A modular I/O device includes a terminal base with a terminal block that includes a plurality of wiring connectors. An auxiliary wiring device includes a plurality of auxiliary wiring connectors and is selectively physically connectable to the terminal base in an operative position and selectively physically removable from the terminal base. The terminal block and auxiliary wiring connector can be coupled to an I/O module. One or more of the I/O module terminal block and auxiliary wiring connector can include electrical or electronic components included converters, fuses, switches, etc.