PURPOSE: To speedily detect and cope with a problem part at a master station, and to improve a fault erasing capability by actively transmitting transmission abnormality detection data from a state which detects the transmission abnormality of a transmission line to both the master station and a s lave station.
CONSTITUTION: When an X-point line disconnection is generated between a master station A11 and a master station B12, the master station A11 detects the line disconnection, prepares line disconnection detection data UI, and transmits the data UI. A slave station (1) 14 receives the line disconnection detection data UI from the master station A11, transmits the data UI to a slave station (2) 15, the slave station(2) 15 transmits the data UI to a slave station(3) 16, and the slave station (3) 16 transmits the data UI to the master station A11 and the master station B12. In this case, each slave station (1)-(3) respectively transmit detection data UI1, UI2, and UI3 for the X-point line disconnection. The master station B receives those UI and UI1-3 detection data, analyzes the content, and switches a line switching device 13 which is set to the master A side, to the master B side. Thus, an operation at a waiting system can be started, and the line disconnection of the transmission line can be erased.
WATANABE TAKESHI
MORIYAMA YUTAKA
AKEDA YOSHIYUKI
