Udp/Ip Communications; Open Procedure - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

UDP/IP communications

This section describes the UDP/IP communications. Since UDP/IP communications does not establish a connection during
communication and does not check that the communication destination has correctly received the data, the line load is lower.
Note that the data reliability is lower than TCP/IP communications.
Communication flow
UDP/IP communications does not require a process to establish a connection with the external device as is required with
TCP/IP communications.
Ethernet-equipped module
The server requests
Receive processing (reading)
data reception and
reads the received data.
Data sending request
Wait at least 500ms or more before executing the open processing again after the close request is sent from
the external device to the Ethernet-equipped module.

Open procedure

The open/close processing procedure is as follows, according to 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
After the Ethernet-equipped module mounted station starts up, the UDP/IP communications setting connection automatically
opens, and data send/receive is enabled. Program for open/close processing is not required.
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 open/close processing after a connection with the external device is established must be executed by the
program.
Server
Open
Data sending
Data sending
Close
Client
External device
The client opens
Open
the port.
The client specifies
Data sending request
the destination and
sends data to it.
Receive processing (reading)
The client performs
Close
the close processing.
Appendix 5 TCP/IP Communications, UDP/IP Communications
A
APPX
383