[cgranata]

The pressure switch for the compressor turns your compressor on when the PSI dips to around 90 PSI and turns the compressor off when it hits around 115 PSI.

No it does not connect to the cRIO.

You wire the pressure switch as follows:
1. Take a PWM cable and cut off the male end (the end with the prongs)
2. Strip the white and black ends of the wire you just cut.
3. Connect signal (white) to NC (labeled on the switch itself)
4. Connect ground (black) to C (labeled on the switch itself)
5. Connect the other end of the cable (the female side) to the Digital I/O port on the Digital Sidecar. There is a key on the Digital Sidecar that shows you how to correctly plug in the cable.

That is how you wire the pressure switch.