A modular I/O system for an industrial automation network, said modular I/O system comprising: a network adapter including first and second adapter modules (112b1, 112b2), wherein each of the adapter modules is configured for operative connection with an associated industrial network (N1, N2); a first I/O device located adjacent to the network adapter and including first and second I/O modules (120b1, 120b2) each configured for operative connection to an associated controlled system for input and output of data with respect to the associated controlled system; first and second independent backplane data networks (114a, 114b) that operably connect each of the first and second adapter modules to each of the first and second I/O modules, wherein said network adapter and said first I/O device comprise respective first backplane connectors that are physically mated with each other and that establish part of said first and second backplane networks when mated with each other in a serial or daisy-chain manner, wherein said first I/O device further comprises respective second backplane connectors for physically mating corresponding second backplane connectors of a second I/O device and for establishing part of said first and second backplane networks when mated with said corresponding second backplane connectors of the second I/O device in a serial or daisy-chain manner, first and second network data switches (130a, 130b) physically connected to said network adapter, wherein said first network data switch is operably connected to said first backplane network and said second network data switch is operably connected to said second backplane network; and third and fourth network data switches physically connected to said first I/O device, wherein said third network data switch is operably connected to said first backplane network and said fourth network data switch is operably connected to said second backplane network, wherein said first and second network data switches are each operably connected to both of said first and second adapter modules of said network adapter for communication of data between each of said first and second network data switches and both of said first and second adapter modules. a network adapter including first and second adapter modules (112b1, 112b2), wherein each of the adapter modules is configured for operative connection with an associated industrial network (N1, N2); a first I/O device located adjacent to the network adapter and including first and second I/O modules (120b1, 120b2) each configured for operative connection to an associated controlled system for input and output of data with respect to the associated controlled system; first and second independent backplane data networks (114a, 114b) that operably connect each of the first and second adapter modules to each of the first and second I/O modules, wherein said network adapter and said first I/O device comprise respective first backplane connectors that are physically mated with each other and that establish part of said first and second backplane networks when mated with each other in a serial or daisy-chain manner, that are physically mated with each other and that establish part of said first and second backplane networks when mated with each other in a serial or daisy-chain manner, wherein said first I/O device further comprises respective second backplane connectors for physically mating corresponding second backplane connectors of a second I/O device and for establishing part of said first and second backplane networks when mated with said corresponding second backplane connectors of the second I/O device in a serial or daisy-chain manner, for physically mating corresponding second backplane connectors of a second I/O device and for establishing part of said first and second backplane networks when mated with said corresponding second backplane connectors of the second I/O device in a serial or daisy-chain manner, first and second network data switches (130a, 130b) physically connected to said network adapter, wherein said first network data switch is operably connected to said first backplane network and said second network data switch is operably connected to said second backplane network; and third and fourth network data switches physically connected to said first I/O device, wherein said third network data switch is operably connected to said first backplane network and said fourth network data switch is operably connected to said second backplane network, wherein said first and second network data switches are each operably connected to both of said first and second adapter modules of said network adapter for communication of data between each of said first and second network data switches and both of said first and second adapter modules.