Active Open Procedure - Mitsubishi Electric MELSEC-L SERIES Basic User Manual

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