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3 SPECIFICATION
MELSEC-QnA
3.5 Buffer Memory
The buffer memory is used to swap data between the master/local module and the
programmable controller CPU.
In the programmable controller CPU, the FROM/TO instructions are used to read/write
data.
The contents of the buffer memory return to the default values when the power is
turned off and the programmable controller CPU is reset.
3.5.1 Buffer memory list
The buffer memory list is shown in Table 3.4.
When using a master/local module as a standby master station, refer to the respective
columns under "Availability" in the table as explained below.
x When a standby master station is operating as a master station: "Master station"
column
x When a standby master station is operating as a standby master station: "Local
station" column
Table 3.4 Buffer memory list (1/2)
Address Availability
Hex. Dec.
Item Details
Read/write
possibility
Master station
Local
station
Reference
0H to
5F
H
0 to 95
Parameter information
area
Stores the information (parameters)
to execute the data link.
Read/write
enabled
(Not available when a
standby master station is
controlling the system)
Section
3.5.2 (1)
60H to
7F
H
96 to
127
(Prohibited to use)
– – – – –
80H to
CD
H
128 to
205
Parameter information
area
Stores the information (parameters)
to execute the data link.
Read/write
enabled
(Not available when a
standby master station is
controlling the system)
Section
15.2.1
CEH to
DF
H
206 to
223
(Prohibited to use)
– – – – –
When master station: Stores the
input status from the remote/local
station.
–
E0H to
15F
H
224 to
351
Remote input (RX)
When local station: stores the input
status from the master station.
Read only
–
When master station: Stores the
output status of the output to the
remote/local station.
Write only
–
160H
to
1DF
H
352 to
479
Remote output (RY)
When local station: Stores the output
status of the output to the master
station.
Read/write
enabled
–
Section
3.5.2 (2)
When master station: Stores the
transmission data to the remote/all
local stations.
Write only
–
1E0H
to
2DF
H
480 to
735
Remote register (RWw)
(Master station:
for sending
Local station:
for sending/receiving)
When local station: Stores the
transmission data to the
master/other local stations. Also,
stores the received data from the
remote/other local stations.
Read/write
enabled
–
Section
3.5.2 (3)
: Usable : Prohibited to use
* Do not write to areas that are prohibited to use. An error may occur.