Abstract: Test device having a signal input with a positive pin and a negative pin, between which an-input signal may be applied. Test device has a separation unit which is connected to the positive pin and to the negative pin and is configured to separate a positive signal component in the form of a positive track from the input signal, to output said signal component at a first pin, to separate a negative signal component in the form of a negative track from the input signal and to output said signal component at a second pin. The use of the test device to test a control unit of the switching device is described, wherein the test device simulates the switching device, the signal input of the test device is connected to the control unit and the control unit outputs an input signal to the signal input.