An analog signal input circuit to process analog input signals relevant for the safety of a process, with a first number of at least two analog signal detection channels (100; 100'), which can be operated redundantly or can be connected to form a redundancy block, wherein - each analog signal detection channel (100; 100') being embodied to detect an analog input signal applied at an analog signal input from a second number of analog signal inputs (201, 202; 201', 202') and, responding to a detected analog input signal, issuing an output signal; - each analog signal detection channel (100; 100') respectively including two analog signal detection circuits (110, 120; 110', 120'), at least one diagnostics circuit (130; 130') and at least one first connection selection device (115, 125); - each analog signal detection circuit (110, 120; 110', 120') comprising a first connection device (111, 121) and a second connection device (112, 122); - each of the analog signal detection circuits (110, 120; 110', 120') of an analog signal detection channel (100; 100') being able to connect to its first connection device (111, 121) with the same analog signal input of the second number of analog signal inputs (201, 202; 201', 202') for detecting an analog input signal, at least successively, and both analog signal detection circuits (110, 120; 110', 120') of an analog signal detection channel (100; 100') being embodied such that, responding to detected matching analog input signals, issuing at their second connection devices (112, 122) matching output signals; - each analog signal detection channel (100; 100') for the detection of the analog input signal applied at one analog signal input from the second number of analog signal inputs and for the responding output of the output signal for the detected analog input signal respectively one of the two included analog signal detection circuits is selected alternatingly for a certain period of time, not connected to its first connection device with this analog signal input for detecting this analog input signal, but used for test and/or diagnostic purposes, and the respectively other of the two included analog signal detection circuits (110, 120; 110', 120') is selected for this certain period of time to be connected to their first connection device with this analog signal input for detecting this analog input signal and responding to the detected analog input signal issuing the output signal of the analog signal detection channel at this second connection device as the output signal, with the first connection selection device (115, 125) being embodied for the purpose of connecting the respectively first connection device (111, 121) of the two included analog signal detection circuits (110, 120; 110', 120') in response to the selection at least to either the analog signal input to be connected or to the diagnostics circuit for introducing test and diagnostic signals. - each analog signal detection channel (100; 100') being embodied to detect an analog input signal applied at an analog signal input from a second number of analog signal inputs (201, 202; 201', 202') and, responding to a detected analog input signal, issuing an output signal; - each analog signal detection channel (100; 100') respectively including two analog signal detection circuits (110, 120; 110', 120'), at least one diagnostics circuit (130; 130') and at least one first connection selection device (115, 125); - each analog signal detection circuit (110, 120; 110', 120') comprising a first connection device (111, 121) and a second connection device (112, 122); - each of the analog signal detection circuits (110, 120; 110', 120') of an analog signal detection channel (100; 100') being able to connect to its first connection device (111, 121) with the same analog signal input of the second number of analog signal inputs (201, 202; 201', 202') for detecting an analog input signal, at least successively, and both analog signal detection circuits (110, 120; 110', 120') of an analog signal detection channel (100; 100') being embodied such that, responding to detected matching analog input signals, issuing at their second connection devices (112, 122) matching output signals; - each analog signal detection channel (100; 100') for the detection of the analog input signal applied at one analog signal input from the second number of analog signal inputs and for the responding output of the output signal for the detected analog input signal respectively one of the two included analog signal detection circuits is selected alternatingly for a certain period of time, not connected to its first connection device with this analog signal input for detecting this analog input signal, but used for test and/or diagnostic purposes, and the respectively other of the two included analog signal detection circuits (110, 120; 110', 120') is selected for this certain period of time to be connected to their first connection device with this analog signal input for detecting this analog input signal and responding to the detected analog input signal issuing the output signal of the analog signal detection channel at this second connection device as the output signal, with the first connection selection device (115, 125) being embodied for the purpose of connecting the respectively first connection device (111, 121) of the two included analog signal detection circuits (110, 120; 110', 120') in response to the selection at least to either the analog signal input to be connected or to the diagnostics circuit for introducing test and diagnostic signals.