Passive Open Processing/Close Processing - Mitsubishi MELSEC-F User Manual

5 COMMUNICATION PROCEDURE

5.6.2 Passive open processing/close processing

Open status
Open allowed status
(Active open acknowledge
enabled)
Close status
Initial normal completion
BFM#27="0001 "
H
Open completion signal
BFM#20480
Open allowed status
BFM#20482
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This section explains the procedure for opening and closing a connection with the
Ethernet module via an external device.
The operations of Passive open processing/close processing differ depending on
whether "Always wait for OPEN" or "Do not wait for OPEN" is selected, as shown in
this section.
(1) When "Always wait for OPEN" is selected in the operational setting
This is an explanation of (BFM #24 b8: ON) open processing/close processing
when initial timing settings for Operational Settings are set to be always wait
OPEN (Communication Possible at STOP).
In this case, sequence programs for open processing and close processing are
not required because the Ethernet module keeps the connection in the always
wait for the OPEN status according to the [Open settings] parameter setting.
For detail on the [Open settings] parameter, see Section 5.5, "Open Settings".
Parameter
communication
completed 1)
Power-on
1 An open request (SYN) received after the normal completion of an
initial processing and before the Ethernet module is placed in the open
acknowledge enabled status generates an error, and the Ethernet
module sends a connection forced close (RST).
( *1 )
SYN + ACK
2)
SYN
MELSEC-F
4)
FIN + ACK
3)
FIN
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