What is the analysis of CAN message frame ID in automobiles?
2 Answers
CAN message analysis is a common method used by technicians to troubleshoot electric vehicle faults. The basic process involves preparing the necessary equipment, obtaining the communication protocol and the original message, translating it, and providing preliminary handling suggestions based on the fault symptoms. Below is relevant information: 1. Composition of the data segment: The data segment consists of 8 bytes, each corresponding to the meanings agreed upon in the communication protocol. Each byte has 2 characters, with the preceding character representing the high 4 bits and the following character representing the low 4 bits. 2. Definition of new nodes: Nodes newly added to the system require address reassignment, and parameters within each node need to be reconfigured. Nodes added based on J1939 include: the vehicle control unit, automatic transmission, DCDC, electric power steering, electric power braking, motor controller, electric air conditioning controller, and power battery management system.
I think the CAN bus used in cars is like a network for communication between multiple components, and the frame ID is like a unique identification number for each message. In a CAN system, the frame ID is an 11 or 29-bit binary code used to distinguish the source and type of different messages. For example, the ID controlling the engine might be a specific number, while another ID monitors the brakes. Parsing it means identifying the actual meaning of these IDs. Using tools like OBD scanners or software such as CANalyzer, connected to the car's interface, you can see a list of IDs and match them with a database to translate them into human-readable English, such as 'engine speed' or 'fault code.' This is particularly important because cars are becoming increasingly intelligent. By analyzing IDs, you can quickly diagnose issues—for instance, when a warning light comes on, I can analyze the ID to determine which module is faulty without having to dismantle the car or guess randomly. In my spare time, I often use free apps to simulate tests while working on cars, and accumulating experience this way can help prevent major repairs.
