Intelligent self-checking isolation method for CAN bus fault node

Abstract

The invention provides an intelligent self-checking isolation method for CAN bus fault nodes, and the method comprises the steps: arranging a CAN fault self-checking module in each CAN node except a CAN function module; a CAN function module of the CAN node is isolated from a public CAN bus through an intelligent switch 1, the CAN function module is isolated from a CAN fault self-checking module through an intelligent switch 2, and the intelligent switch 1 and the intelligent switch 2 are both controlled by the CPU control unit. Before the CAN function module of the CAN node works normally, the CPU control unit starts a fault self-checking program, turns off the intelligent switch 1, turns on the intelligent switch 2, and verifies whether the CAN function module has a fault through the CAN fault self-checking module; after verification is passed, the intelligent switch 1 is closed, the intelligent switch 2 is switched off, the CAN function module of the CAN node is connected to the public CAN bus, if verification is not passed, it is indicated that the CAN node has a fault, the intelligent switch 1 is kept in a switched-off state, and the CAN node is isolated from the public CAN bus, and therefore intelligent self-inspection and isolation of the fault node of the CAN bus are achieved under the condition that normal work of the system is not affected.

Description

Technical Field

[0001] The invention relates to the technical field of CAN bus. Background Art

[0002] CAN (Controller Area Network) bus communication is one of the most widely used field buses in the world, and is widely used in automotive electronics, industrial automation, ships, medical equipment and other fields.

[0003] There are often many nodes on the CAN bus. Although the CAN bus has the advantages of being robust and reliable, once a CAN node fails, such as a short circuit between lines or a short circuit between lines and ground on a CAN bus node, or a failure in the CAN functional element of the node, the entire CAN bus network may be paralyzed. In addition, the CANP and CANN lines of each node are connected together, making it very difficult to locate and isolate the faulty node.

[0004] At present, the commonly used CAN bus fault detection methods in the industry include: one solution is to conduct a comprehensive test on the entire CAN bus network before the system is put into operation, which requires the introduction of test equipment and the injection of test signals, increasing the complexity of the test work, and simple single-node testing is not enough to detect faults; another solution is to add an intelligent switch between each node and the public CAN bus. The intelligent switch is uniformly controlled by the host computer through a certain communication bus. This solution introduces an additional communication control bus for the intelligent switch between each CAN node, increasing the complexity of the system. Summary of the invention

[0005] In the current CAN bus application scenario, once a node fails, it may cause the paralysis of the entire CAN bus system, and it is very difficult to locate and isolate the faulty node. The currently commonly used CAN bus fault detection method usually increases the complexity of system control and affects the normal operation of the CAN bus system. In order to solve the above technical problems, the present invention provides an intelligent self-checking and isolating method for a CAN bus faulty node.

[0006] The present invention is achieved through the following technical solutions:

[0007] In addition to the CAN function module, a CAN fault self-check module is set inside each CAN node; the CAN function module of the CAN node is isolated from the public CAN bus through the intelligent switch 1, and the CAN function module is isolated from the CAN fault self-check module through the intelligent switch 2, and both the intelligent switch 1 and the intelligent switch 2 are controlled by the CPU control unit; before the CAN function module of the CAN node works normally, the CPU control unit starts the fault self-check program, disconnects the intelligent switch 1, closes the intelligent switch 2, and verifies whether the CAN function module has a fault through the CAN fault self-check module; after the verification passes, the intelligent switch 1 is closed, the intelligent switch 2 is disconnected, and the CAN function module of the CAN node is connected to the public CAN bus. If the verification fails, it indicates that the CAN node has a fault, the intelligent switch 1 remains disconnected, and the CAN node is isolated from the public CAN bus, thereby realizing the intelligent self-check and isolation of the CAN bus fault node without affecting the normal operation of the system.

[0008] Furthermore, the fault self-check program of the present invention is executed by the CPU control unit of the CAN node, and test data is sent to each other through the CAN fault self-check module and the CAN functional module to perform function verification and fault detection on the CAN functional module; and the fault self-check program is only executed before the CAN functional module works normally, and does not affect the normal operation of subsequent CAN functional modules.

[0009] Furthermore, the CAN fault self-detection module of the present invention is only used to perform fault detection on the CAN functional module of the CAN node. It is controlled by the fault self-detection program inside the CAN node and is not controlled by the external functional module of the node. It does not affect the normal operation of the external functional module of the node. The setting of the CAN fault self-detection module will not increase the mutual control path between the various CAN nodes and will not increase the complexity of system control.

[0010] Compared with the prior art, the present invention can realize accurate positioning and isolation of faulty nodes on the CAN bus, without introducing external detection equipment or injecting external test signals, without affecting the normal operation of CAN functional modules in the CAN nodes, without increasing the mutual control paths between the CAN nodes, without increasing the complexity of system control, and can realize intelligent self-checking and isolation of faulty nodes on the CAN bus. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The schematic diagram of the intelligent self-checking and isolating method for a CAN bus fault node according to an embodiment of the present invention (single node);

[0012] Figure 2 It is a principle block diagram of the intelligent self-checking and isolating method for a CAN bus fault node according to an embodiment of the present invention (multiple nodes);

[0013] Figure 3This is a schematic diagram of the principle of the intelligent switch according to an embodiment of the present invention;

[0014] Figure 4 This is a flow chart of a fault self-checking program in a CAN node according to an embodiment of the present invention;

[0015] Figure 5 The present invention is a flowchart of the intelligent self-checking and isolating method for a CAN bus fault node according to an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention is further described in detail below in conjunction with specific implementation methods.

