Utilization of the PLC as a web server for remote monitoring of the technological process

This paper presents how it is possible to utilize PLC in the task of the Web server. Described is configuration of the PLC and its connection to the computer network. Next is described principle of creation dynamic web page and described are function for process variable data read and write. User can create dynamic web page that uses combination of some programming language e.g. HTML, ASP (Active Server Pages) and Java Script. The process variables can be displayed on remote PC independently on operating system. There is only web browser needed. In the paper is also described principle of the desktop application that was programmed in the Java language. This application directly communicates with remote PLC and has own visualization of the technological process. For communication with the PLC the opened and wide HTTP web protocol is used. Described principles present some alternative for well-known technology OPC. Inscribed principles were verified in application for temperatures measurement in the underground gasification process and for system of indirect temperature measurement.