Patent ID: 7307520

Claim:
A communications system comprising a. an input device coupled to a power source by a load power bus, the load power bus comprising a direct current (DC) power bus; and b. an output device coupled to the input device and to a load by the load power bus and to the power source by a return power bus, the output device comprising i. a filter for receiving a command signal of a pre-determined frequency transmitted by the input device over the load power bus and filtering signals that are not of the pre-determined frequency, ii. a receive detector for receiving signals from the filter and determining if the signals match the pre-determined frequency and outputting a signal of the pre-determined frequency corresponding to the command, iii. a controller for receiving the command from the receive detector to filter out the command and, iv. a transmit driver downstream of the controller to prepare messages received from a main processor for injection back into the load power bus, and v. the main processor for communicatively receiving and sending said messages with said controller.