When a PLC is used primarily to replace relays, timers, and counters, it's hard to beat the simplicity and usefulness of ladder diagram programming. Their ability to accept programming in ladder ...

If they do, the problem is on the processor side of the input module. Next, watch the PLC logic for a corresponding change. If it doesn't happen, then the signal isn't making it from the input module ...

WPLSoft is a fully-featured free PLC simulation software. You will find all the ladder logic functions here, such as bit logics (NO, NC, set coil, normal coil, reset coil), mathematical operators ...