A control unit for controlling and/or regulating at least one vehicle function, including at least one computing element and one transceiver for connecting the control unit to at least one data line of a data bus of a client-server network. Using at least one transmitted signal and at least one received signal, the at least one computing element determines if the transceiver is transmitting or receiving data via the at least one data line. In order to provide the option of being able to ascertain the transmitted and received signals without having to pick them off in the interior of the control unit and to direct them outwards, the control unit is connected to the data line via a measurement set-up, the measurement set-up having an arrangement for determining if a change in the state of a data signal applied to the data line originates at the control unit or at the rest of the client-server network.