| 摘要 |
PROBLEM TO BE SOLVED: To immediately detect a fault while distinguishing a broken line, a short-circuit of a trunk line interconnecting a master set and a controller, and a terminal and the controller and a circuit fault of the master set and the terminal with each other. SOLUTION: An oscillation circuit 7 of a controller 2 in this interphone system always outputs an oscillation signal SIG2, whose frequency differs from a frequency of data communication signals SIG3, SIG4 that are sent/received from a call and a speech among terminals 3a-3c and a master set 1 to a trunk line L1, and the terminals and the master set detect presence/absence of the data signal SIG1 sent from its own device and the oscillation signal from the controller. If only the data signal is detected, broken trunk line is detected, and when only the oscillation signal is detected, a circuit fault is detected, and when the data signal and the oscillation signal cannot be detected, the short circuit of the trunk line can be detected. Thus, the system can properly cope with the fault and take quick processing, the efficiency of repair can be executed.
|
