Research And Design Of C/S Mode Multi-tiers Distributed DataBase System Based On OPC

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, the upgrade and transplant of the system is inconvenient, and the real-time and security become more and more difficult as well. 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.In addition, we mostly still adopt the simple mode-Server/Client in the present control systems, however, its instability, dangerous and inferior systematic function have been perplexing us all the time, by adopting multi-layer B/S or C/S mode, it is more convenient to realize multi-user's controlling and cross-platform. Furthermore, improve the function of global system and the maintenance , upgrade become simple because of adopting multi-tier structure, meanwhile make the system more secure and humanized further.The system is composed of Communicational Mechanism of Winsock and technique of COM/DCOM, which based on OPC specification, and applies the he technique of COM/DCOM and Delphi to develop MIDAS under C/S mode, discuss the development mechanism of OPC data interface and multi-tier distribution and discuss the problems of real-time monitoring system as well. Data collection and sharing have been realized tentatively that has studied and design a whole server/client, which include displaying , stating and analyzing of data, thus lay a solid foundation for the realization of the networked, open real-time monitoring system.The paper combines a series of top grade technique such as OPC technique. COM, database technique and network technique and so on, particularly discuss the real-time supervisory and controlling system based on OPC technique. Suchfunction module as query , browsing and management of terminal end, moreover , it analyzes the benefit from OPC technique, throws light on the function, internal mechanism, interactive form and data storage; of OPC technique. With expansion and improving of OPC technique, the supervisory and controlling system will have greater progress in the future.What we have done is only elementary sludy to how to develop our real-time open supervisory and controlling technique based on web, reach some level of practicality and have certain advanced teclinique, but is expected to realize production and commodity. With the development of computer's level and standardization of product in our automation industry. We believe that we will have a dramatical progress in monitoring industry in future.