Mitsubishi Electric MELSEC iQ-R Series User Manual page 292

Operation when a command is accepted
When a Read/Write request is received from the client for the tag of the own station, and a tag with the same name as the tag
name set to the own station exists, read or write is performed on the buffer memory area assigned to that tag in 'Class3/
UCMM data area (tag communications)' (Un\G8278016 to Un\G8462847).
• To set a tag to the own station, set it in "EtherNet/IP Configuration". ( Page 117 Parameter settings for
EtherNet/IP devices)
• The target tag must be a Class3/UCMM tag. A Class1 tag cannot used for the target.
■Buffer memory area assigned to a tag
For a tag registered as a Class3/UCMM tag in "EtherNet/IP Configuration", the buffer memory area to be assigned changes
according to the set connection number (1 to 256).
The following table shows the buffer memory areas corresponding to the connection numbers set for the tag name.
Connection
No.1
No.2

No.256
*1 The buffer memory address for connection number n can be calculated by 8278016+(n-1)  722.
*2 The module number (_1) changes depending on the system configuration.
■Read/Write request size
A Read/Write request size can be calculated by (Data Type)  (Data Size) of a tag.
Item
Data Type
Data Size
If the Read/Write request size exceeds the data size of the tag registered as a Class3/UCMM tag, without
executing Read/Write, an abnormal response is returned to the client.
■Read/Write execution
The following table shows the operations when a Read/Write request is received.
Type
Read
Write
If the Write request size is smaller than the data size of the tag registered as the Class3/UCMM tag, the data
contained in the area where Write was not performed upon receiving a response will not be altered.
12 FUNCTIONS
290
12.4 Message Communication Function (Server)
*1
Buffer memory area
Un\G8278016
Un\G8278738

Un\G8462126
Description
• INT: 1 word
• DINT: 2 words
Size of request data from the client
Description
When a Read request is received from the external device (client), sends data of the requested size, starting from the start
address corresponding to each connection number in 'Class3/UCMM data area (tag communications)' (Un\G8278016 to
Un\G8462847), to the client.
When a Write request is received from the external device (client), writes data of the requested size, starting from the start
address corresponding to each connection number in 'Class3/UCMM data area (tag communications)' (Un\G8278016 to
Un\G8462847).
*2
Module label
GN11_SE_1.EIP.stnArea_Cls3UCMMTagDataArea[1].unArea_Cls3UCMMTagData_D
GN11_SE_1.EIP.stnArea_Cls3UCMMTagDataArea[2].unArea_Cls3UCMMTagData_D

GN11_SE_1.EIP.stnArea_Cls3UCMMTagDataArea[256].unArea_Cls3UCMMTagData_D