Passive Open Procedure; When "Do Not Open By Program" Is Set - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Passive open procedure

The following two types of connection methods can be used to Passive open the Ethernet-equipped module.
Connection Description
method
Unpassive This connection method executes a passive open processing for the connection to all devices connected to the network without restriction to
the IP address or port number of the communication destination.
Fullpassive When the IP address and port number of the communication destination are specified, this connection method executes a passive open
processing for the connection of the specific external device.
The open/close processing procedure for Passive open follows the setting of "Opening Method" under "Own Node Settings"
in "Basic Settings". ( Page 242 Own Node Settings)

■When "Do Not Open by Program" is set

The Ethernet-equipped module is constantly in the open standby state, so the connection is established when Active open is
initiated by the external device. This eliminates the need for an open/close processing program on the Ethernet-equipped
module side.
Ex.
Open/close processing for connection No.1
Open status
Open enable status (closed)
(Active open acceptance enabled)
Closed status
'Initial status' (Un\G1900024.0)
'Open completion signal
(connection No.1)'
(Un\G1900000.0)
'Open request signal
(connection No.1)'
(Un\G1900008.0)
 After the module parameters are set, checks that the initial processing for the Ethernet-equipped module has completed normally. ('Initial status'
(Un\G1900024.0): On) When the initial processing completes normally, the connection enters the open enable state, and the module waits for the open
request from the external device.
 The Ethernet-equipped module executes the open processing when an open request (SYN) is received from the external device. When the open processing
ends normally, 'Open completion signal (connection No.1)' (Un\G1900000.0) turns on and data communication is enabled.
 The Ethernet-equipped module executes the close processing when the close request (FIN) is received from the external device. When the close
processing completes normally, the open completion signal turns off and data communication is disabled.
 After the internal processing in the Ethernet-equipped module completes, the connection stands by for the open request again.
*1 The open request (SYN) received between the initial processing normal completion to the open request standby state is handled as an
error, and the Ethernet-equipped module sends a connection forced close (RST) (to the external device that sent the open request
(SYN)).
When the open/close processing is executed with a dedicated instruction from the Ethernet-equipped module,
even if "Do Not Open by Program" is set in "Opening Method" under "Own Node Settings" in "Basic Settings",
the connection will not return to the open request standby state after the close processing completes.
Parameter
communications
completed
Power-on
Ò
*1
SYN
SYN + ACK
Ó
ACK
Appendix 5 TCP/IP Communications, UDP/IP Communications
Õ
FIN + ACK
Ô
FIN
ACK
APPX
A
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