Table of Contents
FX
/FX
/FX
Series Programmable Controllers
3G
3U
3UC
Programming Manual - Basic & Applied Instruction Edition
15.9
FNC 78 – FROM / Read From A Special Function Block
Outline
This instruction reads the contents of buffer memories (BMF) in a special extension unit/block attached to a
PLC.
When a large capacity of buffer memory (BFM) data is read by this instruction, a watchdog timer error may
occur. When bad effect is not given to the control even if data to be read is divided, use RBFM (FNC278)
instruction.
1. Instruction format
FNC 78
D
FROM
P
2. Set data
Operand Type
m1
m2
D
n
3. Applicable devices
Bit Devices
Oper-
and
System User
Type
X Y M T C S D .b KnX KnY KnM KnS T C D R U \G
m1
m2
D
n
Explanation of function and operation
1. 16-bit operation (FROM and FROMP)
Special extension unit/block (BFM) → PLC (word device)
"n"-point 16-bit data starting from the buffer memory (BFM) # m2 inside a special extension unit/block No. m1
are transferred (read) to "n"-point 16-bit data starting from
Command
input
FNC 78
FROM
Mnemonic
16-bit Instruction
FROM
9 steps
FROMP
Unit number of a special extension unit/block
(K0 to K7 from the right side of the main unit)
Transfer source buffer memory (BFM) number
Transfer destination device number
Number of transfer points
Digit Specification
→ For the common items between FROM instruction and TO instruction,
m1
m2
D
15 External FX I/O Device – FNC 70 to FNC 79
15.9 FNC 78 – FROM / Read From A Special Function Block
→ For RBFM (FNC278) instruction, refer to Section 31.1.
Operation Condition
32-bit Instruction
Continuous
17 steps
Operation
Pulse (Single)
Operation
Description
Word Devices
Special
System User
Unit
V Z Modify K H
inside a PLC.
D
n
Number of transfer points
n = 1 to 32767
Transfer destination (PLC)
Transfer source BFM #
(Special extension unit/block)
m2 = 0 to 32766
Unit No.
m1 = 0 to 7
Mnemonic
Operation Condition
Continuous
DFROM
Operation
Pulse (Single)
DFROMP
Operation
Data Type
16- or 32-bit binary
16- or 32-bit binary
16- or 32-bit binary
16- or 32-bit binary
Others
Con-
Real
Charac-
Index
stant
Number
ter String
E
" "
refer to Subsection 15.9.1.
11
12
13
14
15
16
Pointer
P
17
18
19
20
467
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