Mitsubishi Electric MELSEC-FX3S Series - Buffer Memory Reading;Writing Method; Buffer Memory Direct Specification (FX 3 U;FX 3 UC PLC Only; FROM;TO Instruction (FX 3 G;FX 3 GC;FX 3 U;FX 3 UC PLC

E-17
5 Buffer Memory (BFM)
A
Common Items
B
FX
3U
-4AD
FX
3UC
-4AD
C
FX
3U
-4AD-ADP
D
FX
3G
-2AD-BD
E
FX
3U
-4DA
F
FX
3U
-4DA-ADP
G
FX
3G
-1DA-BD
H
FX
3U
-3A-ADP
I
FX
3U
-4AD-PT
-ADP
J
FX
3U
-4AD-PTW
-ADP
FX 3S /FX 3G /FX 3GC /FX 3U /FX 3UC PLC User's Manual - Analog Control Edition
FX3U-4DA (4-channel Analog Output)
5.2 Buffer Memory Reading/Writing Method
5.2 Buffer Memory Reading/Writing Method
To read or write the buffer memory of FX3U-4DA, use FROM/TO instructions or the buffer memory direct
specification function
*1
.
To use the buffer memory direct specification function
*1
, however, it is necessary to adopt the software
compatible with the PLC.
*1. This function is supported only in FX
3U/FX3UC PLCs.
→ For a detailed description of the software compatible with the PLC,
refer to Section 1.4.
5.2.1 Buffer memory direct specification (FX3U/FX3UC PLC only)
When directly specifying the buffer memory, specify the following device in the source or destination area of
the applied instruction as follows:
1. Example 1
If the following program is created, data in buffer memory (BFM#10) of unit 1 will be multiplied by the data
(K10), and then the multiplication result will be output to the data registers (D10, D11).
2. Example 2
If the following program is created, the value in the data register (D20) is added to K10 and written to buffer
memory (BFM#6) of unit 1.
5.2.2 FROM/TO instruction (FX3G/FX3GC/FX3U/FX3UC PLC)
1. FROM instruction (Reading out BFM data to PLC)
Use FROM instruction to read out the data from the buffer memory.
In a sequence program, use this instruction as follows:
If the above program is created, 1 point of data will be read out from the buffer memory BFM#10 of unit No.1
to the data register (D10).
2. TO instruction (Writing PLC data into BFM)
Use the TO instruction to write data to a buffer memory.
In a sequence program, use this instruction as follows:
If the above program is created, 1 point of data (H3300) will be written to buffer memory (BFM#0) of unit No.1.
Buffer memory number (0 to 32766)
U\G
Enter a numeric value in 
Unit number (0 to 7)
FNC 22
MUL
U1\G10 K10 D10
Multiplier
Multiplication result
Unit number
Buffer memory number
READ command
WRITE command
FNC 20
ADD
D20 K10 U1\G6
Addend
Augend
Unit number
Buffer memory number
Addition
result
READ command
FNC 78
FROM
K1 K10 D10 K1
Transfer-to register
Number of transfer
data points
Unit number
Buffer memory number
WRITE command
FNC 79
TO
K1 K0 H3300 K1
Transfer source
Number of transfer
data points
Unit number
Buffer memory number