Danger indicator or alarm has at least one sensor for a danger characterizing quantity, evaluation electronics for evaluation of the sensor signal, an optical alarm indicator (1) and a communications interface (KM) for wireless two way communication between the danger indicator and an operating module. The communications interface has an optical transmission channel (KMo) formed by the alarm indicator and an inductive receiver channel (KMi). An Independent claim is included for a corresponding operating module for a danger indicator with a receiver in the form of a photo-diode and a transmitter in the form of an inductor (9).