The OmniLogic has an External Input Interlock contact that can be used to configure software interlocks to shutdown equipment of your choice; maybe this is what you’re referring to? You could certainly use this to implement an emergency stop switch if you wanted to. In my example case, I have a whole-home generator that performs load shedding if the draw gets too high. I have this wired to the external input on the OmniLogic, where I have interlocks configured to shut down the pumps if the load shed triggers.
Here’s an excerpt from the OmniPL manual; it’s the same as the OmniLogic: