Udp/Ip Communications; Communication Process - Mitsubishi Electric MELSEC-L SERIES Basic User Manual

● Change connection settings before executing the OPEN instruction.
● Once an open process is performed, an open request cannot be canceled before the open process is completed.
Perform a close process (Execute the CLOSE instruction) after the open process is completed.
7.3

UDP/IP Communications

This section describes UDP/IP communications. In UDP/IP communications, the system does not establish a
connection and does not check whether each data has arrived at the destination normally, thereby reducing the load
on the line. However, UDP/IP communications do not guarantee data reliability as the TCP/IP communications do.
7.3.1

Communication process

Unlike TCP/IP communications, UDP/IP communications do not require connections to be established with connected
devices.
The server requests
data reception and
reads the received data.
● If a timeout has occurred in the alive check function, the corresponding bit of Open completion signal (address: 5000
automatically turns off and the communication line is closed.
● After the connected device sends a close request to the E71, wait for 500ms or more before performing an open process
again.
Server
E71
Open
Data sending
Receive process (reading)
Data sending
Data sending request
Close
CHAPTER 7 COMMUNICATION PROCEDURE
Client
Connected device
The client opens
Open
the port.
The client specifies
Data sending request
the destination and
sends data to it.
Receive process (reading)
Close The client performs
the close process.
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