An interface module is proposed, to which sensors are connected and which is positioned in a control device, it being indicated via an identification input how the sensor data are to be classified by the interface module. In particular, this can be used to distinguish between safety-relevant and safety-irrelevant data. Furthermore, the nature of the data can be identified therewith. This identification input is advantageously designed as a voltage input, the voltage levels being then converted into a bit sequence. The identification input is connected to ground via a resistor, so that, in the case of an unspecified input potential, the voltage level is connected to ground. The interface module has a logic circuit to which voltage comparators are connected, which compare the voltages to reference potentials, and then the logic circuit performs a coding using the bit sequences, as a function of the output signals of the voltage comparators.