Abstract: A method of mapping addresses of a plurality of refrigerated containers having remote monitoring units (RMUs) connected to a power line carrier based monitoring system which includes a master monitoring unit (MMU). The method adapts to the size of the expected number of containers to be mapped by any mapping command, to reduce the overall time to map either a large or small number of containers. The method includes the MMU selecting a modulo having a magnitude determined by the number of containers expected to be mapped, and the RMUs generating a random number within the range responsive to the modulo. The RMUs apply response messages to the power line, which include the addresses of the associated containers, at a time responsive to the magnitude of the random number.