID (identifier) attached to each message frame, and a counter value checking means 22b for comparing the counted number of the counter 21b with preset reference value per unit time to determine that the message frame is communication abnormality. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-vehicle multiplex communication device, and more particularly, to detect a communication abnormality when a communication abnormality occurs between electronic control units connected via a multiplex communication bus.

In recent years, the number of electrical components and electrical devices mounted on a vehicle has increased rapidly as the functions and performance of the vehicle have increased, and the wiring in the vehicle has become more complex and larger.
Therefore, in order to suppress the increase in the number of wires in the vehicle, electronic control units (ECUs) that control in-vehicle electrical components are grouped into seat and door body systems, engine and throttle power train systems, etc. For each group, ECUs belonging to the group are connected by communication lines, and a relay connection unit (gateway unit) is provided between the communication lines connected to different ECUs, and communication between the ECUs in the group is performed by the relay connection unit. An in-vehicle communication system that performs relaying is employed.
In this way, a large number of ECUs mounted on the vehicle are grouped, and in each group, a communication line connected to the ECU is connected to the relay connection unit, thereby reducing the number of wires, The communication speed between the ECUs via the relay connection unit is increased.

  In the above-described in-vehicle communication system, if any of the plurality of ECUs existing on the communication line fails and communication abnormality occurs, control of the vehicle and electrical components is hindered. Therefore, it is preferable that the ECU causing the communication abnormality and the bus to which the ECU is connected are identified at an early stage, and the countermeasure against the communication abnormality is quickly started.

Therefore, in Japanese Patent Laid-Open No. 2003-244170 (Patent Document 1), a load factor (occupancy rate) of a bus for multiplex communication is calculated, and a bus abnormality is detected when the bus load factor is higher than a predetermined value. Communication abnormality detection devices have been proposed.
The bus load factor is the proportion of the communication time of message frames communicated on the bus within a predetermined period, and the communication error detection device samples whether the message frame is transmitted on the bus and determines the communication time. The bus load factor is calculated to determine the bus communication abnormality.

  In Japanese Patent Laid-Open No. 2006-222800 (Patent Document 2), one of a plurality of ECUs connected to one bus is set as a monitoring ECU, and the monitoring ECU is connected to a bus or other ECU. There has been proposed a multiplex communication apparatus that detects a failure occurring in an ECU. An ECU other than the monitoring ECU transmits a monitoring frame to the monitoring ECU. If the monitoring ECU cannot receive a monitoring frame from a certain ECU, the monitoring ECU is connected to the ECU or a bus in the vicinity of the ECU. It is determined that a communication error has occurred.

However, in Patent Document 1, there is a problem that communication abnormality is detected on a bus to which an ECU in which communication abnormality has occurred is connected, and the ECU that has communication abnormality is not identified.
In addition, while a certain ECU transmits a large number of message frames at a transmission cycle exceeding the normal value, another ECU connected to the same multiplex communication line cannot transmit the message frame or the transmission cycle of the message frame is long. Sometimes, the bus load factor may appear to be normal. In such a case, there is a problem that the communication abnormality detection device using the bus load factor as in Patent Document 1 cannot determine the bus communication abnormality.

  Further, when the communication protocol of the in-vehicle communication system is CAN, the message frame includes an error frame transmitted by an ECU or a relay connection unit that detects a bus error in addition to a normal frame for transmitting and receiving data. That is, a bus on which an ECU or the like that transmits an error frame exists is a bus in which a communication error occurs due to transmission / reception of a message frame including a format error or the like. However, in Patent Document 1, regardless of the type of message frame, the bus load factor is calculated from the communication time of the message frame to determine the bus communication abnormality, and no error frame is described.

  Furthermore, in Patent Document 2, the location where the communication is interrupted is detected based on whether or not the monitoring ECU can receive the monitoring frame transmitted from another ECU. However, the reception of the monitoring frame is completely interrupted. However, there is a problem that a communication abnormality cannot be detected when the reception cycle is abnormal.

