Research Of Industrial Fieldbus Data Access Technology Based On OPC XML-DA

With the industrial fieldbus system's technology continuously improved and the expanding of applications, the demand of system integration features of the user is increasing, the application is moving to the integrated direction based on the Web, the Internet and Intranet. In order to meet the need of the industrial field data for cross-platform, OPC Foundation made and released OPC XML-DA technical specifications which based web services technology, provides ways of vertical integration from the fieldbus control system to the enterprise information management system. Visual Studio.NET is Microsoft's next-generation development platform, you can run VB, C#, C++, J# and other languages, can develop multiple types of applications and support the development of Web Services applications, is to be the Platform of first choice of development remote data access system.This paper briefly introduces the status and trends of the fieldbus system, outlines the basis technology that OPC DA and OPC XML-DA specification based web services technology for building a data access platform. The overall framework of the data access system is given, and the choice of software programming platform is given, this paper detailed describes the development steps of local data access platform and gives the test results. This paper focuses on design of middleware server for building a remote data access platform, detailed describes steps to develop middleware server from three aspects that design of the middleware framework, programming of the data access module, developing XML Web Service module. Middleware server will upgrade OPC DA standard equipment to OPC XML-DA server equipment. The comparison C/S model with B/S model shows that remote data access based web services using C/S model, and describes the OPC XML-DA client in the form of diversification, gives specific steps that different types of OPC XML-DA client using programming. An experimental platform based DeviceNet fieldbus was built, realizes OPC XML-DA client access the field data through middleware server.