[0017] Figure 1 and Figure 2 The present invention is a block diagram of the principle of the intelligent self-checking and isolating method for CAN bus faulty nodes according to an embodiment of the present invention. In addition to the CAN function module, a CAN fault self-checking module is set inside each CAN node; the CAN function module of the CAN node is isolated from the public CAN bus through the intelligent switch 1, and the CAN function module is isolated from the CAN fault self-checking module through the intelligent switch 2, and both the intelligent switch 1 and the intelligent switch 2 are controlled by the CPU control unit; before the CAN function module of the CAN node works normally, the CPU control unit starts the fault self-checking program, disconnects the intelligent switch 1, closes the intelligent switch 2, and verifies whether the CAN function module has a fault through the CAN fault self-checking module; after the verification is passed, the intelligent switch 1 is closed, the intelligent switch 2 is disconnected, and the CAN function module of the CAN node is connected to the public CAN bus. If the verification fails, it indicates that the CAN node has a fault, and the intelligent switch 1 remains disconnected, and the CAN node is isolated from the public CAN bus, thereby realizing the intelligent self-checking and isolation of the CAN bus faulty node without affecting the normal operation of the system.

[0018] Figure 3 The figure is a schematic diagram of the principle of the intelligent switch according to the embodiment of the present invention. The intelligent switch can select a double-pole single-throw switch for connecting and disconnecting the CAN bus, and its form can adopt a circuit design scheme of an optocoupler plus a dual-channel relay. The switch signal output by the CPU control unit controls the on-off of the primary side of the optocoupler, and the secondary side of the optocoupler is connected in series with the coil of the relay, thereby realizing the on-off control of the two contacts of the relay.

[0019] Figure 4This is a flow chart of the fault self-checking program in the CAN node described in the embodiment of the present invention. After the CPU control unit is powered on, the fault self-checking program is started, and the CAN function module and the CAN fault self-checking module are initialized respectively; first, the CAN fault self-checking module sends test data to the CAN function module, and the CAN function module verifies the data after receiving the data. After the data verification is normal, the CAN function module sends test data to the CAN fault self-checking module again, and the CAN fault self-checking module verifies the data after receiving the data. If both data verifications are normal, it means that the CAN function module of the CAN node self-checks normally, and the CAN node is connected to the public CAN bus. If one of the two data verifications is abnormal, it means that the CAN function module of the CAN node has a fault abnormality, and the CAN node is isolated from the public CAN bus.

[0020] Figure 5 The flowchart of the intelligent self-checking and isolating method of the CAN bus faulty node described in the embodiment of the present invention is shown in FIG. After the CAN bus system is powered on, all CAN nodes start the fault self-checking program in parallel to automatically determine whether there is a fault in the CAN function module inside the node. If the self-checking is normal, the node is connected to the public CAN bus. If there is a fault in the self-checking, the node is isolated from the public CAN bus. Without affecting the normal operation of the system, the entire CAN system can realize the intelligent self-checking and isolation of the CAN bus faulty node.

Claims

1. An intelligent self-checking and isolating method for a CAN bus fault node, characterized in that: In addition to the CAN function module, a CAN fault self-check module is set inside each CAN node; the CAN function module of the CAN node is isolated from the public CAN bus through the intelligent switch 1, and the CAN function module is isolated from the CAN fault self-check module through the intelligent switch 2, and both the intelligent switch 1 and the intelligent switch 2 are controlled by the CPU control unit; before the CAN function module of the CAN node works normally, the CPU control unit starts the fault self-check program, disconnects the intelligent switch 1, closes the intelligent switch 2, and verifies whether the CAN function module has a fault through the CAN fault self-check module; after the verification is passed, the intelligent switch 1 is closed, the intelligent switch 2 is disconnected, and the CAN function module of the CAN node is connected to the public CAN bus. If the verification fails, it indicates that the CAN node has a fault, and the intelligent switch 1 remains disconnected, and the CAN node is isolated from the public CAN bus, and the CAN bus fault node is intelligently self-checked and isolated without affecting the normal operation of the system.

2. The intelligent self-checking and isolating method for a CAN bus fault node according to claim 1 is characterized in that: The fault self-check program is executed by the CPU control unit of the CAN node. The CAN fault self-check module and the CAN functional module send test data to each other to perform function verification and fault detection on the CAN functional module. The fault self-check program is only executed before the CAN functional module works normally and does not affect the normal operation of subsequent CAN functional modules.

3. The intelligent self-checking and isolating method for a CAN bus fault node according to claim 1 is characterized in that: The CAN fault self-check module is only used to detect faults in the CAN functional module of the CAN node. It is controlled by the fault self-check program inside the CAN node and is not controlled by the external functional module of the node.

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