The Realization Of CANopen Protocol Based On The Model Of Automobile Bus

With the development of the automotive technology, the electronic devices of automobile increase rapidly, which brings the problem that it is necessary for integrated control systems to exchange the vast signals in the real-time. The traditional wiring hameses can not satisfy the development of the quest, so more and more automobile use CAN.However, CAN-bus just define CAN physical layer and CAN data link layer of OSI communication model. Common users have to deal with the data link layer with the result that CAN chips cannot meet the requirement of configuration and product interlinkage in complicated control networks. As a completely open higher layer protocol of CAN-bus, the CANopen protocol allows different CAN devices to communicate with each other in a standardized manner and makes them interoperable. With its perfection increasingly, the CANopen protocol has been widely applied into some fields.This article firstly introduced the layers structure and each layer function of CAN-bus's network model and designed the automobile control system model based on CAN-bus. The model divided into four nodes, including EMS, ABS, SRS and body control system. Through using 16-bit freescale MCU embedded CAN controller as master chip in each node, it achieved the design of hardware circuit, so realized CAN physical layer and CAN data link layer. It also designed and finished the CAN driver layer, laying the foundation for the CANopen communication among the nodes.Secondly this article analyzed the CANopen application layer protocol in detail. It explained the core of CANopen—object dictionary, all kinds of communication objects, the allocation of COB-ID and some device profiles. Then it realized CANopen communication among the nodes in the model through software, and finished the bus data communication, network management, as well as its corresponding mission in control.