The transponder holder is equipped with a slot into which the transponder card is inserted. In a hotel application, this allows occupancy recognition and notification at the supervisory level (e.g. on the front desk computer). Moreover, room status information can be managed by using special cards (minibar status, maintenance status, usability). The device is equipped with two bistable relays (8 A, 250 Vac), and three voltage-free, non-optically insulated inputs; the 5-Vdc scanning voltage is generated by the device itself. The transponder holder has on the front four LEDs for signaling indications. It requires a 10...32Vdc/12...24Vac auxiliary power supply to ensure its operation even in case of KNX voltage failure.