Mitsubishi QJ71LP21 Reference Manual page 235

8 TROUBLESHOOTING
8.2.8 Checking for incorrect fiber-optic cable connection during online
Start
Check the loopback information
(SW90) of the host station.
Are the loops normal?
(Is the SW90 value 0?)
Yes (0)
Check the loop using status of each
station (SW9C to SW9F).
Are all bits of SW9C to
SW9F OFF or ON?
Yes
The cables are connected normally
to all stations.
End
8 - 24
This section explains the checking procedure for incorrect fiber-optic cable connection
(IN-IN, OUT-OUT) during online and the link special registers (SW009C to SW009F)
used for the check.
Unlike the loop test, the checking procedure given in this section allows a check
without stopping a data link.
If incorrect cable connection is found, correct the wiring after shutting off all phases of
the system.
POINT
Before starting the check given in this section, make sure that the following
conditions are satisfied.
If these are not satisfied, conduct a loop test to make a check.
The fiber-optic cables have no breaks. (Both the forward and reverse loop cables
are normal.)
There are no stations having data link error (power off, MELSECNET/H module
failure).
(1) Checking procedure
Follow the procedure given below to check for incorrect fiber-optic cable
connection (IN-IN, OUT-OUT) during online.
No
(Other than 0)
No
Conduct a loop test to identify the faulty portion, and change the cable.
1) The bit of only one station is ON or OFF.
<Cause>
The cable of the station whose bit is ON is incorrectly connected
(IN-IN, OUT-OUT).
<Corrective action>
Check the cable connection status of the station whose bit is ON.
2) The bits of multiple stations are ON or OFF.
<Cause>
The cables of the stations whose bits are ON are incorrectly
connected (IN-IN, OUT-OUT).
<Corrective action>
Check the cable connection status of the stations whose bits are ON.
3) The bits of all stations except for the host station are ON or OFF.
<Cause>
The cable of the host station is incorrectly connected
(IN-IN, OUT-OUT).
<Corrective action>
Check the cable connection status of the host station.
MELSEC-Q
8 - 24