A receiving unit for a controller for reception of input data is disclosed. The input data is transmitted as optical signals in an optical bus system in a vehicle. The receiving unit is coupled to an optical bus system and has a means for conversion of optical signals to electrical signals. A measurement arrangement is provided which measures a characteristic variable for the optical received power. The receiving unit optimizes the dynamic control of the optical level. The measurement arrangement is in the form of a digital circuit. Furthermore, an output port is provided for passing on the digitized measurement data.