System and method for automatically identifying slots in a backplane

Abstract

A computer controlled system has two or more secondary backplanes that are plugged into slots in a primary backplane. Board slots in the secondary backplanes are assigned unique addresses, and the range of addresses for each secondary backplane is contiguous with the range of addresses for a neighboring secondary backplane. Each slot in the primary backplane has one or more primary address pins. The primary address pins in the primary backplane slots are coupled so as to set the primary address pins in each primary backplane slot to a unique value. Each secondary backplane has a bus line for each primary address pin of the primary backplane slot into which it is plugged. The bus lines couple the primary address pins to board address identification pins, also called address pins, in certain of the board slots. Address pins are provided for each board slot, and are set to selected values for each board slot. Some of the address pins in each slot are set to a 0 or 1 binary value by connecting those pins to ground or leaving the pins to float to the pull-up voltage on the board. Others of the address pins in each slot are coupled to a respective one of the bus lines so as to set that address pin to a value that is determined by the primary backplane slot in which the secondary backplane is inserted.