JP2006222800A - Multiplex communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiplex communication system wherein a fault can be accurately located in the case of the occurrence of the fault in a network system having a plurality of nodes connected to a multiplex communication line. <P>SOLUTION: The multiplex communication system having a plurality of nodes connected to the multiplex communication line is provided. At least one of the plurality of nodes is set as a monitor node for receiving monitor frames from other nodes and is caused to locate the fault of the multiplex communication system on the basis of reception patterns of monitor frames transmitted from all of the other nodes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multiplex communication apparatus, and more particularly to a multiplex communication apparatus that includes a plurality of nodes connected to a multiplex communication line and is suitable for diagnosing a failure of a network constituted by the plurality of nodes.

Conventionally, a multiplex communication system including a plurality of nodes connected to a communication line is known (see, for example, Patent Document 1). In the system described in Patent Document 1, each node stores a predetermined determination time related to a communication cycle from another node, and cannot acquire communication data from another node even if the determination time has elapsed. In this case, it is determined that communication interruption of another node has occurred.
JP 2003-143164 A

  However, in the method used in the above-described conventional system, even if it is possible to determine the presence or absence of a communication interruption abnormality of each node as described above, the communication interruption abnormality is a node that is a data transmission destination for the determination or its It cannot be distinguished whether it is caused by a failure on the communication line near the node or a failure on the communication line near the node that is the data transmission source. For this reason, there has been a limit to performing a failure diagnosis that identifies the failure portion after any communication interruption abnormality has occurred.

  The present invention has been made in view of the above points, and when a failure occurs in a network system in which a plurality of nodes are connected to a multiplex communication line, multiplex communication capable of accurately identifying the failure location. An object is to provide an apparatus.

  The above object is a multiplex communication apparatus including a plurality of nodes connected to a multiplex communication line, and includes at least one monitoring node that receives communication data from a plurality of other nodes other than the own node. This is achieved by a multiplex communication apparatus comprising failure diagnosis means for identifying a failure location based on a reception pattern by the monitoring node of communication data respectively transmitted from other nodes.

  In this aspect, at least one monitoring node among a plurality of nodes connected to the multiple communication line receives communication data from a plurality of other nodes other than the own node. And the failure location in a multiplex communication apparatus is specified based on the reception pattern by the monitoring node of the communication data each transmitted from these other nodes. If the monitoring node has received all the communication data from a plurality of other nodes, it can be determined that no failure has occurred. On the other hand, when the monitoring node cannot receive all the communication data from a plurality of other nodes, it can be determined that a failure has occurred in the multiplex communication line in the monitoring node or in the vicinity of the monitoring node. On the other hand, if the monitoring node cannot receive communication data from some other node, there will be another node from which the communication data is received by the monitoring node, and the monitoring node etc. Therefore, it can be determined that a failure has occurred in some of the other communication nodes where the communication data is not received or in the multiple communication lines near the other nodes. Therefore, according to this aspect, when a failure occurs in a network system in which a plurality of nodes are connected to a multiplex communication line, it is possible to accurately specify the failure location.

  In this case, in the above-described multiplex communication apparatus, the failure diagnosis unit may connect the monitoring node to the multiplex communication line in the vicinity of the monitoring node or the monitoring node when the monitoring node cannot receive all communication data from the plurality of other nodes. Diagnose that a failure has occurred.

  Further, in the above-described multiplex communication apparatus, the failure diagnosis unit may be configured such that when the monitoring node cannot receive communication data from a part of the plurality of other nodes, the part of the nodes or the part of the nodes It may be determined that a failure has occurred in the multiplex communication line near the node.

  In this case, in the above-described multiplex communication apparatus, when the monitoring node cannot receive communication data from some of the plurality of other nodes, the failure diagnosing unit is connected to the multiplex communication line of the some nodes. It is also possible to distinguish between the failure of the part of the node and the failure of the multiplex communication line near the part of the node based on the position at.

  In this aspect, when communication data from some of the plurality of other nodes is not received by the monitoring node, there is another node from which the communication data is received by the monitoring node. In addition, when some nodes whose communication data is not received by the monitoring node are nodes closer to the monitoring node on the multiplex communication line than other nodes whose communication data is received by the monitoring node, some of the nodes It can be determined that there is no failure in the nearby multiplex communication line and that some of the nodes themselves have failed. Therefore, according to this aspect, it becomes possible to specify the failure location more accurately.

