Controlling a Traffic Signal Unit

Let us now start to write a small example program. It is for a simple traffic signal unit which is supposed to control two traffic signals at an intersection. The red/green phases of both traffic signals alternate and, in order to avoid accidents, we will insert yellow or yellow/red transitional phases. The latter will be longer than the former.

In this example you will see how time dependent programs can be shown with the language resources of the IEC1131-3 standard, how one can edit the different languages of the standard with the help of CoDeSys, and how one can easily connect them while becoming familiar with the Simulation of CoDeSys.