Yaskawa MotionWorks IEC Question

[JerryH]

I'm self teaching myself Yaskawa's IEC MotionWorks to make some changes to an existing machine we have. The original programming was done by an outside contractor which we no longer have contact with. It's going OK, figuring the most of it out so far but I've run into something I just can't get a handle on. In each POU he creates a Bool variable called "gEno" and uses it in many places. Take a look at the "gEno Example" and help me understand the purpose of this programming practice.

Thanks,
Jerry

 

[aiki202]

Not an expert..but...it looks like it is a global variable that allows the next step to continue with the successful completion of each function block (ENO...enable out). Easier to keep using the same variable than creating a new one for each function block. Similar in concept to an array pointer that can be used in many loops.

Someone else with much more experience in Yaskawa MPiec controllers can correct me if needed.

 

[Highland Controls]

I think I know what he is trying to do, but not sure. Function blocks that use EN/ENO only get evaluated if EN is TRUE. Otherwise, the output is retained. What he is doing would make sense if you used different variables for each one and the EN/ENO was actually doing something here. With the first EN connected to the left power rail, ENO will always be TRUE.