PIRAC is an abbreviation for Passive Infra Red Auto Close. It is a mode of operation which will cause the gate to close immediately the infra red beam is cleared after an object has entered the beam. Any trigger to the control card will cause a closed or closing gate to open. If already opening, the trigger signal is ignored. If the gate is opened, but the beam is not broken, then the gate will immediately start closing when it reaches its programmed, fully open end point. It is thus a high security mode.