JP 2003-244170 A JP 2006-222800 A

  The present invention has been made in view of the above problem, and detects a bus having an abnormal communication due to the presence of an ECU that transmits an error frame, and the transmission cycle of a message frame connected to the bus is abnormal. The ECU is specified.

An in-vehicle system in which an electronic control unit connected via a bus for multiplex communication is connected via a relay connection unit, and a message frame transmitted and received between the electronic control units belonging to different buses is relayed by the relay connection unit A multiplex communication device for
A counter that counts the number of message frames received from the electronic control unit via the bus for each ID (identifier) attached to each message frame;
Counter value check means for comparing the count number of the counter with a reference value per unit time set in advance and determining that the message frame of the ID is in communication abnormality;
An in-vehicle multiplex communication device is provided.

According to a second aspect of the present invention, there is provided an on-vehicle multiplex communication apparatus in which a plurality of electronic control units are connected to each other via a multiplex communication bus, wherein one of the plurality of electronic control units is controlled electronically. As a means for detecting communication abnormalities, the unit
A counter that counts the number of message frames received from other electronic control units for each ID (identifier) attached to each message frame;
Counter value check means for comparing the count number of the counter with a reference value per unit time set in advance and determining that the message frame of the ID is in communication abnormality;
An in-vehicle multiplex communication device is provided.

According to the above configuration, one electronic control unit of the relay connection unit of the first invention or the plurality of electronic control units of the second invention is provided for each message frame transmitted by each other electronic control unit (ECU). The counter includes a counter, and counts the number of message frames per unit time received via the bus by the counter and compares it with a reference value, thereby determining communication error of the message frame and determining the message frame from the message frame ID. Can be identified.
Furthermore, by detecting a message frame having a communication error, it is possible to quickly cope with the communication error such as recording a communication error in the message frame or a predetermined fail-safe process.

  In addition, when an ECU connected to a multiplex communication line transmits a large number of message frames at a transmission cycle exceeding the normal value, another ECU cannot transmit a message frame or the transmission cycle of the message frame is long As in Patent Document 1, it is not possible to reliably determine whether the bus or the ECU is in communication abnormality only by calculating the bus load factor. However, in the in-vehicle multiplex communication device of the present invention, the relay of the first invention is performed. Since the number of each message frame transmitted to the connection unit or the electronic control unit having the communication abnormality detecting means of the second invention is counted, it is possible to determine the communication abnormality for each message frame.

The process in which the counter counts the number of message frames is periodically performed by being incorporated in the normal process of the relay connection unit of the first invention or the electronic control unit having the communication abnormality detecting means of the second invention. .
The determination of the ECU communication abnormality by the counter value check means may be performed during the idle time of the normal process. In addition, when a bus communication abnormality is detected by a bus abnormality detection unit described later, the normal process may be interrupted to give priority.

In addition, according to the first invention, the relay connection unit (gateway unit) to which the bus is connected is provided with the communication abnormality detection means. In addition, it is possible to identify an ECU having a transmission cycle communication abnormality from an ECU connected to the communication abnormality bus.
Further, according to the second invention, since one of the plurality of ECUs is provided with the communication abnormality detecting means, the transmission period communication abnormality ECU is identified from the plurality of ECUs connected to one bus. can do.

Bus abnormality detecting means for detecting an error frame from a message frame transmitted to the bus and specifying a bus with abnormal communication, and / or bus abnormality detecting means for calculating a load factor of the bus and specifying a bus with abnormal communication With
Preferably, the counter value check means determines that the message frame is in communication error from the count number of message frames received via the bus determined as communication error by the bus error detection means.

When a message frame including a format error or a bit error is transmitted to the bus, the ECU or relay connection unit that detects the message frame including the error transmits an error frame. That is, a bus on which an ECU or the like that transmits an error frame exists is a bus in which a communication error occurs due to transmission / reception of a message frame including a format error or the like. A message frame including a format error is also an error frame. Therefore, the bus abnormality detection means can detect whether or not a communication abnormality has occurred on the bus by detecting whether or not an error frame has been transmitted / received.
The bus abnormality detection means measures the time for the electronic control unit having the relay connection unit of the first invention or the communication abnormality detection means of the second invention to transmit / receive a normal frame to / from each bus, thereby measuring the bus load factor. And whether or not a communication abnormality has occurred on the bus can be detected from the bus load factor.
Further, a message frame transmitted by each ECU or relay connection unit that has received a message frame including an error, a message frame in which a format error has occurred, a message frame in which an ID cannot be identified, and the like are used as error frames. The bus load factor is calculated by measuring the time for transmitting / receiving the bus to / from each bus, and it can be detected from the bus load factor whether a communication abnormality has occurred on the bus.

When the bus abnormality detecting unit detects a communication abnormal bus, the counter value checking unit determines communication abnormality of the message frame connected to the bus. At this time, the processing of the counter value check means is preferentially performed by interrupting the normal processing, not the idle time of the normal processing.
Thus, after the bus abnormality detecting means identifies the communication abnormal bus, only the communication abnormality of the message frame transmitted by the ECU connected to the bus is preferentially determined. It can be detected early. Further, the processing of the counter value check means can be reduced as compared with the case of determining communication abnormality of all ECUs.

A reception cycle detection unit that detects a reception cycle of a message frame determined to be communication abnormality by the counter value check unit;
It is preferable to include a reception cycle check unit that compares the reception cycle detected by the reception cycle detection unit with a preset reference value to determine a communication abnormality of the electronic control unit that has transmitted the message frame.

  By detecting the reception cycle of the message frame determined to be communication abnormality by the reception cycle check means, it is possible to specify that the ECU that transmits the message frame has a transmission cycle communication abnormality. Further, when the message frame cannot be received beyond a predetermined period, it can be specified that communication is interrupted.

As described above, the in-vehicle multiplex communication device according to the first aspect of the present invention includes a communication abnormality detecting means in the relay connection unit, and the counter value check means as the detecting means is connected to another electronic control unit (ECU). A counter is provided for each message frame to be transmitted, and the number of message frames per unit time is counted and compared with a reference value to determine whether or not the transmission cycle of each message frame is abnormal, and an ECU having a communication abnormality is specified. be able to.
Further, the in-vehicle multiplex communication device of the second invention is provided with a communication abnormality detection means in one electronic control unit of the plurality of electronic control units, and the counter value check means which is the detection means includes other A counter is provided for each message frame transmitted by the electronic control unit (ECU), and the number of message frames per unit time is counted and compared with a reference value to determine whether or not the transmission cycle of each message frame is abnormal. It is possible to identify an ECU having a communication error.
Further, since the reception period check means detects the period for receiving the message frame, the ECU can specify that the transmission period is abnormal or the communication is interrupted.
Further, by detecting whether or not the bus abnormality detection means has received an error frame, it is possible to detect whether or not a communication abnormality has occurred on the bus.

Embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a first embodiment of the present invention.
FIG. 1 shows a configuration of an on-vehicle multiplex communication apparatus 10 according to the present invention. A relay connection unit 20 (gateway unit) connects multiple communication buses 12 connected to an electronic control unit (ECU) 11, and different buses 12. Relay of transmission / reception of the message frame m between the ECUs 11 connected to the ECU 11 is performed.

  In the present embodiment, two buses 12A and 12B are connected to the relay connection unit 20, and one ECU 11A and 11B are connected to each bus 12A and 12B, respectively. The communication protocol of the multiplex communication uses CAN, and the message frame m transmitted / received on the bus 12 includes a normal frame mo including data transmitted / received between the ECUs 11 and the ECU 11 or the relay connection unit 20 that detects an error. Two types of message frames m, which are error frames me to be transmitted, are provided.

