1. OUTLINE
1
−
6
MELSEC-A
(2)
Outline of Message Communication
Message communication is a function to read and write slave station attribute data.
An outline of message communication is shown below. See 4.2 Message Communication
Functions for details.
(a) Reading attributes
Slave station
DN91
PLC CPU
D, R
TO
Attribute
Attribute
Message
communication
command area
Message
communication
result area
Message
communication
data area
(Up to 240 byte)
D, R
FROM
Device
Class
Instance
Instance
Class
Instance
Attribute
Instance
Attribute
Attribute
Attribute
Attribute
FROM
Device