The Development Of CAN Simulation Platform Based On J1939 Protocol And Its Application In Diesel Vehicle SCR System

Along with the application of CAN bus technology in the vehicles, the communication system become more and more complex. So, it is important to use virtual hardware instead of the actual hardware to complete the simulation test. In this paper, the CAN bus simulation common platform based on the SAE J1939 protocol is developed. The development tool is Visual Studio Microsoft 2010 and the development language is VB.NET. Besides,In order to facilitate the software development of DCU in SCR system, and verify the performance of the DCU timely, the diesel vehicle SCR system CAN simulation platform has been developed based on SAE J1939 protocol.The paper’s major tasks are as bellows:1. The CAN bus assistant tools are designed. According to the provisions of the CAN network parameters in the J1939 protocol, the special calculators and analyzers are designed, mainly includes: identifier calculator and analyzer, extension frame filter mask calculator, baud rate calculator and analyzer. Users can determine the CAN network parameters according to actual need expediently.2. The resources storage system is designed. In this paper, the CAN bus simulation resources storage system is designed based on SQL Server, used to store the CAN message characteristic parameters and the signal characteristic parameters. At the same time, the functions of database operations are designed, mainly includes: all queries, conditions query, insert records, delete records and data updates.3. The resource editor system is designed. It includes the CAN initialize resource editor and the CAN network environment resource editor. The CAN initialize resource editor system is designed based on the USB turn CAN module. It is used to configure the hardware parameters and CAN network initialization parameters. And the CAN network environment resource editor system is designed, mainly includes: create nodes, create messages and create signals, signal value assignment.4. The communication function simulation system is designed. Mainly includes the message processing module, message sending module and message receiving module. Message processing module classifies and prioritises the messages, and then putting all the data that will be sent storage into the data send buffer in bus message data pool. Messages will be sent through message sending module. Message receiving module receives all the messages that pass validation in the CAN network real-time, and storages messages into the data receive buffer in bus message data pool for further processing.5. The analysis and diagnosis system is designed. This system analyses the received message real-time, obtains the current state value of all signals in a message, and monitors the qualities of the signals, the fault information are saved when the signals value are beyond the range. In order to prevent occasional failure, the fault management module that is used to confirm the fault finally is designed.6. The diesel vehicle SCR system CAN simulation platform is designed. Mainly includes the metering pump debugging module, metering pump information feedback module, engine monitoring module, OBD simulation control module, SCR system environment monitoring module, virtual DCU module, DTC detection module.7. The semi-physical simulation platform has been set up to verify the function of the CAN simulation common platform. Mainly includes the function of reveiving all message parameters real-time, real-time control, real-time message parsing and the fault analysis; At the same time, the correctness of the diesel vehicle SCR system CAN simulation platform has been verified.The results show that the CAN simulation common platform’s response speed is fast, software function is perfect, and operation is stable and reliable. The design of diesel vehicle SCR system CAN simulation platform is reasonable, meet the development demand of SCR system.