Mitsubishi Electric MELSEC-L Series - UDP;IP Communications; Communication Process

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CHAPTER 7 COMMUNICATION PROCEDURE
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7.3 UDP/IP Communications 7.3.1 Communication process
● 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.
● If a timeout has occurred in the alive check function, the corresponding bit of Open completion signal (address: 5000
H
)
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.
Connected device
E71
Server
Client
Open
Open
Receive process (reading)
Data sending request
Data sending
The client opens
the port.
The client specifies
the destination and
sends data to it.
CloseClose
Receive process (reading)
Data sending
Data sending request
The server requests
data reception and
reads the received data.
The client performs
the close process.