
The article details a PLC program built in Siemens TIA Portal that uses latching and interlock logic to control a single pump via three RUN buttons. Pressing START sets a SYSTEM_ON memory bit, enabling the RUN inputs while STOP clears it. Each RUN button lights a dedicated lamp and latches its state, but interlocks prevent any other RUN button from activating simultaneously. The pump output energizes when any lamp is on, ensuring exclusive control.

The XG5000 PLC program implements a three‑floor cargo elevator that moves one floor at a time using up and down push‑buttons. Limit‑switch sensors on each floor provide position feedback, while a latched SYSTEM_ON memory bit keeps the controller active after...