The Design Of EDC17 Series Automative Engine Disgnosis Instrument Base On OBD-?

In order to meet the increasingly stringent emission regulations and further improve the requirements of security,economy,dynamic performance,comfort and so on,a growing number of sensors used by cars,so that vehicle control system becomes more complex.When a failure occurs,determining the failure parts and reasons also become further difficult.In order to quickly find the faults of vehicle,almost all of the existing vehicle control system has increased the on-board self-diagnosis(On Board Diagnostics,OBD)system.By using the special equipments,vehicle maintenance and repair personnel can obtain the fault information stored in the electronic Control Unit(Electronic Control Unit,ECU),and quickly grasp the causes of the vehicle problems.In this paper,according to the requirement of the cooperation project "Development of EDC17 Series engine Diagnostics" with SFH Hongyan Power Assembly Co.,Ltd.,on the basis of deeply studying the related standards of automobile detection technology and network communication technology,The KWP2000 protocol based on K bus is deeply analyzed and researched.By fully considering the practical application of the system function and combining the advantages and disadvantages of the automobile engine diagnosis field,the overall system scheme is designed,and the fault diagnosis software is designed by using the object-oriented programming method to structure and modularize the program.ELM327 is used as the main control chip in automobile engine diagnosis,and PL2303 HN LM339AnTJA1040T is used as protocol control and transceiver chip.The communication hardware is designed to realize the connection between upper computer and automobile engine based on K line communication.Based on the completion of the communication hardware,the architecture design of the PC diagnostic software and the development of the system software are completed according to the requirement of the system software function.The EDC17 series automobile engine diagnosis system based on OBD-? has been tested many times in the actual vehicle test,and the system function has been optimized step by step.At present,it has been put into use in SFH Hongyan Power Plant Co.,Ltd.The obtained real-time data diagnosis is accurate and in line with the actual working conditions.The test results show that it meets the functional requirements of users and provides valuable reference value in the development of the same series of products.