A signal interface system and method of interfacing signal input sources with user output destination devices are provided. The signal interface system is configurable to accept one of a plurality of types of inputs. The signal interface system includes a common section, and a module section including two or more monitor modules. The two or more monitor modules condition a received signal for consumption by a user output destination device. The common input section allows monitor modules to be removed without impacting the function of other monitor modules in the system. The signal interface accepts either discrete inputs or process variable current inputs.