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3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
31 Data Transfer 3 – FNC275 to FNC279
31.2 FNC279 – WBFM / Divided BFM Write
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 transfering, "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.
Related devices
→
For the flag use methods for instruction execution complete and instruction execution
abnormally complete, refer to Subsection 6.5.2.
Related instructions
Errors
An operation error is caused in the following case; The error flag M8067 turns ON, and the error code is
stored in D8067.
• When the unit number "m1" does not exist (error code: K6708)
Device
Name
Description
M8029
Instruction execution complete
Turns ON when an instruction is finished normally.
M8328
Instruction non-execution
Turns ON when RBFM (FNC278) or WBFM (FNC279)
instruction in another step is executed for a same unit number.
M8329
Instruction execution abnormally complete
Turns ON when an instruction is finished abnormally.
Instruction
Description
FROM(FNC 78)
Read from a special function block
TO(FNC 79)
Write to a special function block
RBFM(FNC278)
Divided BFM read
S
Command
input
M
{{
M8029
FNC278
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
M
UU
Instruction execution
abnormally complete