A programmable interface circuit (100) includes channel(s) including a digital logic block (110) having terminals (116e) for receiving control signals from a process controller block (170), terminals (111, 112) for providing logic signals (111a, 112a), and terminals for receiving processed signal data. An analog logic block (120) includes a current output digital to analog converter (DAC) (121). An output circuit block (140) includes first and second field terminals (S1,S2) and a sense resistor (146), 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) (131, 132), an operational amplifier (135), and an analog to digital converter (ADC) (122). 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.
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