The CS1124 is a monolithic integrated circuit designed primarily to condition signals used to monitor rotating parts. The CS1124 is a dual channel device. Each channel interfaces to a Variable Reluctance Sensor, and monitors the signal produced when a metal object is moved past that sensor. An output is generated that is a comparison of the input voltage and the voltage produced at the INAdj lead. The resulting square-wave is available at the OUT pin. When the DIAG pin is high, the reference voltage at INAdj is increased. This then requires a larger signal at the input to trip the comparator, and provides for a procedure to test for an open sensor.