Patent ID: 8693555
Filing Date: 2014-04-08
Classification: H04B,H04L

Abstract:
1. A communication system having a plurality of communication terminals connected to a two-wire communication line and a power supply apparatus that applies a voltage between two wires of said communication line, the communication system further having: a current/voltage conversion unit that converts current change on said communication line into voltage change on said communication line by means of a voltage drop in an impedance component, wherein said communication terminal comprises: a signal generation unit that generates a communication signal on the basis of information to be transmitted; a first transmission unit that is connected to said communication line and transmits a current signal to said communication line by changing a current flowing from said communication line in accordance with variation in said communication signal; a second transmission unit that is connected to said communication line and applies said communication signal to said communication line as a voltage signal transmitted from said second transmission unit; a receiving unit that receives a voltage signal of voltage change into which said current signal transmitted from said first transmission unit is converted through said current/voltage conversion unit, and also receives said voltage signal transmitted from said second transmission unit; and a communication method switching unit that switches between a current transmission method in which said communication signal is transmitted through said first transmission unit and a voltage transmission method in which said communication signal is transmitted through said second transmission unit in accordance with a predetermined communication switching rule.