There maybe a RS232 or RS485 interface between two equipments, and also there are two DC power lines delivering 12V or 24V between the two equipments. If four wires are not permitted caused by engineering condition limit, below DC PLC solution can be a good choice when the distance is not too long (Long distance application needs to consider our other solution)

suggested DC PLC chip


with a simple SO8 amplifier chip, This DC PLC chip can achive 115.2kbp on 24V DC power line over 30m distance. Also, the DC voltage level is flexible which can be 12V, 24V, 36V, 48V or higher. An idea low cost solution for short distance DC power line communication application 






If long distance DC power line communication solution needed, please consider below solution which can achieve 3km long distance