| 摘要 |
PURPOSE:To miniaturize a transmitter that includes a switch by exercising switching control in response to an alarm received from a terminal equipment. CONSTITUTION:When A circuit 20 is cut off, terminal equipments 21 and 24 send alarm signals to alarm receiving terminals 12 and 16 of circuit switches 25 and 26 as earth signals. In response to those alarm signals, logic circuits 13 and 17 of both the switches operate relays 14 and 18 to switch relay contacts 15 and 19. Consequently, A circuit 20 is changed over to B circuit 22. By the ceasing of alarm signals generated by terminal equipments 21 and 24, it can be made sure that the switching of both stations 25 and 26 is completed and a normal transmission line is constituted. |
