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MELSEC-Q
11 TROUBLESHOOTING
11 TROUBLESHOOTING
This chapter explains the error details and corrective actions.
11.1 Troubleshooting
(1) Troubleshooting of errors indicated by LEDs
No.
Symptom
Check Item
Corrective Action
Reference
Section
Check the mounting status of the
QJ71MT91.
Switch the power off and remount the
QJ71MT91.
Section 6.1
Check the power supply capacity.
Change the power supply module.
Section 3.1
Check the programmable controller
CPU.
If the programmable controller CPU is
faulty, take corrective action according
to the QCPU User's Manual (Hardware
Design, Maintenance and Inspection).
1 RUN LED turned
off.
Check for a watch dog timer error (X1F). • Reset the programmable controller
CPU or power the programmable
controller off and then on.
• If the problem still persists after
resetting it again, the possible cause is
a hardware fault. Perform a hardware
test, and replace the QJ71MT91.
Check the intelligent function module
switch 1 (operation mode setting) value.
Check the intelligent function module
switch 2 (communication condition
setting) value.
Check the intelligent function module
switch 3, 4 (IP address setting) value.
Check the setting range of each
intelligent function module switch, and
correct the value.
Section 6.6
Check if the QJ71MT91 is not mounted
with the A mode QCPU.
Mount the QJ71MT91 with the Q mode
QCPU.
Section 2.1
Check if the module is in the hardware
or self-loopback test mode.
• Restart the test after checking the
mounting status of the QJ71MT91.
• If the ERR. LED turns on again, the
possible cause is a hardware fault.
Change the QJ71MT91.
Section 6.5.1
Section 6.5.2
2 ERR. LED turned
on.
Refer to "RUN LED turned off."
This section
(1)-1
Check if the basic parameter setting,
error completed (X2) is on.
Refer to "Basic parameter setting, error
completed (X2) turned on."
This section
(2)-3
3 COM.
ERR.
LED
turned on.
Check if the automatic communication
parameter setting, error completed (X5)
is on.
Refer to "Automatic communication
parameter setting, error completed (X5)
turned on."
This section
(2)-5
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