| 摘要 |
PURPOSE:To test easily an unattended terminal device by inverting the feeding polarity from an exchange station, applying a power to a power reception circuit of a terminal device to bring the terminal device into the operating state and obtain the response signal. CONSTITUTION:When a test command signal TST is supplied to a test circuit 13 of an exchange station 1, a power feeding polarity inversion command is fed from the circuit 13 to a transmission/reception circuit 12 and the polarity of subscriber lines (a), (b) is inverted from -, + into +, -. Then a power is fed to the power reception circuit 21 to the exchange station 1 via a diode circuit 22 of a terminal device 2 and the circuit 21 is brought into the operating state. The circuit 13 generates test information and when it is fed to the terminal device 2 via the circuit 12, a test response circuit 27 of the terminal device 2 receives the test information via the transmission/reception circuit 25, generates response information corresponding to the test information and transmits it from the circuit 25 to the exchange station 1. The circuit 13 of the exchange station 1 receives the response signal via the circuit 12 to decide the abnormity of the terminal device 2. |
