| 摘要 |
PURPOSE:To prevent malfunction such as starting of a fixed connecting line in error, by providing countermeasures for the fixed connecting line connected via a data transmission line against a failure of the transmission line. CONSTITUTION:A control signal transmitted from a telephone set S of the fixed connecting line is outputted to a backward highway HWB2 from a transmission circuit SE with multiplexing together with control signals of the other fixed connecting lines via the fixed connecting line set in a channel device TDSW. If a failure takes place in a digital signal transmission line DL, alarm goes, an output at a terminal ALM goes from ''0'' to ''1'' to turn on an SCN signal forcedly. A selector SEL is changed over with the output change of the ALM, the transmission of a signal processor SP1 to a forward highway (for fixed connecting) HWF2 is blocked and the corresponding data is read out from a failure data memory FD-MEM and transmitted instead. |
