Abstract: A programmable channel circuit can include a control circuit having at least one bidirectional I/O terminal, at least one programming terminal, and one or more processing elements, and an interface circuit having first and second field terminals/The interface circuit is coupled to the control circuit via the processing elements. The control circuit can be operable to respond to a programming signal on the programming terminal for automatically selecting one of a plurality of communications modes. The selection couples the bidirectional I/O terminal to the first terminal via one of the processing elements associated with the selected communications mode.