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MELSEC-F
COMMUNICATION PROCEDURE5
5 - 34
1) After the parameters are sent, the normal completion of the Ethernet
module initial processing is confirmed (Initial normal completion signal
BFM#27 "0001
H")
After the initial processing is normally completed, the connection is
placed in the open allowed status and the Ethernet module waits for an
open request from the external device.
2) The Ethernet module starts the open processing upon receiving the open
request (SYN) from the external device.
When the open processing is normally completed (Open/close status
(BFM#1602 "0005
H")), the open completion signal (BFM#20480 b0) turns
on and data communication is enabled.
3) The Ethernet module starts the close processing upon receiving the
close request (FIN) from the external device.
When the close processing is completed (BFM#1602 "0000
H"), the open
completion signal (BFM#20480 b0) turns off and data communication is
disabled.
4) After the Ethernet module's internal processing is Rissn/completed, the
connection returns to the open acknowledge enabled status.
NOTE
For Passive open connections for which [Always wait for OPEN (Communication
possible at STOP time)] is selected in [Operational settings], the connection open/
close processing of the Ethernet module side is performed according to the open/
close request from the external device.
When the close processing is performed from the Ethernet module (this station), the
applicable connection will not return to the open acknowledge enabled status after
the close processing, even if [Always wait for OPEN (communication possible at
STOP time)] is selected in [Operational settings].
(It requires the same open processing and close processing as the connection for
Passive open for which [Do not wait for OPEN (communication impossible at STOP)]
is selected.)
(2) When "Do not wait for OPEN" is selected in the operational setting
When initial timing settings of operational settings are at [Do not wait for OPEN
(communication impossible at STOP time)], the (BFM #24 b8: OFF) open
processing/close processing is performed as explained below.
Since open processing/close processing is executed by a sequence program, an
external device can be changed while the connection is established.