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11
TROUBLESHOOTING
No.
Symptom
6 Communication
with target device
cannot be made
even though each
parameter setting
is completed.
7 Communication
interval time with
the slave by the
automatic
communication
function is longer
than time set to
the repeat interval
timer.
Dedicated
instruction requires
a long time to be
completed.
8 QJ71MT91
responds slowly.
11 - 10
Check Item
Check if the total number of TCP
connections specified for use with
preferred nodes is within 64.
Check if linkup has performed to a hub. The automatic communication function
Check the target device.
• Check for errors.
• Check whether the target device is
ready for operation.
Check the line status.
Check for any TCP connection
disconnected automatically by the
KeepAlive function.
Check if the number of TCP connections
connected simultaneously is within 64.
Check whether the QJ71MT91 has
issued two or more send requests
concurrently.
Check whether the target device
requires a long time to respond.
Check the specifications using the
processing time performance expression
of the QJ71MT91 slave function.
Check whether the QJ71MT91 has
issued two or more send requests
concurrently.
Check the line status.
Corrective Action
As the connection resources are all
assigned to the preferred nodes, the
other nodes cannot communicate.
Delete the unnecessary preferred node
specifications.
is executed regardless of linkup status.
Take corrective action the either of
following:
• Start communications using a
sequence program after linkup. (Refer
to Section 9.2.3 (5)).
• Ignore errors if the own module is
communicating with the hub properly
after linkup.
Take corrective action if the target
device has any problem.
Correct the line status if it has any
problem in traffic.
• Check that the target device is
operating normally.
• Adjust the KeepAlive start timer value
and KeepAlive interval timer value.
• Retry as TCP connections may fail
temporarily.
• TCP connections with the nodes not
specified as preferred ones may be
closed automatically when the
connection resources become
insufficient. Specify the nodes as
preferred ones when necessary.
• Reduce the number of simultaneously
connected connections.
If two or more send requests are issued,
long time is required as they are
processed in due order. Reduce the
QJ71MT91 loads.
• Confirm the processing performance
of the target device.
• If the target device has any problem,
check and take corrective action.
Reduce the processing time to within the
range of the performance expression.
If two or more send requests are issued,
long time is required as they are
processed in due order. Reduce the
QJ71MT91 loads.
Correct the line status if it has any
problem in traffic.
MELSEC-Q
Reference
Section
Section 7.2
Section 5.2
Section 5.4
Section 7.2
Section 3.1
Section 7.2
Appendix 2
11 - 10
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