A universal I/O interposer system for processing an I/O signal transmitted between an I/O field device and a controller, the system includes a base connected between the field device and the controller and a number of connector halves attached to the base. An interposer circuit carrier includes a corresponding connector half and includes a signal processing circuit for processing an I/O signal being transmitted between an I/O field device and a controller. An interposer circuit carrier can be changed without disconnecting the base from the field device or controller.