Communications device having an optical bus, and a method for controlling its operation

An electronic communications device contains at least two modules (7, 8) which are connected to one another via an optical bus (4). In an energy-saving mode, each of the modules (7, 8) is switched to receive with a sampling period (P) which is the same for all modules (7, 8), and for a sampling time interval (T) which is short in comparison with the sampling period (P). One of these modules (7, 8) sends an interrupt signal (I) to the optical bus (4), whose duration is equal to or longer than the sampling period (P). At the latest on reception of the interrupt signal (I), the other module (7, 8) is switched to permanent receive in the next sampling time interval, so that data communication can then take place via the optical bus (4).