Impedance upper connected to distribution panel of existing wire communication system

A conventional wire communication system communicates between powered terminals via a main unit. In this system, the main unit communicates with the powered terminal by changing the voltage signal to the positive and the negative. The powered terminal communicates with the main unit using the reply current signal. Because this system is used for on-off control, the communication speed is slow. Therefore, we proposed an add-on type multiplex module to be able to perform communications at speeds higher than existing systems. The multiplex module communicates by increasing the input impedance. However, the existing system has a terminal with low impedance. In this paper, we propose the impedance upper is connected to the distribution panel for steady communications, and describe the basic characteristics.