A modular, high-availability network for an industrial control system employs a plurality of base modules having backplane and using network ring topology. Base modules may include I/O base modules for communicating with industrial processes or machines, an adapter base module for communicating with a programmable logic controller (PLC) and/or a bus expansion base module for providing additional I/O base modules. Base modules may be arranged side-by-side, having a backplane in a bank. Another embodiment may include having plurality of banks. The network ring topology used by the base modules is normally opened by a ring supervisor at the ring supervisor location. Upon failure of the network, the ring supervisor reconnects the ring to provide an alternative transmission path around the failure point.