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FX3S/FX3G/FX3GC/FX3U/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
31 Data Transfer 3 – FNC277 to FNC279
31.2 FNC279 – WBFM / Divided BFM Write
31.2 FNC279 – WBFM / Divided BFM Write
Outline
This instruction writes data to continuous buffer memories (BFM) in a special function unit/block over several operation
cycles by the time division method. This instruction is convenient for writing send data, etc. to buffer memories in a
special function unit/block for communication by the time division method.
TO (FNC 79) instruction is also available for writing data to the buffer memory (BFM).
→ For TO (FNC 79) instruction, refer to Section 15.10.
1. Instruction format
2. Set data
3. Applicable devices
S: Except special data register (D)
Explanation of function and operation
1. 16-bit operation (WBFM)
"n1" word units from in the PLC are written to buffer memory (BFM) location # "m2" in special function unit/
block No. "m1". While transferring, "n1" is divided by "n2" so n1/n2 words (rounded up when there is a remainder) are
transferred per scan time.
→ For the unit No., buffer memory (BFM) No., cautions, and program example,
refer to Subsection 31.1.1.
• When the instruction is finished normally, the instruction execution complete flag M8029 turns ON. When the
instruction is finished abnormally, the instruction execution abnormally complete flag M8329 turns ON.
• When the RBFM (FNC278) or WBFM (FNC279) instruction is executed in another step for the same unit number,
the instruction non-execution flag M8328 is set to ON, and execution of such an instruction is paused.
When execution of the first target instruction is complete, the paused instruction resumes.
Operand Type Description Data Type
m1 Unit number [0 to 7]
16-bit binary
m2 Head buffer memory (BFM) number [0 to 32766]
Head device number storing data to be written to buffer memory (BFM)
n1 Number of all buffer memories (BFM) to be written [1 to 32767]
n2 Number of points transferred in one operation cycle [1 to 32767]
Oper-
and
Type
Bit Devices Word Devices Others
System User Digit Specification System User
Special
Unit
Index
Con-
stant
Real
Number
Charac-
ter String
Pointer
XYMTCSD
.b KnX KnY KnM KnS T C D R
U\G
V Z Modify K H E "
"P
m1
m2
S
n1
n2
FNC 279
WBFM
16-bit Instruction
11 steps
WBFM
Mnemonic Operation Condition
Continuous
Operation
−
Mnemonic Operation Condition
32-bit Instruction
S
S
S
Command
input
M{{
M8029
FNC279
WBFM
m1 m2 S n1 n2
M8328
M
Instruction execution
complete
Instruction
non-execution
Unit No. "m1"PLC
*1 "n2" points are written in each
operation cycle. Writing is executed
in "n1/n2" transfers. ("n1/n2" is
rounded up if it is not an integer.)
Write
*1
BFM#(m2)
BFM#(m2+n1-1)
+n1-1
S
S
M8329
MUU
Instruction execution
abnormally complete