High Availability Device Level Ring Backplane

An industrial control system comprising:

• a plurality of banks, each bank including a plurality of I/O bases, each I/O base module having a first port, a second port, and a bus slot, the bus slot for releasably receiving a function card having a switching node, wherein each I/O base module couples the first port and the second port to the switching node when the function card is installed in the bus slot, and each I/O base module couples the first port to the second port when the function card is absent from the bus slot, at least one I/O base module having a function card installed in the bus slot;
• wherein the first bank includes an adapter base module having a first port, a second port, a switching node and a network adapter, the switching node coupled between the first port and the second port and in communication with the network adapter, the network adapter operable to communicate over a control network;
• and
• wherein the adapter base module in the first bank has a second port coupled to the first port of an I/O base module in the same bank, the second port of each I/O base module in each bank is coupled to the first port of the next I/O base module in the same bank, except the last I/O base module in each bank having the second port coupled to the first port of the first I/O base module in the next bank, except the last I/O base module in the last bank having the second port coupled to the first port of the adapter base module in the first bank to form a network ring of switching nodes.

An I/O base module for an industrial system comprising:

• an enclosure providing left and right flanking sides;
• releasable electrical connectors supported on the left and right flanking sides exposed to connect adjacent base modules on the left and right sides;
• a releasable mechanical connector for holding the base module to adjacent base modules on the left and, right sides;
• a plurality of electrical terminals for receiving conductors exposed on a surface of the enclosure to releasably retain electrical conductors communicating with an I/O function card held within the enclosure;
• and
• backplane circuitry held within the enclosure and communicating with the releasable electrical connectors to establish a ring network communicating among attached base modules to provide a first port at one electrical connector and a second port at the second electrical connector so that the base modules may be arranged in a ring wherein the first and second ports of each base module couple to a different base module of the ring.