Study And Realization Of Distributed SCADA System Based On GPRS Virtual Field Bus

SCADA system, or Supervisory Control And Data Acquisition System, may be used in many fields, such as gas, heat, electric, water supply, petroleum, chemical industry etc. As the social requirements towards these public affairs are getting higher and higher, SCADA systems are developing rapidly to ensure the automatics and modernization of their production process and schedule management. Nowadays, SCADA systems, which are always closely related to the computer technology since they were born, have experienced several generations. Distributed SCADA systems are a new generation of SCADA systems, which come from the advanced thoughts of the Contemporary Integrated Manufacturing System. Distribution means that the functions of the system are distributed, and these functions are designed according to the division of production, performance and management. This kind of systems are oriented to the requirements of schedule automatics in enterprises, in which all stations realize the production control and schedule management together through cooperation. Distributed SCADA systems are closed related to Field Bus, on which are equipments of the system based to build a network, and cause the acquisition and control of systems to extend the manufacturing scene. The use of Field Bus technology not only increases the communication ability and stability of SCADA systems, but decreases the cost of wiring and hardware during system setup, and makes it easier to carry out system management and maintenance. Stations of a SCADA system are usually distributed in different positions along city pipe networks, and the remote communication platform is not only the basement of information exchange, but also the communication carrier of Field Bus. In recent years, with the rapid development of CMCC GPRS technology, it is increasingly replacing the traditional communication, such as wireless radio, lease line and so on, by its advantages of good service and low cost, and it will take a central role in communication areas of SCADA systems. Now GPRS technology, in combination with Field Bus technology, has been the development direction of distributed SCADA systems, and this kind of GPRS Virtual Field Bus, which uses GPRS remote communication as its Bus cable and communication carrier, is being promoted widely in distributed SCADA system areas.Our study mainly aims at the construing of core protocol, the design, the realization as well as the research and the analysis of communication mechanism that guarantees proper operation of this kind of systems, and provides the integration method and design framework of distributed SCADA systems based on the GPRS Virtual Field Bus technology. In this framework, this paper proposed a data communication model based on the software-reuse objected design pattern, and appraised its performance through actual applications.This paper firstly analyzes the main characteristics of GPRS communication and Filed Bus, and establishes a model of GPRS communication platform based on which the Filed Bus protocol communication; with this foundation, we designed and implements a service platform on which functions blocks runs for the purpose of fast and efficient development of function blocks under embedded environment, introduced the characteristics and development flow the platform in detail, and analyzed the advantages of the service platform in simplifying developing procedure and resource usage. Finally, a distributed SCADA system scheme based on the GPRS Virtual Filed Bus technology is proposed, and its performances is tested through actual applications.