An analog signal input circuit with a first number of analog signal detection channels and a diagnostics circuit, with each analog signal detection channel including a third number of analog signal detection circuits and a first connection selection device, and each analog signal detection circuit comprising a first connection device and a second connection device. For each analog signal detection channel, for detecting analog input signals applied at analog signal inputs from a second number of analog signal inputs, and for the respective issuance of output signals for the detected analog input signals, respectively one analog signal detection circuit is alternatingly selected for a certain period of time, not connected to its first connection device comprising an analog signal input for detecting an analog input signal, but used for testing and/or diagnostic purposes.