This work investigates a power line communication (PLC) in a DC power management system comprising master-slave control networks. Microcontroller-based master and slave units are designed with serial ports for communication with a controller and a transmission port to couple the signal to modems at both ends. However, coupling data signals to power line through modulation interfacing circuits is a challenging task. In this work, we used time-division multiplexing (TDM) technique to divide into two timings, Powering Time and Communication Time, on the DC power line and can reduce the complexity of the master-slave network and noise effect on the power line.