The Single Input Device is designed to monitor the state of one or more single pole, voltage free contacts connected to a single pair of cables and to report the status to the Ampac fire detection control panel. Monitoring of the external cables is provided for open and short circuit fault conditions and the input circuit itself is conditioned with de-bounce circuitry for enhanced noise rejection. The input circuit is also protected against high transient voltages. The Ampac Single Input Device is loop powered and incorporates bi directional isolation circuitry to provide protection against detection loop short circuits. On board LED status indication is provided for service and commissioning purposes, a feature that can be deactivated during normal operation to reduce the current draw on the system. Two packaging options are available. The 'DIN Mount' version enables the device to be mounted onto standard 35mm DIN rail or screwed direct to the back pan of a larger enclosure while the 'Enclosed' version allows the device to be surface mounted to a wall.