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MELSEC-Q
11 TROUBLESHOOTING
Protocol
Error code
(Hexa-
decimal)
Error
Description
Signal
name
Corrective action
MC
Non
Proce-
dure
Bidire-
ctional
Pre-
defined
Error count error
• Number of requested points exceeds
the range for the command.
• Check and correct the external device
transmit message and restart data
communications.
7E42H
Protocol setting data
write error
• Protocol setting data were written to the
Q series C24 that does not support the
pre-defined protocol communication.
PRO
• To use the pre-defined protocol
function, use a supported Q series
C24N. (Use the QJ71C24N(-R2/4)
whose first 5 digits of serial No. is
10122 or higher.)
7E43H Device error
• A nonexistent device was designated.
• Device that cannot be specified by the
corresponding command was
designated.
• The head device No. is out of range.
PRO
• Check and correct the external device
transmit message and restart data
communications.
7E44H
Timer 1 time-out
error
• A response message was not returned
within the response monitoring time
(timer 1) monitoring time.
C/N
• Make the timer 1 monitoring time
longer.
• When accessing another station's CPU,
check if the routing parameters match.
7E46H System error
• The OS of the Q series C24 detected
some error.
⎯ (1)
7E47H
Continuous request
error
• The next request was received before a
response message was returned for the
preceding request.
PRO
• Do not issue continuous requests from
the external device.
• Set the timer 1 monitoring time to the
external device time-out time.
7E48H
to
7E4C
H
System error
• The OS of the Q series C24 detected
some error.
⎯ (
1)
7E4DH
Error during data
transmission
• Mode switching was executed during
data transmission.
CHn
ERR.
• Make arrangements between the target
device and programmable controller
CPU so that mode switching is not
executed during data transmission.
7E4EH System error
• The OS of the Q series C24 detected
some error.
⎯ (1)
7E4FH
Device point count
error
• Access point count is incorrect. PRO
• Check and correct the external device
transmit message and restart data
communications.
7E50H
User frame No.
designation error
• A user frame No. outside the range was
designated.
PRO
• Check and correct the external device
transmit message and restart data
communications.
• Recheck the frame No..
7E51H
Unwritten user
frame error
• An unwritten user frame No. was
designated.
PRO
• Write the frame beforehand.
• Change the frame No. and restart data
communications.
• Recheck the frame No..
7E52H
User frame
overwrite error
• A written frame No. overwrite request
was issued.
PRO
• Change the write destination to an
unwritten frame No.
• When overwriting, delete the given No.
beforehand.
7E53H
User frame access
data error
• A nonexistent command was
designated in a subcommand.
• Byte count exceeding the number of
bytes that can be requested was
designated.
PRO
• Check and correct the external device
transmit message and restart data
communications.
7E54H
Modification allowed
error
• Flash ROM write allow/prohibit
designation from GX Configurator-SC is
set to OFF.
• At the switch setting on GX Developer,
modification allowed switch was set to
OFF.
PRO
• Set to ON at GX Configurator-SC.
• Set to ON at GX Developer.
7E55H
User frame data
error
• There is an error in the user frame
variable data.
PRO
• Check and correct the external device
transmit message and restart data
communications.
7E56H System error
• The OS of the Q series C24 detected
some error.
⎯ (1)
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