When Data Link Is Disabled Because Of Reset Or Power Off Of Each Station; When A Specific-Station's Data Link Cannot Be Executed - Mitsubishi Electric QJ71LP21 Reference Manual

8 TROUBLESHOOTING

8.2.3 When data link is disabled because of reset or power off of each station

Check item
Is the cable wired properly?
Are the cables disconnected?
Are the switches of the network modules on all
stations set in the correct position?
Is the setting of the link monitoring time sufficient?

8.2.4 When a specific-station's data link cannot be executed

Check item
Monitor the transmission status of each station.
Is the network module of the faulty station normal?
Was the loop error caused by the network module
or the data link cable?
Are the remote master station's parameters
correct?
Are the control station's parameters normal?
Are the switch settings of the network module
correct?
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Check the wiring status with GX Developer's network diagnostic loop test.
(See Section 4.10.1.)
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.
Make sure that the mode setting switches of the network modules on all stations are in
the same position.
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.
POINT
Do not reset stations which are adjacent each other in a light loop system (adjacent
stations on the wire) simultaneously (resetting by the reset switch of the remote I/O
station or resetting by the key switches of the PLC CPUs of the remote master
station and remote sub-master station). Otherwise, data link may not be able to be
established.
If initialization and so on is necessary on adjacent stations simultaneously, turn off
and on the power supply.
Perform line monitoring of the network diagnostics of GX Developer, check for any
abnormally communicating station and check the loop status. Also, check whether or
not data linking is stopped.
In case of an optical loop system, check the line condition and transmission status of
each station as well, using the loop test of GX Developer's network diagnostics.
Check whether or not an error or problem occurred in the CPU module and network
module of the faulty station.
Check whether or not the network module works normally with the self-loopback test of
the offline tests.
Check whether or not the data link cable is normal with the loop test of the offline tests.
Check that the total number of link stations is set to the largest number of the
connected stations or more, and check that the stations that cannot communicate are
designated as reserved stations.
Read the network parameters from the faulty station's CPU module and check that the
network settings such as the network type, start I/O number and network number are
correct.
Check the station number setting switch and the mode setting switch.
Checking procedure
Checking procedure
MELSEC-Q
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