When "L Run" Led Goes Off - Mitsubishi MELSEC-Q Series User Manual

6 TROUBLESHOOTING

6.4.2 When "L RUN" LED Goes Off

"L RUN" LED of remote
I/O station goes off
Has transmission speed
setting of master station been
changed after data link
communication?
NO (Not changed)
Any line problem? *1
NO (No problem)
Is station No.
setting normal? *2
YES
Is station No.
within masters control
range? *3
YES
Consult local servicing
company, dealer, or our
branch office.
*1: Check for short circuit, inverse connection, cable break, excessive pressure to a cable, terminating resistor,
overall extended length, drop line length (overall length, longest drop length) and peripheral environment
(such as noise).
*2: Pay attention to the following.
The station number should be neither 0 nor more than 64.
The number of units should be 0 to 9.
It should not be mistaken for the output hold setting switch or the response speed setting switch.
*3: Check that each number of all stations occupied by the module is 64 or less, and they are within the control range
of the master station. (See Sec. 3.4.2, 3.5.)
*4: If the station number setting of a remote I/O station has been changed, turn the power of the entire system OFF and
then ON.
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YES (Changed)
Turn the system power
ON from OFF
YES (Problem identified)
Correct communication
cable wiring
NO
Set station No. correctly *4
NO
Set station No. within
masters control range. *4
END
MELSEC-Q
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