Power line communication (PLC) coupling through an external power supply

Systems and methods according to aspects of the subject technology provide for power line communication (PLC) coupling through two-wire and three-wire external power supplies. In some aspects of the subject technology, a three-wire solution is provided that allows the transfer of direct current (DC) power signals, differential PLC signals, and a zero-cross signal between an external power supply and a PLC device using three wires. This may be accomplished by multiplexing two signals on two of the three wires. In some aspects of the subject technology, a two-wire solution is provided that allows the transfer of DC power signals, differential PLC signals, and a zero-cross signal between an external power supply and a PLC device using two wires. This may be accomplished by multiplexing two signals on one of the wires and three signals on the other wire.