A method and system for assigning slot addresses to modules in a fault tolerant industrial control system includes a pair of backplane switches on each base. Each backplane switch is configured to communicate between one backplane and the modules located on the base and to communicate between backplane switches located at adjacent bases. A backplane switch on a bank master base first assigns a base address and slot addresses to itself. The backplane switches on each additional base initiate transmission of a base address request. A base address response, including a base address and slot numbers for the adjacent base, is transmitted after a base has its own address assigned. Each base repeats the process in sequence along the bank, incrementing the base address by one and the slot address by the number of slots on the base and passing the new base and slot addresses along the bank.