The Study And Design Of OPC Communication Server In Opened Supervisory System

With the progress of computer technique, network technique and communication technique, traditional design method for computer based supervisory and control system has not been suitable for the requirements of the development, and the upgrade and transplant of the system is inconvenient. The situation is changed drastically with the application of OPC(OLE for Process Control) technology. OPC provides a kind of normal data exchange mechanism for many different applications in automatic system. The software-hardware manufacturers and users may benefit from it. Because of the technical and other reasons, no mature system based on OPC technology is put into use in the monitoring field of national electrical railway. According to the actual situations and current problems in current supervisory system, the communication server based on OPC technology has been investigated and designed both in theory and practice in this thesis.Firstly this thesis discusses the technique of OPC and its new development, then proposes the design of OPC middleware based on different modes. On the basis of analyzing the current problems in traditional supervisory systems, an OPC communication server in opened electric power monitoring system has been designed. Clients in accordance with OPC standard can access the devices through OPC server. The communication server encapsulates the common communication protocols of electric power system, realizes the multi protocol server, overcomes the disadvantage of conversing inflexible in protocols of the traditional monitoring system. The OPC communication server solves the problems in traditional monitoring system, and also the communication server adoptsClient/Server structure. Besides, it meets the demand of opened supervisory system, and integrates other systems easily. OPC communication server is the hardcore of the whole opened supervisory system. Therefore, it is the bridge of connecting under-layer equipment and super control software. Also it can be considered as the middleware of the monitoring system, through which the mutual operation of different manufacturer' s equipment and different fieldbus can be realized. At the end of the thesis, the performance of the server is evaluated by means of the test of OPC communication server. Finally, the development direction of OPC communication server is pointed out.