| 摘要 |
PROBLEM TO BE SOLVED: To improve the communication quality of a conventional data communication node device having only one set of transmission lines for two-way communication with a simple control method by realizing a function, which remedies communication troubles caused by the fault of an interface by switching the faulty interface to a standby interface by such a simple control means that the setting of a switch is changed and the transmission from the interface is stopped when the fault is detected. SOLUTION: An interface 1 which is operated as an active system and another interface 2 which is operated as a standby system are connected two- way to each other for communication. The interfaces 1 and 3 are connected to an optical transmission line 5 via an optical coupler 4, in a state where signals are transmitted only from the interface 1 and no signal is transmitted from the interface 3. During normal operation, the data transmitted to the opposite-side device 6 via the line 5 are transferred to the interface 1 from a switch section 7. When a fault occurs in the interface 1, the switch section 7 switches the destination of the signal to the interface 3 from the interface 1. |
