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4. FUNCTIONS
4.2 Message Communication Functions
4.2.1
Get attribute
The message communication functions read and write data to the slave station special area.
PC CPU
TO
SET
Y(n+1)2
FROM
Xn2
FROM
Xn2
Message communication
complete
1)
Set "Get Attribute" in the buffer memory message communication command area using
the sequence program TO instruction.
2)
Turn ON message communication request (Y(n+1)2) with a sequence program to send
the data set in the buffer memory message communication command area to the slave
stations and start message communication.
3)
DN91 receives data from the slave stations and processes it as follows:
•
The slave station special data set in the message communication command area is
stored in the message communication data area of the buffer memory.
•
The result of processing the message communication is stored in the message
communication results area of buffer memory.
4)
When the process result is stored in the message communication results area of buffer
memory, message communication ends and the message communication complete (Xn2)
signal automatically turns ON.
5)
When the slave station data ends normally in the buffer memory message communication
area, it is read to the PC CPU using the sequence program FROM instruction.
DN91
0110
H
Message
1)
communication
command area
011F
H
2)
Message communi-
cation request
0120
H
Message
communication
result area
012F
H
0130
H
Message
communication
data area
01A7
H
4)
Message communi-
cation complete
5)
−
4
3
MELSEC-A
Slave station (MAC ID)
Class
2)
Instance
Attribute
Attribute
Iinstance
Attribute
3)
Class
Instance
Attribute
Instance
Attribute
Attribute
Attribute
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Troubleshooting