  In the multiplex communication apparatus described above, all of a plurality of nodes connected to the multiplex communication line may be the monitoring nodes.

  According to the present invention, when a failure occurs in a network system in which a plurality of nodes are connected to a multiplex communication line, the failure location can be accurately identified.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a multiplex communication apparatus as a network system according to an embodiment of the present invention. FIG. 2 shows a specific configuration diagram of the node 10 constituting the multiplex communication apparatus of this embodiment. The multiplex communication apparatus according to the present embodiment is a system mounted on a vehicle, for example.

  In this embodiment, the multiplex communication apparatus includes three or more (four in this embodiment) nodes 10 as shown in FIG. The node 10 is an ECU or an intelligent sensor that is an electronic control unit mainly composed of a computer provided in various control devices of the vehicle. For example, the steering angle sensor that outputs a signal corresponding to the steering angle, the vehicle A yaw rate sensor that outputs a signal corresponding to the yaw rate generated around the center of gravity axis of the engine, an engine ECU that controls the engine based on the throttle opening, the accelerator opening, the engine water temperature, the wheel speed, the yaw rate, the steering rudder angle, etc. Vehicle Stability Control (VSC) that stabilizes the turning behavior of the vehicle-ECU, transmission ECU that controls the vehicle shift position based on the shift operation position, etc. Based on the brake ECU, steering angle etc. A power steering ECU that controls the steering assist force, an air conditioner operation switch, an auto air conditioner ECU that controls the air conditioning in the vehicle based on the vehicle interior temperature, and the like.

  The plurality of nodes 10 are connected to each other via a common multiplex communication line 12 to form a network using the multiplex communication line 12. Therefore, each node 10 can transmit and receive various types of data to and from other nodes 10 via the multiplex communication line 12. The multiplex communication line 12 is a shared bus composed of a single line or twisted pair line such as a CAN (Controller Area Network), and transmits data transmitted (transmitted) from each node 10 by time division multiplexing according to a predetermined communication protocol. (Multiplex communication) is possible. Hereinafter, the four nodes 10 connected to the multiplex communication line 12 are appropriately referred to as a node A, a node B, a node C, and a node D in the order of connection from the end of the multiplex communication line 12 (left end in the figure).

  As shown in FIG. 2, each node 10 includes a CPU 20 that is a central processing unit and a bus interface 22 that is connected to the multiple communication line 12. The CPU 20 includes a RAM 24, a ROM 26, and a controller 28. The RAM 24 is an area for storing information being calculated by the CPU 20 and calculation results. The ROM 26 is an area for storing a program used by the CPU 20 and an identification ID unique to data from another node 10 that the node 10 should receive. The controller 28 has a register for storing communication data. The controller 28 collates the set identification ID with the identification ID in the communication data on the multiplex communication line 12, and when the collation matches, the received data is registered. To store.

  The CPU 20 controls the controller 28 in accordance with a program created according to a predetermined communication protocol such as CAN and stored in the ROM 26, and performs transmission / reception control of data frames via the multiple communication line 12. Specifically, the output data of the own node 10 is digitized so as to be transmitted to the other node 10 via the multiplex communication line 12, and the input data received from the other node 10 via the multiplex communication line 12 is decoded. And execute its own control. The bus interface 22 is controlled by the controller 28 and transmits data to the other node 10 and receives data transmitted to the own node 10.

  The data transmitted from each node 10 toward the multiplex communication line 12 is composed of data frames having a predetermined configuration in advance. The data frame includes, for example, a start of frame (SOF) indicating the start of the frame and a field (transmission from a plurality of nodes 10) indicating an identification ID unique to each data as a data type to distinguish from other types of data. Also indicates the priority in transmitting the data when the data collides), the data length code (DLC) indicating the length of the data, and the contents of the data itself (for example, wheel speed information and driving) A field indicating a torque control command value, a CRC field for checking a transmission error, a field for confirming that reception has been normally completed, an end-of-frame (EOF) indicating the end of the frame, It is composed of

  The network system according to the present embodiment is a system that allows each node 10 to transmit data to be transmitted to another node 10 via the multiplex communication line 12 by time division multiplexing. Each node 10 sends data to the multiplex communication line 12 at regular or irregular intervals, but can start data transmission when no other data is flowing through the multiplex communication line 12, while other data When data transmission is started simultaneously from one or more nodes, data transmission is performed according to the transmission priority order, and when data transmission from other nodes is performed, data transmission is performed after waiting for a predetermined time.

