The Research And Development Of Computer Control System Based On OPC Data Access Specification

As a key technology for constructing open control system, OPC(OLE for Process Control) has become the spotlight in the industry control field. On the basis of analysing traditional control system structure, an open computer control system has been developed. The well robustness of the system has been validated through test and field application.The paper is consisted of five chapters. The first chapter is written to introduce the development of computer control system, the project background and the main tasks of this paper. Through the comparison of the tradional control system structure and the system applying OPC, the second chapter describes the the meaning of OPC, which is like a kind of "software bus", and presents that the control devices manufacturer should provide the hardware driver and OPC Server together in order to solve the problem of interoperation. Moreover, a key OPC Server has been analysed and fuctionally designed using OO thinking. UML is used to statically and dynamically describe the structure and the functions of the server. The following task is to fuctionally design the related user interface and device driver module. The third charpter describes the code realization of the OPC Server which includes the coding tips, development procedure and dynamic loading of device drivers. Some questions including OPC threading model, CPU and RAM useage, the relation between OPC and firewalls is also discussed in this chapter.The fourth chapter presents concrete application example. The OPC Server is accessed successfully by WinCC of Siemens and iFix of Intellution(belongs to GE Funuc) and applied in the FuShun Steel Factory's material blend control system. These works prove the robustness of the system based on our OPC Server. The last part prospects the future of the control system using OPC technologe and works out the following tasks.