The Research Of Communication Of Real-time Based On CAN In Motion Control System

Motion control system is mainly used in the traditional industrial field of the numericalcontrol processing, packing, robot, high-speed printing and so on, in order to meet themarket de mand of rapid development, motion control system must have high speed, highprecision and require system have open characteristics. CAN bus is a field bus that havecharacteristics of high real time and high reliability, it has improved defects of slowcommunication rate and not easy to expand in motion control system based on the traditionalfield bus.This thesis first introduced the CAN bus level classification, it corresponds to the ISO/OSI physical layer and the data link layer. But there are requirements of the industrialnetwork configuration and the interconnect products that need a standard application layer.CANopen was a fully open application layer protocol that it is working on the CAN bus Forit is applying to a CAN bus not only meet the motion control system of openness andinteropera-bility and also make the system more high real-time performance.Hardware platform established on hardware platform of motion control system,Sinamics S120based on CAN bus, finished the project configuration and configuration ofthe work and communication software compilation, realized communicate mission controlfrom the industrial PC to S120uniaxial single node. Through analysed and proved thatsystem of communication performance was good.Because of CAN bus applys to the multiple node transmission, there are the large amount of data and the network big load, it leaded to real time drop. In the situation, twoscheduling algorithm of fixed priority and first deadline priority were used to analyzecommunication performance of CAN bus system by establishing the CAN bus simulationmodel in MATLAB environment. The simulation Experimental results show, two kinds ofscheduling algorithm can be very good finish scheduling task in low load, but the earliestdeadline dynamic priority scheduling algorithm improved throughput capacity of the bus,improved the real-time performance of the system in high load. In motion control system ofcommunication based on CAN bus, it provideds a solution to a problem that ensuring the real-time more node communication.