Passive Open Procedure - Mitsubishi Melsec-L Series User Manual

7.2.4

Passive open procedure

The E71 has the following two connection methods for Passive open.
• Unpassive:
• Fullpassive:
Under the Passive open method, the open/close processes are performed using the procedures described below,
according to the Ethernet operation setting.
(1) When "Always wait for OPEN (Communication possible at STOP time)" is
selected for the Ethernet operation setting
As the E71 is set to always wait for open, a connection is established when an Active open is requested from the
connected device. This eliminates the need for open/close processing programs on the E71 side.
Open status
Open allowed status (closed)
(Active open acceptance enabled)
Closed status
Initial normal completion
signal X19
Open completion signal
(address: 5000
Open request signal
(address: 5002
After parameter communications, check that the initial process of the E71 is normally completed.
1
(Initial normal completion signal (X19): ON)
After the initial process is normally completed, the connection enters open enable status and the E71 waits for an
open request from the connected device.
The E71 starts the open process upon receiving the open request (SYN) from the connected device. When the
2
open process is normally completed, Open completion signal (address: 5000
communications are enabled.
The E71 starts the close process upon receiving the close request (FIN) from the connected device. When the
3
close process is completed, Open completion signal (address: 5000
disabled.
After the internal process of the E71 is completed, the connection returns to the OPEN request wait status.
4
*1 An open request (SYN) received after the normal completion of an initial process and before the E71 is in the OPEN
request wait status will cause an error, and the E71 sends a connection forced close (RST).
Performs a passive open process on connections for all devices connected to the network,
regardless of the IP address and port number of the destination device.
Performs a passive open process on connections for the connected device specified by the IP
address and port number.
Parameter
communication
Power-on completed
1
)
H
)
H
CHAPTER 7 COMMUNICATION PROCEDURE
*1
SYN + ACK
2
SYN
ACK
H
(b0)) turns off and data communications are
H
4
FIN + ACK
3
FIN
ACK
(b0)) turns on and data
7
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