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MELSEC-Q
7 PROGRAMMING WHEN EXECUTING THE MASTER FUNCTION
7.5 Performing Message Communication
This section explains an example of a sequence program that performs message
communication.
7.5.1 Example of message communication read
The following shows an example of a sequence program that reads attributes from
node number 3.
In sections enclosed with a dashed line, the area that is actually read and written as
well as the class ID, instance ID and attribute ID are different depending on the slave
node. Therefore, refer to the applicable manual of the slave node.
Attribute read
command
Attribute read
command
Attribute read
command
Reads the master communication status.
Executes attribute read if the master
communication status is either C0
H
or 40
H
.
Sets the attribute read command.
Slave station of station No. 3,
class ID = 1
Instance ID = 1
Attribute ID = 7
Writes request data into the buffer memory.
Sets the message communication request.
Obtains the reception data read length.
Calculates the reception data read length.
Reads the reception data.
Resets the message communication request.
Error handling program