Is it possible to bring in sensor inputs from something like a proximity switch on the pokeys?

What kind of output does this switch have?

If it has an analog output use the appropriate voltage attenuator first and connect it to the analog input pin (PoKeys has the limit of max. 3.3V on those pins).
If the switch has 4-20mA current output, use an appropriate resistor and connect it to the analog input pin similarly as above.

Give more details on the proximity switch to help you further.

Matevž, PoLabs

Prox's usually run at 24vdc (sinking or sourcing), to interface to the PK, you could
do it through a Solid state relay, or if speed not real important, a standard relay.

Scott