  Next, a system failure detection method performed in the multiplex communication apparatus of this embodiment will be described. FIG. 3 is a diagram for explaining the principle of the system failure detection method in this embodiment. FIG. 4 is a diagram for explaining the procedure for detecting a system failure in this embodiment. FIG. 5 shows a flowchart of an example of a control routine executed by the controller of the CPU 20 in the monitoring node provided in the multiplex communication apparatus of this embodiment.

  By the way, in this embodiment, among all the nodes 10 connected to the multiplex communication line 12, there is a node 10 that detects a system failure of the multiplex communication apparatus (hereinafter, this node 10 is referred to as a monitoring node 10a). . Note that all the nodes 10 connected to the multiplex communication line 12 may be monitoring nodes 10a, but it is sufficient that at least one monitoring node 10a exists. In the following, for convenience of explanation, only the node D is appropriately designated as the monitoring node 10a.

  Each node 10 on the multiplex communication line 12 transmits at least a monitoring node 10a (to the multiplex communication line 12) a data frame (hereinafter referred to as a monitoring frame) for receiving monitoring by a monitoring node 10a other than the node 10 itself. When all the connected nodes 10 are the monitoring nodes 10a, they are transmitted to all the nodes 10) other than the own node. The transmission of the monitoring frame from the node 10 is periodically performed at a certain time interval (for example, every 500 ms; however, the interval may be different for each node 10). There may be a plurality of types of monitoring frames transmitted by each node 10 for each transmission node, but one type is sufficient. Further, the monitoring node 10a monitors whether or not to receive a monitoring frame transmitted by each of a plurality of other nodes 10 other than the own node 10.

  Here, in the configuration in which the monitoring target node 10 whose monitoring frame is monitored by the monitoring node 10a is limited to some of the nodes 10 other than the monitoring node 10a, the failure location of the system failure It becomes difficult to specify in detail. For example, in a configuration in which the monitoring target is monitored by the node D, which is the monitoring node 10a, is only the node C that transmits the monitoring frame C as shown in FIG. When the reception of the monitoring frame C by the node C is interrupted, the reception interruption is caused by the failure of the node D itself which is the transmission destination of the monitoring frame C or the multiplex communication line 12 in the vicinity of the node D. It is impossible to distinguish whether the failure is caused by the failure of the node C itself that is the transmission source of the monitoring frame C or the multiplex communication line 12 in the vicinity of the node C.

  Therefore, in the multiplex communication apparatus of the present embodiment, such inconvenience is avoided and the failure location causing the reception interruption is specified to some extent. Specifically, in this embodiment, the monitoring target by the monitoring node 10 a is set to all the nodes 10 (plural) other than the monitoring node 10 a among all the nodes 10 connected to the multiplex communication line 12. For example, the monitoring node 10a, the node D, is programmed to monitor whether it can receive the monitoring frames of all other nodes A, B, and C, respectively. The setting of the monitoring target includes the connection order (arrangement configuration) viewed from the monitoring node 10a on the multiplex communication line 12 for each monitoring target.

  When the monitoring node 10a receives the monitoring frame for all other nodes 10 other than the own node 10 on the multiplex communication line 12, the reception pattern (the normal node and the reception of the monitoring frame received by the monitoring node 10a) The combination pattern with the reception interruption node that is not performed) varies depending on the presence or absence of a system failure and the failure location.

  Specifically, the monitoring node 10a (node D) has actually received all the monitoring frames for all other nodes 10 (nodes A, B, C) other than the own node 10 on the multiplex communication line 12. In this case, it can be determined that no failure has occurred. On the other hand, when all the monitoring frames cannot be received as shown in FIG. 3B, the monitoring node 10a itself (particularly, the bus interface 22) or the multiplex communication line 12 near the monitoring node 10a (particularly, It can be determined that a failure has occurred between the monitoring node 10a and the node 10 adjacent to the monitoring node 10a on the multiplex communication line 12.