The relay connection unit 20 performs the operation shown in FIG. 2 in order to identify the ECU 11 having a communication abnormality.
First, in step S10, the abnormality of the bus 12 connected to the relay connection unit 20 is detected. A bus abnormality detecting means 22a, which will be described later, detects whether a communication abnormality has occurred in each bus 12. If a communication abnormality has occurred on the bus 12, the process proceeds to step S11, and if not, step S10 is repeated.
Next, the counter value check unit 22b checks the counter value of the normal frame mo received in step S11. When the bus abnormality detection in step S10 detects the bus 12 having a communication abnormality, the number of message frames m transmitted by the ECU 11 connected to the bus 12 is counted, and the number of message frames m within the unit time is used as a reference. The abnormality of the message frame m transmitted by each ECU 11 is determined by comparing with the value.

In step S12, the reception cycle of the message frame m is determined by the reception cycle check means 22c. The reception cycle of the message frame m transmitted by the ECU 11 identified as a communication abnormality is detected. If the reception cycle is abnormal, the process returns to the start, and if it is normal, the process proceeds to step S13.
In step S13, it is determined that the message frame m is a communication interruption or a transmission cycle abnormality, and the ECU 11 that has transmitted the message frame m is identified as a communication abnormality ECU 11.

The relay connection unit 20 includes a buffer unit 21, a processing unit 22, a storage unit 23, and a transmission / reception unit 24 that transmits and receives a message frame m.
The buffer units 21A and 21B are provided for each of the buses 12A and 12B connected to the relay connection unit 20, and include a normal frame reception time measurement counter 21a-1, a normal frame transmission time measurement counter 21a-2, and an error frame reception time measurement counter. There are four time measurement counters 21a, 21a-3 and an error frame transmission time measurement counter 21a-4.

The normal frame reception time measurement counter 21a-1 and the error frame reception time measurement counter 21a-3 measure the time required for reception of the normal frame mo and the error frame me received by the relay connection unit 20 from the ECU 11. The normal frame transmission time measurement counter 21 a-2 and the error frame transmission time measurement counter 21 a-4 measure the time required for transmission of the normal frame mo and error frame me that the relay connection unit 20 transmits to the bus 12. When the relay connection unit 20 transmits / receives a plurality of message frames m per unit time, each time measurement counter 21a measures the sum of the time required for transmitting / receiving the plurality of message frames m.
These four time measurement counters 21a are used for bus abnormality detection described later.
The buffer unit 21 is provided with a counter 21b for counting the number of normal frames mo received from the ECU 11 connected to each bus 12, for each ID (identifier) of each normal frame mo. The counter 21b is used for a counter value check.

  The processing unit 22 includes a bus abnormality detection unit 22a, a counter value check unit 22b, a reception cycle check unit 22c, and a reception cycle detection unit 22d. In addition, there is provided means (not shown) for performing normal processing such as relaying of a normal frame mo transmitted and received between ECUs 11 belonging to different buses 12.

The bus abnormality detection unit 22a includes a bus load factor calculation unit 22a-1, an error frame transmission time measurement counter 21a-3, and a check unit 22a-2 for the error frame transmission time measurement counter 21a-4.
The bus abnormality detection means 22a detects the abnormality of the bus 12 by two methods. In the first method, the check means 22a-2 of the error frame time measurement counter 21a is operated by the error frame reception time measurement counter 21a-3 and the error frame reception time measurement counter 21a-3. In this method, the measurement value of the error frame transmission time measurement counter 21a-4 is read, and when the reception time or transmission time of the error frame me is measured, the bus 12 to / from which the error frame me is transmitted / received is communication abnormal.
The second method is a method in which the bus load factor calculated by the bus load factor calculating unit 22a-1 is compared with the bus load factor reference value 23a stored in the storage unit 23 to identify the bus 12 having a communication abnormality.

The counter value check unit 22b is configured to store the count value of the reception counter 21b of the normal frame mo transmitted from the ECU 11 connected to the bus 12 and the storage unit when the bus abnormality detecting unit 22a detects the communication abnormality bus 12. 23 is compared with the reference value of each normal frame mo stored in the reception number map 23b of 23, and the communication abnormality ECU 11 is specified.
The reception cycle detection unit 22d detects the reception cycle of the message frame m.
The reception cycle check unit 22c compares the reception cycle of the normal frame mo transmitted by the ECU 11 with the reference value when the communication abnormality ECU 11 is specified by the counter value check unit 22b, and the transmission cycle is abnormal. An ECU is specified.

