A method and a device for power-saving operation of a plurality of RFID data carriers, whereby the RFID data carrier has a transmission and reception antenna, by way of which data are sent to and received from a read/write unit, by means of a radio signal, and the data carrier is configured for reception of an energy-saving signal that puts the data carrier into a so-called sleep mode. The read/write unit sends a so-called conditional sleep command to all the RFID data carriers, and the RFID data carriers receiving these data in the transmission field compare the transmitted condition with a status/data detected in the RFID data carrier, whereby the condition detected in the RFID data carrier depends on a sensor input that is connected with the RFID data carrier. The transmission of the signals between the read/write unit and the data carrier is formed by means of a transmission/reception antenna disposed on the read/write device, and a correspondingly disposed transmission and reception antenna disposed on the data carrier.