According to certain embodiments, a system comprises a primary unit and a plurality of secondary units each having a unique unit number. The primary unit is configured to communicate a command to each secondary unit with instructions to reply during a time window. The primary unit is also configured to receive a reply communication indicating the secondary unit's unique unit number from at least one of the secondary units, and determine an address to assign to the replying secondary unit based at least in part on the received unique unit number.