| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a communication system, capable of continuing communication even when power supply from a power supply device to a communication line is stopped, while maintaining communication even when the impedance of the communication line is reduced. <P>SOLUTION: A communication terminal T1 includes first and second transmission units Tx1, Tx2 for sending signals to a communication line W, first and second receiving units Rx1, Rx2 for receiving signals from another communication terminal T1, and a communication type switcher 13 for switching signal transmission types. The first transmission unit Tx1 sends a current signal to the communication line W. The first receiving unit Rx1 receives a voltage signal obtained by converting the current signal sent from the first transmission unit Tx1 by a current/voltage conversion unit 4. The second transmission unit Tx2 sends a communication signal to the communication line W as a voltage signal. The second receiving unit Rx2 receives the voltage signal transmitted from the second transmission unit Tx2. The communication type switcher 13 switches between a current transmission type for transmitting a signal by the first transmission unit Tx1 and a voltage transmission type for transmitting a signal by the second transmission unit Tx2. <P>COPYRIGHT: (C)2011,JPO&INPIT |
