A method of simulating a sequential control program by composing simulation ladder program elements with timer elements which correspond to the ladder program elements of the sequential control program. If the operations of a plurality of operation steps are performed in parallel with each other, a time...http://www.google.de/patents/US5173869?utm_source=gb-gplus-sharePatent US5173869 - Method of simulating a sequential control for analyzing a production line in a production system
