A programmable interface circuit includes channel(s) including a digital logic block having terminals for receiving control signals from a process controller block, for providing logic signals, and terminals for receiving processed signal data. An analog logic block includes a current output digital to analog converter (DAC). An output circuit block includes first and second field terminals (S1,S2) and a sense resistor, wherein current from the DAC is coupled to S1 and the sense resistor is coupled to S2. The analog logic block includes a first and a second multi-channel multiplexer (MUX), an operational amplifier, and an analog to digital converter (ADC). The control signals automatically select from signal modes including an analog output (AO) mode, a digital output (DO) mode, an analog input (AI) mode, a digital input (DI) mode, and at least one additional signal mode provided by adding a sub-mode to the AI mode or DI mode.