An interface apparatus is provided having a first register device and a second register device, which is connected in parallel with it. The register devices are configured to receive a data word. The interface apparatus includes a synchronization circuit, to which a first and a second clock signal is supplied and which is configured to emit a selection signal, which is derived from the first clock signal, for selection of the first or second register device for storage of a data word. The synchronization circuit is also configured to emit a control signal derived from the selection signal and the second clock signal, at a control output. The control output is coupled to a selection circuit, by means of which the output of one of the two register devices can be connected to the data output of the interface apparatus. Comparison of the selection signal with the second clock signal means that there is no need for an additional registration device.