  On the other hand, as shown in FIG. 3C, when the monitoring frames for some of the other nodes 10 (node C) among the monitoring frames cannot be received at present, the monitoring frame is monitored by the monitoring node 10a ( Since the node 10 (nodes A and B) to be received exists at the node D), there is no failure in the monitoring node 10a and the multiplex communication line 12 in the vicinity thereof, and the monitoring frame is received. It can be determined that a failure has occurred in some of the nodes 10 that are not performed (node C) or in the multiple communication lines in the vicinity of the some nodes 10.

  Further, as shown in FIG. 3C, the monitoring frame of the node 10 (node C) connected at a position closer to the monitoring node 10a on the multiplex communication line 12 is not received by the monitoring node 10a. In the case where the monitoring node 10a receives the monitoring frame of the node 10 (nodes A and B) connected at a position farther from the monitoring node 10a, there is no failure on any of the multiple communication lines 12. Therefore, it can be determined that a failure has occurred in some of the nodes 10 that do not receive the monitoring frame.

  In view of the relationship between such a failure location and the reception pattern of each node 10, in this embodiment, the monitoring node 10 a stores information on all other nodes 10 other than the own node 10 connected to the multiplex communication line 12. It is stored in correspondence with the identification ID of the monitoring frame periodically transmitted, and the presence or absence of reception of the monitoring frame from all the other nodes 10 is monitored (step 100). This monitoring is realized by continuously waiting for a normal monitoring frame from each node 10 to be received for a period corresponding to the longest transmission interval of the monitoring frames of each node. You can do that. This is an abnormal frame that is not a normal monitoring frame for the multiplex communication line 12 depending on the failure location of the node 10 (which is sent ignoring the bus use state of the multiplex communication line 12, This is because a frame in which bit loss that does not conform to a predetermined communication protocol occurs may be transmitted in a random manner.

  The monitoring node 10a receives all the monitoring frames from all the other nodes 10 based on the reception pattern based on the monitoring result, and determines that no reception interruption has occurred (affirmative determination in step 102). ), It is determined that a normal state in which no system failure has occurred in the multiplex communication apparatus is secured (step 104).

  On the other hand, when it is not determined that all the monitoring frames from all the other nodes 10 have been received, that is, when it is determined that a reception interruption has occurred in any of the frames (when negative determination is made in step 102), the reception pattern If it is determined that the reception interruption is not for all of the other nodes 10 but for all of them (at the time of negative determination in step 106), monitoring is performed. A failure occurs in the node 10a itself, or a failure occurs in the multiplex communication line 12 near the monitoring node 10a (particularly, between the monitoring node 10a and the node 10 adjacent to the monitoring node 10a on the multiplex communication line 12). (Step 108). When such a failure determination is made, the fact that a failure relating to the own monitoring node 10 has occurred is stored in the memory of the own node 10 as failure diagnosis data.

  In addition, when it is determined that a reception interruption has occurred in any of the cases (when a negative determination is made in step 102), the reception interruption is a part of all the other nodes 10 based on the reception pattern. When it is determined that it is limited (when an affirmative determination is made in step 106), a failure has occurred in a part of the other node 10 itself or in a part of the multiplex communication line 12 near the other node 10 (Step 110). When such a failure determination is made, failure diagnosis data indicates that a failure related to some of the nodes 10 for which the monitoring frame is not received by the monitoring node 10a among all the nodes 10 on the multiplex communication line 12 has occurred. Is stored in the memory of the own node 10 (monitoring node 10a).

  For example, as shown in FIG. 4A, the node D, which is the monitoring node 10a, receives the monitoring frames from the nodes B and C, respectively, while the farthest node A from the monitoring node 10a on the multiplex communication line 12. When it is determined that the reception interruption for only the node A has not occurred (when an affirmative determination is made in step 112), the node A itself or the node A and the multiplex communication line 12 are not received. Above, it is determined that a failure has occurred in the multiplex communication line 12 between the node A and the adjacent node B on the front side (side closer to the node D). In this case, the node D stores in the memory of the node 10 as failure diagnosis data that a failure related to the node A has occurred.