The storage unit 23 includes a bus load factor reference value 23a, a reception number map 23b, and a reception cycle reference value 23c.
The bus load factor reference value 23a is a reference value used by the bus abnormality detecting unit 22a, and the bus abnormality detecting unit 22a compares the bus load factor with the reference value to determine a communication abnormality of the bus 12.
The reception number map 23b is a reference value used by the counter value check unit 22b, and sets a reference value based on the transmission period of the normal frame mo transmitted by each ECU 11. The counter value check means 22b compares the number of receptions per unit time of the normal frame mo with a reference value to determine the ECU 11 with communication abnormality.
The reception cycle reference value 23c is a reference value used by the reception cycle check unit 22c. When the reception cycle of the normal frame mo received by the relay connection unit 20 is longer than the reference value, the reception cycle check unit 22c of the processing unit 22 The ECU 11 transmitting the normal frame mo is identified as having a communication abnormality.

Next, the operation of the relay connection unit 20 of the present invention will be described.
The relay connection unit 20 measures the time required for transmission / reception of the normal frame mo and error frame me, and receives a normal frame reception time measurement counter 21a-1, a normal frame transmission time measurement counter 21a-2, and an error frame reception time measurement counter 21a-. 3. The measured values are stored in the four time measurement counters 21a of the error frame transmission time measurement counter 21a-4.
In addition, a count value of the number of received message frames m is stored in a counter 21b provided for each ID of the received message frame m.
The processing of the time measurement counter 21a and the counter 21b is incorporated in the normal processing of the relay connection unit 20 and periodically performed.

Next, as shown in step S10 of FIG. 2 described above, the abnormality of the bus 12 is detected by the bus abnormality detecting means 22a.
The bus abnormality detection means 22a detects the bus abnormality by two methods.
First, the first method using the error frame me will be described. The error frame me is transmitted by the ECU 11 and the relay connection unit 20 that detect the error when a bit error or a format error occurs in the normal frame mo, and the error frame me is transmitted to the bus 12. In this case, a communication abnormality has occurred on the bus 12.
For this reason, the bus abnormality detection means 22a reads the measurement values of the error frame reception time measurement counter 21a-3 and the error frame transmission time measurement counter 21a-4 by the check means of the error frame me time measurement counter 21a. If the reception time or transmission time of the error frame me is measured instead of zero, it is determined that a communication error has occurred in the bus 12 through which the error frame me has been transmitted and received.

Next, a second method for calculating the bus load factor and comparing it with a reference value will be described.
The bus load factor calculation means 22a-1 includes a normal frame reception time measurement counter 21a-1, a normal frame transmission time measurement counter 21a-2, an error frame reception time measurement counter 21a-3, and an error frame transmission time measurement counter 21a-4. The measurement values of the four time measurement counters 21a are read out.

The measurement values of the error frame reception time measurement counter 21a-3 and the error frame transmission time measurement counter 21a-4 indicate the time required for the relay connection unit 20 to transmit / receive the error frame me. For example, as shown in FIG. The sum t1 + t2 of the times t1 and t2 when the error frames me1 and me2 are received per unit time T becomes the measurement time of the error frame reception time measurement counter 21a-3, and the sum of the times t3 and t4 when the error frames me3 and me4 are transmitted. t3 + t4 is the measurement time of the error frame transmission time measurement counter 21a-4. The sum te of the measurement times of the error frame reception time measurement counter 21a-3 and the error frame transmission time measurement counter 21a-4 is t1 + t2 + t3 + t4, which is the time that the error frame me exists on the bus 12.
The bus load factor BRe of the error frame me is obtained by Expression (1).
BRe = te / T × 100 (%) (1)

  Similarly, the measurement values of the normal frame reception time measurement counter 21a-1 and the normal frame transmission time measurement counter 21a-2 indicate the time required for the relay connection unit 20 to transmit / receive the normal frame mo, as shown in FIG. In addition, the sum t5 + t6 of the times t5 and t6 when the relay connection unit 20 receives the normal frames mo1 and mo2, and the sum t7 + t8 of the times t7 and t8 when the normal frames mo3 and mo4 are transmitted are the normal frame reception time measurement counter 21a−. 1. It becomes the measurement time of the normal frame transmission time measurement counter 21a-2. The sum of the measurement times of the normal frame reception time measurement counter 21a-1 and the normal frame transmission time measurement counter 21a-2 is t5 + t6 + t7 + t8, which is the time that the normal frame mo exists on the bus 12.

