Real-time monitoring and controlling of an Allen-Bradley SLC 500 through the Internet

Remote access to control and monitor various devices in industrial and other environments is very important and big challenge for engineers and automation institutes. The Internet technology is providing this accessibility with great benefits to the industry. One such demand is to access an Alien-Bradley SLC 500 family programmable logic controller (PLC) through the Internet using any available standard Web browser. This remote access capability provides real-time data acquisition to monitor and control devices that are connected to the inputs/outputs modules of the PLC. This paper presents a novel scheme to provide real-time accessibility to Alien Bradley PLC to control equipment without using any dedicated licensed software that runs as a tool for the Web server. Microsoft .NET programming technology has been used to implement the novel scheme. It involves two steps. The first step is to read and write data from the PLC SLC 5/03 using Visual Basic .NET (VB.NET) programming language. In the second step, the SLC 5/03 data is displayed on the Web page "monitoring and controlling" as a HTML page, using Active Server Pages .NET (ASP.NET) through the Web Services. The Web server that has been utilized in this project is the Internet information services (US 5.0) under the Microsoft Windows 2000 Server.