Normally closed stop buttons are always entered as normally closed contacts on a PLC.

Question

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Normally closed stop buttons are typically entered as normally open contacts in a PLC program to ensure that the circuit is active (allowing the PLC to run) when the button is not pressed, and the circuit becomes inactive (stopping the PLC) when the button is pressed. This is a safety design principle to ensure that any failure in the button (e.g., wire break) results in the machine stopping.

Normally Closed Stop Buttons Are Always Entered as Normally Closed