A universal input/output circuit for building automation is provided that may avoid issues related to capacitor soakage, thereby giving more accurate measurements of electric resistance. To mitigate capacitor soakage, the voltage between the input/output terminals is held constant. A programmable source drives a current through a resistor that connects to the input/output terminals. The circuit then measures a value of electrical resistance. The measurement yields a voltage signal which is transferred from the input of an analog-to-digital converter to the input of a digital-to-analog converter. A unity gain amplifier applies the output voltage of the digital-to-analog converter D/A to one of terminals. The circuit is configured such that the voltage signal at the output of the amplifier matches or substantially matches the voltage obtained from the resistance measurement.

A universal input/output circuit for building automation is provided that may avoid issues related to capacitor soakage, thereby giving more accurate measurements of electric resistance. To mitigate capacitor soakage, the voltage between the input/output terminals is held constant. A programmable source drives a current through a resistor that connects to the input/output terminals. The circuit then measures a value of electrical resistance. The measurement yields a voltage signal which is transferred from the input of an analog-to-digital converter to the input of a digital-to-analog converter. A unity gain amplifier applies the output voltage of the digital-to-analog converter D/A to one of terminals. The circuit is configured such that the voltage signal at the output of the amplifier matches or substantially matches the voltage obtained from the resistance measurement.