| 摘要 |
PURPOSE:To prevent the whole system from being shut down by placing a time- division type transmission module in reception mode except in a transmission time all the time and sending back a confirmation answer at intervals of data transfer between stations. CONSTITUTION:If the transmission line 3 between a repeater station 20b and a receiving station 20c is broken at 24 or if the transmission module 21c of the receiving station 20c enters a shutdown state, the repeater station 20b waits for an answer for a specific time and judges that abnormality occurs between the repeater station 20b and receiving station 20c unless a received answer signal is returned. Then, the transmission module 21b is placed in transmission mode and down information is sent to a transmitting station 20a. The transmitting station 20a receives the information, which reaches the repeater station 20b through the transmission module 22a, so that a confirmation answer signal to the down information is sent out. Then, the transmission module 21a is placed in transmission mode and sent data is returned in the opposite direction. |
