Research On Function Test System Of Vehicle Body Module Based On CAN Bus

With the current rapid development of information technology, the intelligence and networking of automotive electronic has become a trend now. Because of the reliability and openness, CAN bus has become the most extensive used data communication network. How to test the function of the CAN bus products is a problem the automotive electronic OEMs confronting. The manual test means is in common use at home, and it is lowly efficient and reliable. For solving the bottleneck that the behindhand test means induced and improving the level of the CAN bus products testing, this paper develops an automatic test system which has high automation, reliability, generability and openness.In order to clarify the needs of the test system, this paper firstly analyzes the function of the CAN bus modules and the characteristic of the SAE J1939 protocol, and then puts forwards three design solutions and fixs the final one from them by comparing. Expatiates the hardware and software overall design respectively. The design solution of the test system, which is based on the modular PLC, interface circuit including MCU and PC including communication interface cards, has high reliability and openness. To solve the connections between the PLC IO modules and the IO pins of the CAN bus modules, designs several kinds of IO interface circuits. The test system uses"virtual resistor"test means to test the analog input function and it has the advantages of easy control, high accuracy and small space occupation over the resistor arrays test means. To enhance the reliability and serviceability, this paper builds a three levels software architecture, which consists of the low level PLC control procedure, middle level CAN messages management procedure and high level HMI (human machine interface) procedure. The use of database for control logics and test results of CAN bus modules storage makes the test system function more flexible.At last, the practical running experience indicates that the automatic test system this paper designed has friendly human machine interface, convenient operation, high efficiency, accurate test results. It improves the test efficiency and quality of the CAN bus modules. The flexible configuration enhances the generability of the test system. The test system could be a reference to CAN bus products testing.