  Further, as shown in FIG. 4B, the node D which is the monitoring node 10a receives the monitoring frames from the nodes A and C respectively, but does not receive the monitoring frame from the node B, and the multiple communication line. 12, when it is determined that reception interruption has occurred only for the node B that is halfway (at the time of negative determination in step 112), the node B itself or the node B on the node B and the multiplex communication line 12. It is also possible to determine that a failure has occurred in the multiplex communication line 12 between the adjacent node C on the near side (side closer to the node D), but in this case, the multiplex communication line 12 Since there is no reception interruption for node A far from node D as compared to node B where reception interruption occurs, a failure occurs in multiplex communication line 12 because an affirmative determination is made in step 114. And it can not be determined that determines a failure in the node B itself has occurred (step 116). In this case, the node D stores a failure related to the node B, particularly that a failure has occurred in the node B itself, in the memory of the node 10 as failure diagnosis data.

  On the other hand, the node D, which is the monitoring node 10a, receives the monitoring frame from the node C, while the monitoring frame from the node B and the farther side than the node B on the multiplexed communication line 12 (the side farther from the node D). ) Of all nodes 10 (here, only node A) are not received together, and reception is interrupted for node B and all nodes 10 farther than node B (here, only node A). Is determined (when a negative determination is made in step 114), the monitoring frame 10a is not received by the monitoring node 10a on the multiplex communication line 12 and the closest node B to that node B It is determined that a failure has occurred in the multiplex communication line 12 with the adjacent node C (step 118). In this case, the node D stores a failure related to the node B, particularly that a failure has occurred in the multiplex communication line 12 near the node B, in the memory of the node 10 as failure diagnosis data.

  As described above, in the configuration of the present embodiment, the monitoring node 10a monitors whether or not the monitoring frame transmitted from each of the plurality of nodes 10 other than the own node 10 connected to the multiplex communication line 12 is received. Then, the failure location of the system failure in the multiplex communication apparatus is specified based on the reception pattern based on the monitoring result. There is a correlation between the reception pattern of the monitoring frames from all the plurality of nodes 10 on the multiplex communication line 12 received by the monitoring node 10a, the presence / absence of the occurrence of a failure, and the currently occurring failure location. Therefore, according to the multiplex communication apparatus of the present embodiment, when a failure occurs in a network system in which a plurality of nodes 10 are connected to the multiplex communication line 12, it is possible to specify the failure location to some extent accurately. Yes.

  In the configuration of the present embodiment, if the monitoring frame from some of the nodes 10 other than the monitoring node 10a on the multiplex communication line 12 is not received by the monitoring node 10a, the monitoring is performed. The position viewed from the monitoring node 10a on the multiplex communication line 12 of a part of the nodes 10 where the monitoring frame 10a is not received by the monitoring node 10a (more specifically, the position far from the monitoring node 10a than the part of the nodes 10) Depending on whether or not there is a node 10 on which the monitoring frame is received by the monitoring node 10a), the failure of the part of the node 10 itself and the multiplexing of the part of the node 10 (near side) A failure of the communication line 12 can be distinguished. If there is a node 10 that receives the monitoring frame farther from the monitoring node 10a than some of the nodes 10 that do not receive the monitoring frame, the multiplex communication line 12 has not failed. It can be determined that a failure has occurred in the node 10 itself. It should be noted that the same processing is possible even if there are a plurality of nodes 10 (including when adjacent to each other) on the multiplex communication line 12 where some of the nodes 10 for which the monitoring frame is not received by the monitoring node 10a exist. Therefore, according to the multiplex communication apparatus of this embodiment, when a failure occurs in a network system in which a plurality of nodes 10 are connected to the multiplex communication line 12, it is possible to accurately identify the failure location. .

