A method of one-line power mapping in a datacenter includes providing from a management system a pre-defined pattern to a rack system, in response to providing the pre-defined pattern, directing the rack system to enable a power supply unit of the rack system and to modulate a power usage of the rack system to encode the pre-defined pattern onto a power cable, wherein the power supply unit receives operating power from a power distribution unit via the power cable, receiving at the management system a power level signal from the power distribution unit, decoding at the management system the pre-defined pattern from the power level signal, and determining that the rack system is connected to the power distribution unit in response to decoding the pre-defined pattern.