Modular input/output system with flexible interface with field wiring

A modular I/O system for field wiring comprising:

• a controller;
• a plurality of modular I/O units each comprising:
• a base member;
• backplane mounted in said base member;
• an electronics module including a signal processing circuit mounted on said base member via a first circuit connector disposed on said base member;
• a plurality of terminals mounted on said base member wherein each of the plurality of terminals includes a contact adapted to make an electrical connection with the field wiring;
• a personality module removably mounted on a second circuit connector disposed on said base member;
• an interface circuit housed in said personality module;
• a first plurality of electrical conductors disposed on said backplane extending between said terminals and the second circuit connector;
• a second plurality of electrical conductors disposed on said backplane extending between the second circuit connector and the first circuit connector;
• wherein the first and second plurality of electrical conductors and the first and second circuit connectors provide electrical connections between said terminals, the personality module, and said electronics module, wherein said interface circuit of said personality module provides an interface between said electronics module and said field wiring connected to said plurality of terminals to change a property of the electrical connection between said electronics module and said field wiring;
• and
• an electrical connection that electrically connects said plurality of modular I/O units to said controller.