| 摘要 |
PURPOSE:To make backup of faulty units even if one or plural units out of multiplex communication units are faulty, by sharing only a synchronizing signal line with the synchronizing signal of another unit when a synchronizing signal generator is faulty. CONSTITUTION:If a synchronizing signal generator S1 is faulty, a changeover switch SW1 is switched to a synchronizing signal line 41 of the fourth communication unit U4. The synchronizing signal which is given to a synchronizing signal line 11 from a synchronizing signal generator S4 of the unit V4 is given to the synchronizing signal line 41 also. Consequently, transmitters T41 and T42 and receivers R41 and R42 of the unit U4 are operated simultaneously with the operation of a unit U1. Thus, switch operation information of an operation switch part 43 is transmitted and received through a data line 42 between the transmitter T41 and the receiver R41 and between the receiver R42 and the transmitter T42 when the synchronizing signal assigned to the unit U4 itself appears on the synchronizing signal line 41. That is, only the synchronizing signal from the synchronizing signal generator of another unit is borrowed merely to perform the backup operation for trouble.
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