Mitsubishi Electric MELSEC FX3U Programming Manual page 743

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Explanation of function and operation
1. 16-bit operation (RBFM)
"n1" buffer memory (BFM) units at location # "m2" in special function unit/block No. "m1" are read to
the PLC. While transfering, "n1" is divided by "n2" so n1/n2 buffer memories (rounded up when there is a
remainder) are transferred per scan time
Command
input
M8029
M8328
M8329
• 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 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 other target instruction is complete, the paused instruction resumes.
Related devices
→ For the flag use methods for instruction execution complete and instruction execution
Device
M8029 Instruction execution complete
M8328 Instruction non-execution
M8329 Instruction execution abnormally complete
Related instructions
Instruction
FROM(FNC 78)
TO(FNC 79)
WBFM(FNC279)
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)
→ For the unit No., buffer memory (BFM) #, cautions, and program example,
FNC278
m1 m2
RBFM
Instruction execution
M
complete
Instruction
M
non-execution
Instruction execution
M
abnormally complete
Name
Read from a special function block
Write to a special function block
Divided BFM write
31 Data Transfer 3 – FNC275 to FNC279
31.1 FNC278 – RBFM / Divided BFM Read
Unit No. "m1"
D n1 n2
BFM#(m2)
BFM#(m2+n1-1)
abnormally complete, refer to Subsection 6.5.2.
Turns ON when an instruction is finished normally.
Turns ON when RBFM (FNC278) or WBFM (FNC279)
instruction in another step is executed for the same unit
number.
Turns ON when an instruction is finished abnormally.
Description
refer to Subsection 31.1.1.
PLC
*1
Read
D
+n1-1
D
*1 "n2" buffer memories are read in
each operation cycle. Reading is
executed in "n1/n2" times. ("n1/n2"
is rounded up if it is not an integer.)
Description
31
in
D
32
33
34
35
36
37
38
A
B
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