Items To Be Checked First; When Data Link Cannot Be Executed On The Entire System - Mitsubishi Electric QJ71LP21 Reference Manual

8 TROUBLESHOOTING

8.2.1 Items to be checked first

Check item
Monitor the transmission status of each station
with GX Developer 's network monitor.
Is the "RUN" LED of the CPU module on?
Are LEDs of the network module operating
normally?
Are the "RUN," "REM.," "T.PASS," and "D.LINK"
LEDs of the remote I/O module on?
Are the "ERR.," and "L ERR" LEDs OFF?
Are "RUN", "REM." LEDs on the remote I/O
module on?
Has the error reset process using SM50/SD50
been performed after the online module change
function was executed on a remote I/O station?
Are the ERR contacts of the power supply
modules of the master station and remote I/O
station ON?

8.2.2 When data link cannot be executed on the entire system

Check item
Monitor the communication status of each station
with GX Developer's network diagnostics.
Are the network parameters set for the remote
master station?
Are the switch settings of the remote master
station's network module correct?
Are the switches of the network modules on all
stations set in the correct position?
Is the link monitoring time set to a sufficient value?
Did the remote master station go down?
8 - 19
Check the CPU module status of the faulty station, the status of the network modules,
the loop status of each station to search for the location where the error occurred.
If the "RUN" LED is off or flashes, read the error code with GX Developer and correct
the error. (For details on error handling, refer to the CPU module's User's Manual
(Hardware Design, Maintenance and Inspection).)
Check the "RUN", "ERR", and "L ERR" LEDs and take the corrective action if any error
is found. (Refer to Section 4.2.)
If the "RUN," "REM.," "T.PASS," and "D.LINK" LEDs are OFF or the "ERR." and "L
ERR." LEDs are ON, diagnose the remote I/O module by GX Developer.
(See Section 4.2.)
If the "T. PASS", "L ERR." LED turns on and off improperly and looks instable, refer to
the following.
<Cause>
The line status is assumed to be instable.
<Troubleshooting>
1) Check the connector for loose connection and the cable for a break.
2) Check that the cable used conforms to the specifications.
3) Check that the overall length and interstation distance conform to the specifications.
(Refer to Section 4.8 Cable Connection.)
If the LEDs are out, use GX Developer to diagnose the remote I/O module.
Perform the error reset process by the procedure below after executing the online
module change function.
1) Perform the error reset process on the remote I/O station.
2) Perform the error reset process on the PLC CPU of the master station.
1) If the ERR contact of the power supply module of the master station is OFF, check
the status of the power supply connected to the power supply module of the master
station, or diagnose by GX Developer if a stop error has not occurred on the CPU
module of the master station.
2) If the ERR contact of the power supply module of a remote I/O station is OFF, check
the status of the power supply connected to the power supply module of the remote
I/O station, or diagnose by GX Developer if a stop error has not occurred on the
remote I/O module of the remote I/O station. However, the ERR contact of the power
supply module of the remote I/O station is turned off instantaneously when data link
parameters are received from the master station after the parameters of the remote
I/O station are changed. (The ERR contact is turned on when communication
becomes ready due to the reception of data link parameters.)
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.
Check whether the network parameters from the remote master station's CPU module
are set.
Check the station number setting switch and mode setting switch.
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 can be performed.
Check the on/off status of the LEDs of the network modules of the remote master
station.
Checking procedure
Checking procedure
MELSEC-Q
8 - 19