  In this embodiment, when the monitoring node 10a identifies a failure location, the information is stored in the memory of the monitoring node 10a. In this regard, according to the system of the present embodiment, when a failure diagnosis of a multiplex communication device is performed, the failure of the component of the multiplex communication device is determined based on information stored in the memory of the monitoring node 10a. It is possible to extract the information of the location that has occurred to some extent accurately, thereby making it possible to accurately diagnose the failure, and to prevent the normal node 10 and the multiple communication line 12 from being erroneously replaced. It becomes possible.

  Further, in this embodiment, in order to detect a system failure of the multiplex communication apparatus, the monitoring frames transmitted from all the nodes 10 other than the own node 10 on the multiplex communication line 12 are received by the monitoring node 10a. Reception monitoring is performed to monitor whether or not. In such a configuration, it is not necessary to perform transmission monitoring for monitoring whether or not the transmission of the data frame to each node 10 from the self to the multiplex communication line 12 is normally performed. Therefore, according to the system of the present embodiment, it is possible to reduce the cost and simplify the system in detecting a system failure of the multiplex communication apparatus, compared to a system equipped with an expensive transmission monitoring function. ing.

  It is assumed that all of the plurality of nodes 10 connected to the multiplex communication line 12 are monitoring nodes 10a, and that each of these nodes 10 transmits a monitoring frame to all nodes 10 other than the own node 10. The failure diagnosis data viewed from the own monitoring node 10 is stored in the memory of each monitoring node. Therefore, if such a configuration is adopted, when failure diagnosis of the multiplex communication apparatus is performed, the information stored in the memory of each monitoring node 10a is integrated, thereby constituting the components of the multiplex communication apparatus. Therefore, it is possible to extract the information of the location where the failure has occurred more accurately.

  By the way, in the above embodiment, the CPU 20 of the monitoring node 10a executes the processing of steps 102 to 118 in the routine shown in FIG.

  In the above embodiment, the multiplex communication line 12 is terminated as shown in FIG. 1 and the like. However, the present invention is not limited to this and may be a closed loop. . Further, since each node 10 is connected to the multiplex communication line 12 via a branch line, the failure of the node 10 includes a failure such as disconnection of a branch line in addition to a failure of the node 10 itself.

  In the above embodiment, the network system is configured such that various electronic control devices of the vehicle are connected to each other as the node 10 via the multiple communication line 12. However, the present invention is not limited to this. Instead, it may be mounted outside the vehicle and connected to the node 10 that is an electronic control device via the multiplex communication line 12.

It is a block diagram of the multiplex communication apparatus as a network system which is one Example of this invention. It is a concrete block diagram of the node which comprises the multiplex communication apparatus of a present Example. It is a figure for demonstrating the principle of the system failure detection method in a present Example. It is a figure for demonstrating the detection procedure of the system failure in a present Example. It is a flowchart of an example of the control routine performed in the monitoring node with which the multiplex communication apparatus of a present Example is provided.

Explanation of symbols

10 node 10a monitoring node 12 multiplex communication line 20 CPU
28 controller

Claims (5)

A multiplex communication apparatus comprising a plurality of nodes connected to a multiplex communication line,
At least one monitoring node that receives communication data from a plurality of other nodes other than its own node is provided,
A multiplex communication apparatus comprising failure diagnosis means for identifying a failure location based on a reception pattern by the monitoring node of communication data transmitted from each of the plurality of other nodes.   When the monitoring node cannot receive all the communication data from the plurality of other nodes, the failure diagnosis means diagnoses that a failure has occurred in the monitoring node or the multiple communication line in the vicinity of the monitoring node. The multiplex communication apparatus according to claim 1, wherein:   If the monitoring node is unable to receive communication data from some of the plurality of other nodes, the failure diagnosis means may cause a failure in the multiple communication lines near the some nodes or some of the nodes. 2. The multiplex communication apparatus according to claim 1, wherein the multiplex communication apparatus is diagnosed as having occurred.   When the monitoring node is unable to receive communication data from some of the plurality of other nodes, the failure diagnosing means is configured based on the position of the some nodes on the multiple communication line. 3. The multiplex communication apparatus according to claim 2, wherein a failure of the node is distinguished from a failure of the multiplex communication line in the vicinity of the part of the nodes.   5. The multiplex communication apparatus according to claim 1, wherein all of a plurality of nodes connected to the multiplex communication line are the monitoring nodes.

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