Some Research On Distributed Control System Based On CANopen Protocol

The research of network technology based on the fieldbus has become a hotspot in Automatic control area.In all kinds of the industrial fieldbus,CAN bus has been used in a lot of application fields, because of its lower cost,faster speed,higher real-time and reliability. CIA(CAN in Automation)established the higher layer protocol CANopen.The CANopen Protocol defined application layer and communication sub-protocol. The fieldbus can be widely used in the distributed control system by CANopen Protocol.First of all, the thesis investigates the status and developing prospect of filedbus technology in China and Abroad. For the purpose of improving operating efficiency of CAN bus, enhancing real-time and data-handling capacity, the thesis analyses CANopen's functions of the master and slave node and explains the design of CANopen's functions.Then, CANopen protocol will be applied to distributed control system.The thesis elaborates the realization process of CANopen Protocol base on the DSP module as well as PIC18 module. CANopen protocol of slave node is completed in PIC18 module.The slave node has the capacity of digital,analog input and output measurement. CANopen protocol of master node is completed in DSP module. The master node can change state and parameter of slave nodes by keyboard. The LCD can display the control value and real-time state of slave nodes. PC can monitor CAN-bus transmitted data stream on-line. The hardware and sofware design of two types of nodes are written in detail by this paper.This paper also gives some circuit diagram and software flow chart.Finally, two distributed control systems are designed based on CANopen protocol.One is a temperature monitoring system that is composed of a master node and two slave nodes. Another is a DC motor control system that is composed of a master node and a slave node.Through communication test, the CANopen's real-time and stability is acquired by this system.The CAN bus application of domestic is usually made by hardware rather than by upper software protocol in China.The research on this system will be raised to application level of distributed control system based on CAN-bus.