Research Of Real-time Control On Industry Control Network Based On CAN Bus

With the development of industrial control system,an increasing number of industrial control systems have the requirement of higher real-time characteristic,such as the quicker transfer of information,quicker control of filed devices,quicker display and operation of supervisor.As the representative of industrial control system network, fieldbus has became the important technology in the new generation of industrial control systems.In the area of fieldbus control system,CAN bus used a lot of new technology and a unique design,it's reliability,real-time capability and flexibility are outstanding compare to the general bus,and was recognized as one of the most promising fieldbus.Focusing on the real time capability of CAN bus,the theory of the real-time capability of CAN bus is analyzed,followed by the improvement of the real-time capability in theory.First,after the analysis of CAN bus's characteristics and main disadvantage,a conclusion that with high load the network time delay would greatly augment.Second,according to the CAN data link layer characteristic,a new schedule algorithm of time division based on dynamic PRI promote is presented.And a guarantee that the low PRI information still occupies a certain bandwidth under the condition of high load.At last,the design of a network control experiment is designed,and with the test data,a conclusion can be get that the real-time dynamic assign of PRI promote CAN bus less network delay compared to the base CAN.The study in this thesis indicates that the real-time capability based on real-time dynamic assign of PRI CAN is improved compared to the base CAN.