The time Ta when the message frame m exists on the bus 12 is the sum te + to of the time when the error frame me and the normal frame mo exist on the bus 12, and the bus load factor BRo of the normal frame mo is obtained by equation (2). .
BRo = (Ta−te) / T × 100 (%) (2)
Further, the bus load ratio BR of the message frame m can be obtained by Expression (3).
BR = BRe + BRo (3)

The bus abnormality detection means 22a calculates the bus load factor BR of the message frame m for each bus 12 connected to the relay connection unit 20, and compares the bus load factor BR with the bus load factor reference value 23a stored in the storage unit 23. Is abnormal, it is determined that a communication abnormality has occurred in the bus 12.
Specifically, three values ABR, α, and β are stored in the storage unit 23 as the bus load factor reference value 23a, and the ABR is calculated and derived from the transmission period of the normal frame mo transmitted from each ECU 11. The normal bus load factor, α is the lower difference of the allowable bus load factor difference calculated from the normal frame mo transmission cycle abnormal value determined as communication interruption, and β is the allowable bus load factor calculated from the bus 12 load upper limit specified value. It is the upper difference of the difference. At this time, if BR does not satisfy Expression (4), it is determined that a communication abnormality has occurred in the bus 12.
-Α <BR-ABR, BR-ABR <β (4)

In the present embodiment, the bus abnormality detection means 22a performs both the first bus abnormality detection method and the second bus detection method, but only one of them may be performed.
Further, the bus abnormality detection means 22a repeatedly performs the bus abnormality detection by the first bus abnormality detection method and the second bus detection method, and when the abnormality of the bus 12 is continuously determined, the bus 12 Identifies the bus 12 in which a communication error has occurred.
As described above, the bus abnormality detection means 22a performs the first bus abnormality detection method and the second bus detection method, and when the abnormality of the bus 12 is determined by any of the methods, the counter value which is the next operation is determined. Check.

Next, the operation of the counter value check unit 22b shown in step S11 of FIG. 2 will be described.
When the bus abnormality detecting unit 22a identifies the bus 12 in which the communication abnormality has occurred, the processing unit 22 of the relay connection unit 20 interrupts the normal process and preferentially checks the counter value.
First, the counter value check unit 22b reads the count value TRx of the counter 21b provided in the buffer unit 21.
The counter 21 b is provided for each message frame m received by the relay connection unit 20 via the bus 12. In the present embodiment, as shown in FIG. 1, two message frames m of the normal frames moA-1 and moA-2 are transmitted from the ECU 11A, and two counters, a moA-1 counter and a moB-2 counter, are transmitted to the counter 21b. A counter is provided. Each counter 21b stores a count value TRx obtained by counting the number of each message frame m received by the relay connection unit 20 for each ID.

The counter value check means 22b reads the reception number map 23b from the storage unit 23 and compares it with the count value of the buffer unit 21 to determine the message frame m of communication abnormality.
Specifically, the reception number map 23b is a table showing the reference value IRx of the count value TRx of the message frame m for each message frame m. The reception number map 23b also describes the frame number count value error γ allowed for each reception period of the message frame m. At this time, the counter value check unit 22b determines whether or not the expression (4) is satisfied for each message frame m, and determines that the count value of the message frame m is abnormal when the expression (4) is satisfied.
| TRx−IRx | ≧ γ (4)

Further, the counter value check means 22b repeats the determination by the counter value check a plurality of times, and when it continues to determine the abnormality of the count value of the message frame m, there is a communication abnormality in the ECU 11 that transmits the message frame m. It is determined that it has occurred.
Note that the communication abnormality in the ECU 11 includes not only the abnormality in the ECU 11 but also the case where the message frame m cannot be transmitted normally due to a failure of a sensor or a device connected to the ECU 11.

