The circuit arrangement of the invention consists of a central unit (5) and a plurality of peripheral units, e.g. control devices for lamps, connected thereto via a databus. The lamps are connected to the databus (1) via a coupling unit (3), each coupling unit (3) having a reception branche for the transfer of information from the central unit (5) to the peripheral unit and a transmission branche for the transfer of information from the peripheral unit to the central unit (5). The central unit (5) provides the databus with information in the form of a modulated alternating or pulsed voltage. The transmission branch provides the databus (1) with information by varying the output resistance of the transmission branch. As the reception branch in the coupling unit (3) is always active and the transmission branch is inactive when no transmission are being made, only a very low reverse current is used in the coupling unit (3). Finally, on overvoltage protective circuit is fitted for both the reception and the transmission branch.