The Study And Designment Of Data Access Middleware Based On OPC Specification

In the current field of industrial automation that with the development of complexity,diversity and variability of the user environment,there have been the distributed control system.In this system,each subsystem has different communication system and protocol,and there is a lack of common communication interface among them.To access and manage data between the subsystems and the management systems seem to be difficult.As a fruitful resolution to satisfy the need of control systems integration,OPC technology has been proposed.By the inspiration of OPC technology and the consideration of the development direction of industrial control systems to distributed systems,a reasonable data access middleware resolution is proposed to meet the requirement of future distributed control systems from the aspect of middleware.According to the characteristics of industrial control systems and the requirements analysis of data access middleware,a three-layer C/M/S architecture is proposed and its corresponding system model is also developed. The solution of data access middleware takes the advantage of object-oriented modeling technology and achieves the function of accessing data sources transparently in the distributed control systems.