Mitsubishi QJ71MT91 User Manual page 66

5 FUNCTIONS
QJ71MT91 (Master function)
Buffer memory
Automatic
Programmable
communication
controller CPU
function buffer
side read direction
input area
(1000
Automatic
Programmable
communication
controller CPU
function buffer
side write direction
output area
(3000
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(4) Automatic communication function buffer areas
(a) Automatic communication function buffer areas
The automatic communication function uses the following buffer memory
areas.
Name
Automatic communication function
buffer input area
Automatic communication function
buffer output area
(b) Transfer direction of automatic communication function buffer
input/output area
The following shows the transfer directions of data stored into the buffer
memory by the automatic communication function.
1) Transfer direction in automatic communication function
buffer input area
When receiving a response message from the slave, the QJ71MT91
writes data to the automatic communication function buffer input area
in descending order of the addresses in 1 word (16 bits) unit.
2) Transfer direction in automatic communication function
buffer output area
When sending a request message to the slave, the QJ71MT91 creates
it by reading data from the automatic communication function buffer
output area in descending order of the addresses in 1 word (16 bits)
unit.
QJ71MT91
side receive
data write
direction
to 1FFF )
H H
QJ71MT91
side send
data read
direction
to 3FFF )
H H
Application
Stores data read from the
slave
Stores data to be written
to the slave
Ethernet
MELSEC-Q
Buffer Memory Address
1000 to 1FFF
H H
3000 to 3FFF
H H
R
MODBUS /TCP slave device
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