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14 Applied Instructions (External FX I/O Device)
14.9 FROM / Read From A Special Function Block
384
FXCPU Structured Programming Manual
[Basic & Applied Instruction]
14.9.1 Common terms of FROM/TO instruction (detail)
Specification content of operand
1. Unit number n1 of special extension unit/block
Unit number is used for specifying which equipment is the object of working for FROM/TO instruction.
Setting range: K0 to K7
The unit number is assigned automatically to the special extension unit/block connected to the PLC.
The unit number is given from the one closest to the basic unit in the sequence of No. 0, No. 1, No.2, etc.
In the case of the FX
3UC-32MT-LT(-2) PLC, since the CC-Link/LT master is built in, the unit number is given
from the one closest to the basic unit in the sequence of No. 1, No.2, No. 3, etc.
2. Buffer memory (BFM) number "n2"
In the special extension unit/block, 16-bit RAM is built in, and it is used as the buffer memory.
The buffer memory numbers are #0 to #32766, and the content is determined depending on the control
purpose of each equipment.
Setting range: K0 to K32766
• When BFM is handled in 32-bit instruction, the specified BFM is lower 16 bits, and the BFM of the next
number is higher 16 bits.
3. Transfer points "n3"
Setting range: K1 to K32767
Number of transfer words is specified by n3.
"n =2" in a 16-bit instruction indicates the same meaning with "n = 1" in a 32-bit instruction.
Interrupt accept during execution of FROM/TO (M8028)
Applicable to the FXU (at Ver. 2.30 or later), FX2C, FX2N, FX2NC, FX3G, FX3GC, FX3U and FX3UC PLCs only.
1. When M8028=OFF
Interrupt is prohibited automatically during execution of FROM/TO instruction, and input interrupt or timer
interrupt is not executed.
An interrupt occurring in this period is executed immediately after completion of execution of FROM/TO
instruction.
FROM/TO instruction can be used also during the interrupt program.
2. When M8028=ON
When an interrupt occurs during execution of FROM/TO instruction, the execution is suspended, and the
interrupt program is executed.
However, FROM/TO instruction cannot be used during interrupt program.
FX
3UC
-32MT
-LT(-2)
Basic unit
Unit
No. 0
built-in
CC-Link/LT
Input/output
extension
block
Special
extension
block
Special
extension
block
Special
extension
block
Input/output
extension
block
Unit
No. 1
Unit
No. 2
Unit
No. 3
BFM #10 BFM #9
Lower 16 bitsHigher 16 bits
Specified BFM numbe
r
←
D100
D101
D102
D103
D104
BFM #5
#6
#7
#8
#9
Specified device Specified BFM
D100
D101
D102
D103
BFM #5
#6
#7
#8
Specified device Specified BFM
16-bit operation when n=5
32-bit operation when n=2