Visual PLC-programming using signal interpreted Petri nets

In this contribution, we present a graphical programming approach for Programmable Logic Controllers (PLCs) based on a special type of Petri net, the Signal Interpreted Petri Net (SIPN). We give an introduction to PLCs and an overview of the languages used to program them. From this overview, we conclude that for PLCs a language is missing that is capable of a simple graphical description of sequential and concurrent behavior. SIPN is such a language. We present the SIPN approach and some corresponding analysis methods. Furthermore, we report on some experiments done in a university course, that show that the method is indeed useful in solving control problems. Since programming a controller without tool-support is nearly impossible, we present a tool for graphical editing and compilation of SIPN. In the development of the tool, not only the implementation of the SIPN as it is defined in theory played a role, but the projected application area and user interest were also considered.