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MELSEC-Q
8 TROUBLESHOOTING
8.2.2 Data link failure on the entire system
Check item Checking procedure
Monitor the communication status of each station with GX
Developer's network diagnostics.
Check the line condition with GX Developer's network diagnostic loop test
(only in case of optical loop test).
Check the faulty station's CPU module and network module.
Check the network module and data link cable with the self-loopback test and
station-to-station test of the offline tests.
Check whether data linking is stopped for all stations.
Are the network parameters set for the control station?
Check whether the network parameters from the control station's CPU
module are set.
Are the switch settings of the control station's network
module correct?
Check the station number setting switches and mode setting switch.
1
Are the switches of the network modules on all stations set
in the correct position?
Make sure that the mode setting switches of the network modules on all
stations are in the same position.
1
Is the link monitoring time set to a sufficient value?
Set the link monitoring time to the maximum value and check whether or not
data linking can be performed.
Did the control station and remote master station go down?
Check the on/off status of the LEDs of the network modules of the control
station and the remote master station.
Did the control switch to the sub-control station?
Check that the "continue data linking by a sub-station when the control
station goes down" setting is set to "Yes" in the communication error settings
of the control station's common parameters.
1: For the QJ71NT11B, check the station number/mode setting switch.
8.2.3 Data link failure caused by reset or power-off of each station
Check item Checking procedure
Is the cable wired properly?
Check the wiring status with GX Developer's network diagnostic loop test.
(Refer to Section 4.8.1.)
Is the network cable disconnected?
Check the status of each station to see whether the entire system is faulty or
a specific-station is faulty, and locate the faulty area.
Are the switches of the network modules on all stations set
in the correct position?
Make sure that the mode setting switches of the network modules on all
stations are in the same position.
1
Is the setting of the link monitoring time sufficient?
Set the link monitoring time to the maximum value and check whether or not
data linking is possible. If the L ERR. LED of a normal station is lit, check the
TIME error with the GX Developer's network diagnostics.
1: For the QJ71NT11B, check the station number/mode setting switch.
POINT
In the optical loop system, do not reset the CPU modules of adjoining stations
(adjoining stations on the wiring) at the same time.
Data link may be disabled.
In the case of initializing adjoining stations at the same time, turn off the power and
turn it on again.
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