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MELSEC-F
COMMUNICATION PROCEDURE5
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1) The open request signal turns off by writing "8000
H" to the BFM#1602.
2) The Ethernet module executes the close processing.
3) The Ethernet module sends a FIN request to the external device.
4) The external device sends back FIN and ACK messages in reply to the
FIN request sent by the Ethernet module.
(When the reply is not returned, the Ethernet module sends the FIN
request again.)
5) The Ethernet module waits for the external device to send an ACK and a
FIN.
(The module waits for the amount of time set in the TCP end timer value.
For details on how to set it, see Section 5.2, "Initial Settings".)
If the ACK and FIN messages are received at this point, it returns an ACK
as in the normal processing.
6) If an ACK and a FIN are not received within the time designated by the
TCP end timer, an RST message is sent to the external device.
7) The Ethernet module determines that the close procedure is completed
and turns off the open completion signal regardless of the status of the
external device.
NOTE
(1) When the procedure above is performed, the Ethernet module determines that
the closing of the external device is executed normally, thus the close
processing result is not stored in the error log area.
(2) The procedure described above is a special function of the Ethernet module; it
is not available for general TCP/IP protocols.