To obtain a short circuit detection method and a recovery method or the like for a transmission line by which a short circuit detection time is reduced and the short-circuit is recovered with a saved installation space at a reduced cost.
In a transmission system where data are transmitted through a control data signal transmission line LC by applying transmission voltage to the line LC, a speech controller control circuit section 101 configures polling data with the assistance of a section that holds the transmission voltage for a prescribed time without failure and transmits the data. The polling data transmitted through the control data signal transmission line LC are received to try to detect a transmission voltage applied to the control data signal transmission line LC on the basis of a predetermined threshold value. When it is discriminated that the transmission voltage is not detected, it is discriminated that the control data signal transmission line LC is short-circuited, and when it is discriminated that the transmission voltage is detected, it is discriminated that the control data signal transmission line LC is not short-circuited.
YAMAGISHI TAKATOSHI
TSUDA TAKASHI
