| 摘要 |
PURPOSE:To attain reverse control by controlling a network and transmitting a reverse signal to attain the reverse control. CONSTITUTION:When terminal groups A, B are accommodated respectively to incoming and outgoing sides of the network NW, and a terminal device Bn requiring the transmission of the reverse signal is accommodated in the network NW; two terminals for normal and reverse use are provided as terminals of the outgoing side, and the latter is connected by reversing the connection of lines A and B to that of the former. In transmitting the reverse signal from the terminal device Bn, cross points POA, POB for normal connection are restored and cross points P1A, P1B for reverse connection are operated, allowing to invert the polarity of the voltage of power supply for line A and the earth to line B, and the result is transmitted to a terminal device A0. The reversed signal is transmitted while the connection is changed to the reverse terminal in this way and a relay for reverse signal transmission and a relay drive circuit at the terminal device B are not required. |
