An internet based SCADA system

Abstract

The Supervisory Control and Data Acquisition (SCADA) system has an integral role in modern industry. It provides a link to the electronic controllers used to control factory plant and processes, and is the visible portion of a factory’s Human Machine Interface (HMI) system. It allows a factory operator to control the plant and provides feedback about the current state of the factory processes, including any alarms. The SCADA system also provides a way for important plant performance information to be obtained for use by managers and engineers at a corporate level. Timely access to this information is important in decision making. With large modern companies being so geographically diverse in the location of individual business units, the Internet has become an important communication channel to allow the exchange of data. This dissertation describes the design of an Internet based SCADA system that allows real-time factory data to be made available to the necessary personnel, regardless of where they may be on the globe. The system developed is based around an XML Web Service written in Visual Basic .NET. The Web Service accepts client requests and retrieves the desired information from the control database. This information is then returned to the client. XML was chosen because its simple text-based structure means that it is an easily parsed platform-independent data structure. The sample client program is a simple Windows Console application also written in Visual Basic .NET.