Message Communication Function (Client) - Mitsubishi Electric MELSEC iQ-R Series User Manual

12.3

Message Communication Function (Client)

Function overview
This function performs Explicit message communications point-to-point between the client (message sending side) and the
server (message receiving and processing side).
Client
The available functions include the general message communications client function for sending data at any timing by using
message communication support commands and the tag communications client function for periodically reading/writing data
for the tag set to the server.
However, if the external device does not support the specified command request or tag communications, an error response is
returned.
• Explicit message communications are in accordance with the communications defined in the EtherNet/IP
specification.
• To use the message communication function (client), set Not 0 (start request) for 'EtherNet/IP
communication start request' (Un\G7340096) so that EtherNet/IP communications can be used.
• For details on the message communication support commands, refer to the following.
Page 349 MESSAGE COMMUNICATION SUPPORT COMMANDS
The message communication function (client) has the following communication methods.
Communication
method
UCMM message
communications
Class3 message
communications
UCMM tag communications
Class3 tag communications
■Message communications
UCMM (Unconnected) and Class3 (Connected) message communications are supported. Messages can be sent to the
server.
Data and parameters of the external device can be read/written according to the command request set in the sent message.
■Tag communications
UCMM (Unconnected) and Class3 (Connected) message communications are supported. Read/write requests can be sent to
the tag set to the server.
In tag communications, the request-sending side is called "Originator" and the request-receiving side is called "Target".
To use tag communications, the target side must support the tag communications server function.
The following table shows the processing for command requests sent by the originator.
Type
Originator (client)
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12.3 Message Communication Function (Client)
Command request
Command response
Connection Explicit message
setting method
No Buffer memory
Yes "EtherNet/IP
Configuration"
No Buffer memory
Yes "EtherNet/IP
Configuration"
Description
Read Send a Read request to the tag of the external device, and read data in the 'Class3/UCMM data area (tag
communications)' (Un\G8278016 to Un\G8462847) associated with the tag.
Write Send a Write request to the tag of the external device, and write data to the 'Class3/UCMM data area (tag
communications)' (Un\G8278016 to Un\G8462847) associated with the tag.
Server
Description Application
A function for Used when sending a message as needed.
performing message
communications for the
Used when sending a message periodically for such
server
purposes as monitoring.
A function for reading Used when the communication method is Unconnected
from/writing to the and when reading/writing the value of the device with a
server device by using priority lower than Class1.
the tag name
Used when the communication method is Connected
and when reading/writing the value of the device with a
priority lower than Class1.