“TRAFFICSIGNAL” declaration

Let us now turn to the POU TRAFFICSIGNAL. In the declaration editor you declare as input variable (between the keywords VAR_INPUT and END_VAR) a variable named STATUS of the type INT. STATUS will have four possible conditions, that is one for the TRAFFICSIGNAL phases green, yellow, yellow/red andred.

Correspondingly our TRAFFICSIGNAL has three outputs, that is RED, YELLOW and GREEN. You should declare these three variables. Then the declaration part of our Function Block TRAFFICSIGNAL will look like this: