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MELSEC-F
TROUBLESHOOTING
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11.5.3 Errors in communication using MC protocol
Communication error
Check the open status of the
connection with the external device.
Are the corres-
ponding connection LEDs
(C1-C8) lit?
NO
YES
Was a command sent
form the external device?
NO
YES
Send the command to the Ethernet
module.
Was a response
returned to the device that sent
the command?
NO
YES
YES
1)
Execute the open processing of the
applicable connection. (For details,
see Section 5.6.)
Is the IP address
designation of the command
correct?
NO
YES
Correct the IP address and send
the command again.
NO
YES
Match the communication protocol
(TCP/UDP) with the external device.
(For details, see Section 5.5.)
Is the end code of
the response "0"?
NO
Fix the faulty part according to
the description of the end and
abnormalcodes (see Section 11.4).
Does the
communication protocol
(TCP/UDP) match with that of the
external device?
The command may not be sent to the
Ethernet module from the external
device on the command sending
side. Check the sending side.