Mitsubishi Melsec-L Series User Manual page 76

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
*1 If the E71 sends an SYN and the connected device returns a RST, Open abnormal detection signal (X18) turns on
immediately and the open process terminates. (Open abnormal end)
*2 If an ACK and a FIN are not returned within the time specified by the TCP end timer value, the E71 forcibly closes the
connection (sends a RST). (Close abnormal end)
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(b0)): ON)
H
*1
*2