The invention creates a control and evaluation apparatus for different sensor units, having: a stabilized supply unit for supplying the sensor unit with electrical energy; an amplifier device for amplifying a sensor signal generated by the sensor unit, which signal is delivered to the amplifier device as an input signal, and for outputting a measured signal dependent on the sensor signal; and an output unit for outputting the amplified sensor signal as an output signal. The amplifier device contains an integrated measuring resistor for measuring a voltage drop produced by the sensor signal, the voltage drop being delivered to the amplifier device as the input signal. In addition, in a comparator unit downstream from the amplifier device, the measured signal is compared with a definable threshold value, the threshold value being adjustable as a function of the sensor unit being used.