Patent ID: 7719255

Claim:
Input circuit for an input component for the safe reading of input signals applied to the input component, the input circuit comprising: a signal input circuit ( 110 ) with a one-channel periphery connection (INO) for the connection of at least one signal generator; an evaluation circuit ( 120 ), which is connected electrically to the signal input circuit ( 110 ) via a first coupling element (IC 1 ); a comparison circuit ( 200 ), which is electrically connected to the signal input circuit ( 110 ), for setting a reference voltage for the activation or deactivation of the coupling element (IC 1 ); and a test circuit ( 300 ), which is connected electrically to the signal input circuit, for testing the first coupling element (IC 1 ), wherein the test circuit ( 300 ) for testing the first coupling element (IC 1 ) presents a third coupling element (IC 3 ), through which a test voltage can be applied to the first coupling element in the signal input circuit.