An industrial automation input/output, I/O, module comprising: a body defining an internal space including a plurality of slots; a module backplane connector connected to said body; a primary backplane interface circuit board located in said space of said body, said primary backplane interface circuit board electrically connected to said module backplane connector and comprising electronic devices configured to transmit data and power to and from the backplane circuit through said module backplane connector; a plurality of individual I/O circuit boards installed respectively in said plurality of slots of said body, each of said I/O circuit boards comprising electronic devices configured to provide a single-channel I/O circuit for input or output of data with respect to an associated field device, wherein: each of said I/O circuit boards is electrically connected to said primary backplane interface circuit board when installed in a respective one of said slots, and each of said plurality of I/O circuit boards is selectively removable from its respective slot and from said internal space of said body for selective electrical disconnection of said I/O circuit board from said primary backplane interface circuit board; and a plurality of wiring connectors respectively removably engaged with the plurality of I/O circuit boards, each of said wiring connectors comprising at least one wiring terminal adapted to be electrically connected to a field line of an associated I/O field device, wherein each of said wiring connectors is received and retained in a respective slot by means of a releasable engagement with the body whether or not an I/O circuit board is installed in the slot, wherein each of said I/O circuit boards comprises an interface connector comprising interface contacts and each of said wiring connectors comprises wiring connector contacts, and wherein if an I/O circuit board is fully installed in a slot, a wiring connector will engage an interface connector of the respective I/O circuit board when the wiring connector is installed in the respective slot, such that the respective interface contact and the respective wiring connector contact operably mate, and wherein each of said wiring connectors is selectably removable from a respective slot with or without removing a corresponding associated I/O circuit board from the same slot. a body defining an internal space including a plurality of slots; a module backplane connector connected to said body; a primary backplane interface circuit board located in said space of said body, said primary backplane interface circuit board electrically connected to said module backplane connector and comprising electronic devices configured to transmit data and power to and from the backplane circuit through said module backplane connector; a plurality of individual I/O circuit boards installed respectively in said plurality of slots of said body, each of said I/O circuit boards comprising electronic devices configured to provide a single-channel I/O circuit for input or output of data with respect to an associated field device, wherein: each of said I/O circuit boards is electrically connected to said primary backplane interface circuit board when installed in a respective one of said slots, and each of said plurality of I/O circuit boards is selectively removable from its respective slot and from said internal space of said body for selective electrical disconnection of said I/O circuit board from said primary backplane interface circuit board; and each of said I/O circuit boards is electrically connected to said primary backplane interface circuit board when installed in a respective one of said slots, and each of said plurality of I/O circuit boards is selectively removable from its respective slot and from said internal space of said body for selective electrical disconnection of said I/O circuit board from said primary backplane interface circuit board; and a plurality of wiring connectors respectively removably engaged with the plurality of I/O circuit boards, each of said wiring connectors comprising at least one wiring terminal adapted to be electrically connected to a field line of an associated I/O field device, wherein each of said wiring connectors is received and retained in a respective slot by means of a releasable engagement with the body whether or not an I/O circuit board is installed in the slot, wherein each of said I/O circuit boards comprises an interface connector comprising interface contacts and each of said wiring connectors comprises wiring connector contacts, and wherein if an I/O circuit board is fully installed in a slot, a wiring connector will engage an interface connector of the respective I/O circuit board when the wiring connector is installed in the respective slot, such that the respective interface contact and the respective wiring connector contact operably mate, and wherein each of said wiring connectors is selectably removable from a respective slot with or without removing a corresponding associated I/O circuit board from the same slot.