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CHAPTER 7 COMMUNICATION PROCEDURE
7
7.2 TCP/IP Communications
7.2.3 Active open procedure
7.2.3 Active open procedure
Active open is a connection method that performs an active open process on a connected device in Passive open wait
status. The procedure that the E71 performs an Active open process is as follows. For the OPEN/CLOSE instructions,
refer to "DEDICATED INSTRUCTIONS". ( Page 196, CHAPTER 15)
Open/close processes for the connection number 1
After parameter communications, check that the initial process of the E71 is normally completed.
(Initial normal completion signal (X19): ON)
Start the open process using the OPEN instruction. (Open request signal (address: 5002
H
(b0)): ON)
The E71 performs the open process. (The E71 sends an open request (SYN) to the connected device.)
When the open process is normally completed, data communications are enabled.
*1
Start a close process using the CLOSE instruction. (Open request signal: OFF)
The E71 performs the close process. (The E71 sends a close request (FIN) to the connected device.)
When the close process is normally completed, data communications terminate.
*2
3
4
6
7
5
2
1
Open status
Open allowed status
(closed)
Closed status
Initial normal completion
signal X19
OPEN instruction
OPEN instruction
completion device
OPEN instruction
completion device + 1
CLOSE instruction
completion device
CLOSE instruction
completion device + 1
Open completion signal
(address: 5000
H
)
Power-on
Parameter communication
completed
1 scan
1 scan
FIN
SYN
SYN + ACK
FIN + ACK
CLOSE instruction
Open abnormal detection
signal X18
Open request signal
(address: 5002
H
)
ACK
ACK
Abnormally ended
Abnormally
ended
Abnormally ended
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