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11
TROUBLESHOOTING
Error
Error Name
Code
Error during
73D7
close
H
processing
73D8
H
Open failure
73D9
H
Alive check
failure
73DA
H
(KeepAlive
function)
Target device
7400
H
port No. error
Target device
7401
IP address
H
error
7402
Open failure
H
7403
Send error
H
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Description
Transmission through the
connection being closed was
attempted.
Failed to open the TCP
connection for the request
message transmission.
Since the normal connection
resources were all being used,
a new TCP connection could
not be opened.
Since the existence of the
target device could not be
confirmed by the KeepAlive
function, the TCP connection
was disconnected.
The port number setting of the
target device is erroneous.
The IP address setting of the
target device is erroneous.
A TCP connection was not
established in the open
processing.
A send error occurred.
Lit LED
Corrective Action
• Retry after a little while.
• If this error occurs at execution
of the dedicated instruction, set
"TCP connection is not closed
COM.ERR.
after instruction completion" in
the close option of the control
data.
• Check whether the operation
status of the target device is
normal or not.
• Check the open status of the
target device.
COM.ERR.
• Review the IP address, port No.
setting and other parameters of
the target device.
• Check the line status for an
error.
• Retry after a little while.
• Decrease the number of TCP
COM.ERR.
connections used
simultaneously.
• Check whether the operation
status of the target device is
normal or not.
COM.ERR.
• Check the line status for an
error.
Review the port number setting
of the target device at the time of
COM.ERR.
transmission.
Review the IP address setting of
the target device at the time of
COM.ERR.
transmission.
• Check whether the operation
status of the target device is
normal or not.
• Check the open status of the
target device.
COM.ERR.
• Review the IP address, port No.
setting and other parameters of
the target device.
• Check the line status for an
error.
• Check whether the operation
status of the target device is
normal or not.
• Check the line status for an
COM.ERR.
error.
• As the line may be busy, retry
after a little while.
• Hardware fault.
MELSEC-Q
Occurrence
1)
2)
3)
4)
(Continued on next page)
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5)
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