Transforming ladder diagram into software commands

Thread Starter


Joined Apr 22, 2011
Hey guys. I'm working with a PLC without any buttons. Now, I've written two different ladder diagrams to do two different actions.

Problem is, I don't know how to integrate it to a simple software interface. Right now, every time I want to switch between the programs I need to recompile the program to do either action 1 or action 2 and tell the PLC "run". Provided I'm not allowed to add buttons/switches/anything mechanical, how do I make it so I can easily control the PLC via a software?


Joined Feb 24, 2006
The whole idea of ladder diagrams, as with other hardware implementations is that everything runs in parallel. In order to control something there must be some kind of input; perhaps you can control internal words from a console.


Joined Jul 18, 2013
As Papabravo mentions, it requires a stimulus of some kind, what type of PLC and what software?
With physical inputs you can operate manually when required, if no external type accessible then it would have to be done internally by a timer or counter or other work around for e.g.