Chapter 7. Maintenance and Inspections
7.3 Loop-back
check
Run a loop-back check in accordance with the procedure explained below when normal operations are not
possible during test operations of the link system, and when errors occur after start-up, resulting in link
system operations being suspended. Note that link system operations must be suspended before the
loop-back check can be run. The cable used for the loop-back check must be prepared by the user.
1 ) Set the station No. setting switch on the optical link module to be checked at "90".
2 ) Connect the loop-back check cable.
Table 7.1 Loop-back check preparations
3 ) Switch on the power supply, and then switch the reset switch from ON to OFF while pressing the link
module's error display clearance switch. The RUN LED will blink twice if the loop-back check mode has
started up normally.
4 ) The link module's RUN LED and ERR LED will change as follows.
Abnormal
RUN LED lighting (1 s)
ERR LED lighting (1 s)
Normal
Check end
LED Lights-out
Check start
RUN LED 2 times blinking
Figure 7.2 Loop-back check operations
* Contact our service department if an error is detected.
7-2
