Safety gate logic

[milmat1]

I have a safety gate that will use a locking keyed gate switch. The gate locks via a 24VDC solenoid lock. And is monitored by the 2 OSSD outputs by a safety relay.

The question I have is whether the locking signal (that actually locks the gate) has to come from a safety output ?

Can I lock the gate with a standard PLC output, and monitor the status with the OSSD's to safety inputs ?

 

[DBill64]

The locking signal would have to originate from a safety output, so normal PLC output would not be fine. I would also add a sensor to detect actual gate position during operation (i.e. inductive sensor on the gate, mag switch, etc.) that would trigger the shutdown sequence if the gate were opened regardless of the lock position. That should get you a category 3 (perhaps cat 4?) safety circuit which should be fine. https://www.schmersalusa.com/fileadmin/content/usa/downloads/technical-articles/ExecSummary_ControlReliable_103024.pdf#:~:text=Consider a Category 3 safety circuit being,during operation, a safe stop is triggered.
See page 5 for examples. Hope this helps!