Buffer Memory Reading/Writing Method; Buffer Memory Direct Specification (Fx 3U /Fx 3Uc Plc Only; From/To Instruction (Fx 3G /Fx 3Gc /Fx 3U /Fx 3Uc Plc - Mitsubishi Electric MELSEC-FX3S Series Manual

FX /FX /FX /FX /FX
3S 3G 3GC 3U 3UC
FX -4AD/FX -4AD (4-channel Analog Input)
3U 3UC
5.2

Buffer Memory Reading/Writing Method

To read or write to the 4AD buffer memory, use the FROM/TO instructions or buffer memory direct
*1
specifications .
However, to use buffer memory direct specification
required.
*1. This function is supported only in FX
5.2.1 Buffer memory direct specification (FX
When directly specifying the buffer memory, specify the following device in the source or destination area of
the applied instruction as follows:
Unit number (0 to 7)
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 data registers (D10, D11).
READ command
Unit number
Buffer memory number
2. Example 2
If the following program is created, the value in data register (D20) is added to K10 and written to buffer
memory (BFM#6) of unit 1.
WRITE command
Augend
5.2.2 FROM/TO instruction (FX
1. FROM instruction (Reading out BFM data to PLC)
Use the FROM instruction to read the data from the buffer memory.
In a sequence program, use this instruction as follows:
READ command
Unit number
Buffer memory number
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 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:
WRITE command
Unit number
Buffer memory number
If the above program is created, 1 point of data (H3300) will be written to buffer memory BFM#0 of unit No.1.
PLC User's Manual - Analog Control Edition
3U
→ For a detailed description of software compatible with the FX
U\G
FNC 22
U1\G10
MUL
FNC 20
D20
ADD
/FX /FX
3G 3GC
FNC 78
K1 K10
FROM
FNC 79
K1 K0
TO
*1
, software compatible with FX
/FX PLCs.
3UC
/FX PLC only)
3U 3UC
Enter a numeric value in 
Buffer memory number (0 to 32766)
K10 D10
Multiplication result
Multiplier
K10 U1\G6
Addition
result
Addend
/FX PLC)
3U 3UC
D10 K1
Number of transfer
data points
Destination register
H3300 K1
Number of transfer
data points
Transfer source
5 Buffer Memory (BFM)
5.2 Buffer Memory Reading/Writing Method
/FX Series PLCs is
3U 3UC
/FX Series PLC,
3U 3UC
refer to Section 1.4.
( )
Unit number
Buffer memory number
A
B
C
D
E
F
G
H
I
J
B-21