Next, operations of the reception cycle check unit 22c and the reception cycle detection unit 22d will be described.
The reception cycle detection unit 22d detects the message frame m of the ID determined to be abnormal by the counter value check unit 22b, and detects the reception cycle Tr.
The reception cycle check unit 22 c reads the reception cycle reference value 23 c stored in the storage unit 23. The reception cycle reference value 23c has an upper limit value and a lower limit value. If the reception cycle of the message frame m is longer than the upper limit value of the reception cycle reference value 23c as compared with the reception cycle detected by the reception cycle detection means 22d. It is determined that communication is interrupted. Further, if it is shorter than the lower limit value of the reception cycle reference value 23c, it is determined that the reception cycle is abnormal.
More specifically, the reference value is set as T ± at, where T is the reception period when the message frame m is normally received and t is the allowable period difference time, and a> 2T / t. It is not preferable to determine that communication of the message frame m is interrupted when the reception cycle Tr is less than 3T, and it is determined that the message frame m is disconnected when T + at> 3T.

According to the said structure, the bus | bath 12 with which ECU11 which is transmitting the abnormal message frame m was connected can be specified by providing the bus | bath abnormality detection means 22a in the relay connection unit 20. FIG. In particular, communication abnormality of the bus 12 can be easily determined by detecting whether or not the error frame me has been received by the time measurement counter 21a.
Further, by providing the counter value check means 22b, the relay connection unit 20 can detect the message frame m having an abnormal transmission cycle. Further, by checking only the count value of the message frame m transmitted / received on the bus 12 determined to be a communication abnormality by the bus abnormality detection unit 22a, the processing of the counter value check unit 22b is reduced and the communication abnormality is performed. The ECU 11 can be quickly identified.
Furthermore, by providing the reception cycle check means 22c, it is possible to determine whether the message frame m is a communication interruption or a transmission cycle abnormality, and to identify the ECU 11 having a communication abnormality.

FIG. 4 shows a second embodiment of the present invention.
In the second embodiment, step S20 in FIG. 4 is added to the operations in steps S10 to S13 in FIG. 2 of the first embodiment.
In step S20, with respect to all message frames m received by the relay connection unit 20, the count value of the counter 21b is read by the counter value check means 22b and compared with the reference value to determine whether or not each message frame m has a communication abnormality. Judgment. Further, this determination is made during the idle time of normal processing of the relay connection unit 20.
The processing of the bus abnormality detection means 22a in step S10 is also performed in parallel with the processing of the counter value check means 22b during the idle time of the normal processing of the relay connection unit 20. If the communication abnormality of the bus 12 is detected in step S10 or the abnormality of the count value is detected in step S20, the processing unit 22 interrupts the normal process and preferentially performs the operation of the next step. The communication abnormality ECU 11 is identified early.

Even in step S11, the counter value check means 22b determines whether or not the communication error has occurred in the message frame m in the same manner as in step S20. In step S11, the relay connection unit 20 receives from the bus 12 in which the communication abnormality was detected in step S10. The determination is made only for the message frame m, but in step S20, the determination is made for all message frames m received by the relay connection unit 20.
In step S20, a determination is made based on the free time of the normal process of the processing unit 22. However, in step S11, if a communication abnormality of the bus 12 is detected in step S10, the normal process is interrupted to give priority. The point of going to is different.

According to the above configuration, a certain ECU 11 connected to the multiplex communication line transmits a large number of message frames m at a transmission cycle exceeding the normal value, while another ECU 11 cannot transmit the message frame m or transmits the message frame m. Even if the period is long, the number of each message frame m transmitted to the relay connection unit 20 is counted by the counter value check means 22b in step S20. Can be determined.
In addition, since another structure and an effect are the same as that of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

FIG. 5 shows a third embodiment of the present invention.
In the third embodiment, the monitoring ECU 20 of the present invention is connected to one bus 12 and a plurality of ECUs 11C and 11D are connected, and the monitoring ECU 20 detects the communication abnormality of the other ECUs 11. Means.
The configuration of the monitoring ECU 20 of the present invention is the same as that of the relay connection unit 20 of the first embodiment. However, since it is connected to one bus 12, the transmission / reception unit 24 and the buffer unit 21 connected to the bus 12 are one. It has become one.

