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11
TROUBLESHOOTING
No.
Symptom
3
Slave function of
QJ71MT91 does
not return
response
message to
request message.
4
GX Developer
cannot be
connected.
5
Error log has
errors.
11 - 8
Check Item
Check if the INIT. LED is on.
Check if the MODBUS device
assignment parameter setting existence
(XA) is on.
Check whether the basic parameters
were re-set during reception of a request
message.
(The slave function stops when the basic
parameters are re-set.)
Check whether the QJ71MT91 has
returned an exception code or not.
Refer to the error log area (0CFE
0DFF
) and confirm the error code.
H
Is the request message sent to the
QJ71MT91 correct?
Check the following for the message
length.
• The application data unit length in
Ethernet frame is 6 or more (From
"Transaction ID" to "Message length"
in MBAP header).
• The MBAP header length + 6 equals
the application data unit length in
Ethernet frame.
Refer to "Communication with target device cannot be made even though each
parameter setting is completed.".
Check if the INIT. LED is on.
When using the TCP protocol, check
whether the set number of TCP
connections for GX Developer
connection is 0 or not.
Check the GX Developer connection
setup screen settings.
Refer to "Communication with target device cannot be made even though each
parameter setting is completed.".
Refer to the error log area (0CFE
0DFF
) and confirm the error code.
H
Refer to "Communication with target device cannot be made even though each
parameter setting is completed.".
Corrective Action
Refer to "INIT. LED does not turn on.".
Refer to "MODBUS device assignment
parameter setting existence (XA) does
not turn on.".
Restart the automatic communication
function after basic parameter re-setting
is completed.
Confirm the exception code and take
corrective action.
to
Take the corresponding corrective
H
action.
Correct the request message issued by
the master.
Refer to "INIT. LED does not turn on.".
Set the necessary number of TCP
connections for GX Developer
connection (0030
parameter.
Correct the GX Developer connection
setup screen settings if it has a problem.
to
Take the corresponding corrective
H
action.
MELSEC-Q
Section 11.3.2
), and re-set the basic
H
Reference
Section
This section
(1)-4
This section
(2)-11
Section 7.2
Section 11.3
Chapter 4
This section
(3)-6
This section
(1)-4
Section 7.2.3
This section
(3)-6
Section 11.3
This section
(3)-6
11 - 8
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