Single channel I/O in a modular sub-chassis

An industrial automation input/output (I/O) module includes a body defining an internal space including a plurality of slots. A module backplane connector is connected to the body, and a primary backplane interface circuit board is located in the space of the body. The primary backplane interface circuit board is electrically connected to the module backplane connector and includes electronic devices configured to transmit data and power to and from an associated backplane circuit through the module backplane connector. A plurality of individual I/O circuit boards are installed respectively in the plurality of slots of the body. Each of the I/O circuit boards includes electronic devices configured to provide a single-channel I/O circuit for input or output of data with respect to an associated field device. Each of the I/O circuit boards is electrically connected to the primary backplane interface circuit board when installed in a respective one of said slots, and each of the plurality of I/O circuit boards is selectively removable from its respective slot and from the internal space of the body for selective electrical disconnection of said I/O circuit board from the primary backplane interface circuit board.