The monitoring ECU 20 detects a communication abnormality of the bus 12 to which the monitoring ECU 20 is connected by the bus abnormality detection means 22a. The processing of the bus abnormality detecting means 22a is performed during the remaining time of the normal processing of the monitoring ECU 20.
When the bus abnormality detection means 22a detects a communication abnormality of the bus 12, the counter value check means 22b causes the monitoring ECU 20 to detect a message frame m having an abnormal transmission cycle from the received message frames m. The processing of the counter value check means 22b is preferentially performed by interrupting normal processing.

Further, the reception cycle check means 22c determines whether the message frame m is a communication interruption or a transmission cycle abnormality, and specifies the ECU 11 having a communication abnormality.
Even in the in-vehicle multiplex communication apparatus 10 to which the relay connection unit 20 is not connected, the ECU 11 having a communication abnormality can be identified by providing the monitoring ECU 20 with a communication abnormality detecting means.
In addition, since another structure and an effect are the same as that of 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

It is a block diagram which shows the structure of 1st Embodiment of the vehicle-mounted multiplex communication apparatus of this invention. It is a flowchart which shows operation | movement of the vehicle-mounted multiplex communication apparatus. It is explanatory drawing of bus load factor calculation. It is a flowchart which shows 2nd Embodiment. It is a block diagram which shows 3rd Embodiment.

Explanation of symbols

11 (11A-11D) ECU
12 (12A, 12B) Multiple communication bus 20 Relay connection unit, monitoring ECU
21 Buffer unit 21a Time measurement counter 21b Counter 22 Processing unit 22a Bus abnormality detection unit 22b Counter value check unit 22c Reception cycle check unit 22d Reception cycle detection unit 23 Storage unit 23a Bus load factor reference value 23b Reception number map 23c Reception cycle reference value 24 Transmitter / receiver m Message frame mo Normal frame me Error frame

Claims (4)

An in-vehicle system in which an electronic control unit connected via a bus for multiplex communication is connected via a relay connection unit, and a message frame transmitted and received between the electronic control units belonging to different buses is relayed by the relay connection unit A multiplex communication device for
A counter that counts the number of message frames received from the electronic control unit via the bus for each ID (identifier) attached to each message frame;
Counter value check means for comparing the count number of the counter with a reference value per unit time set in advance and determining that the message frame of the ID is in communication abnormality;
An in-vehicle multiplex communication device comprising: An in-vehicle multiplex communication apparatus in which a plurality of electronic control units are connected to each other via a multiplex communication bus, wherein one electronic control unit of the plurality of electronic control units serves as a communication abnormality detection means. ,
A counter that counts the number of message frames received from other electronic control units for each ID (identifier) attached to each message frame;
Counter value check means for comparing the count number of the counter with a reference value per unit time set in advance and determining that the message frame of the ID is in communication abnormality;
An in-vehicle multiplex communication device comprising: A bus abnormality detecting means for detecting an error frame from a message frame transmitted to the bus and identifying a communication abnormal bus; and / or a bus abnormality detecting means for calculating a load factor of the bus to identify a communication abnormal bus. Prepared,
The counter value check means determines that the message frame is a communication error from the count number of message frames received via the bus determined as a communication error by the bus error detection means. The in-vehicle multiplex communication apparatus according to claim 2. A reception cycle detection unit that detects a reception cycle of a message frame determined to be communication abnormality by the counter value check unit;
A reception cycle check unit that compares the reception cycle detected by the reception cycle detection unit with a preset reference value to determine a communication abnormality of the electronic control unit that transmitted the message frame;
The in-vehicle multiplex communication apparatus according to claim 1, further comprising:

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