Abstract: A system an analog to digital converter (ADC) operatively connected to receive an analog input signal from an input line and to output a digital input signal. A processor is operatively connected to receive the digital input signal from the ADC and to output a digital control signal for controlling a physical system based on the digital input signal. A digital to analog converter (DAC) is operatively connected to receive a copy of the digital input signal put out from the processor, and to output an analog output signal indicative of the copy of the digital input signal put out from the processor. Comparison logic is operatively connected to receive the analog input signal from the input line, to receive the analog output signal from the DAC, and to output an error signal in response to a mismatch between the analog input signal and the analog output signal.