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31 Applied Instructions (Data Transfer 3)
31.1 RBFM / Divided BFM Read
732
FXCPU Structured Programming Manual
[Basic & Applied Instruction]
Cautions
1) A watchdog timer error may occur when many numbers of points are transferred in one operation cycle.
In such a case, take either of the following countermeasures.
a) Change the watchdog timer time
By overwriting the contents of D8000 (watchdog timer time), the watchdog timer detection time is
changed (initial value: K200).
When the program shown below is input, the sequence program will be monitored with the new
watchdog timer time.
b) Change the number of transferred points "n2" in each operation cycle.
Change the number of transferred points "n2" in each operation cycle to a smaller value.
2) Do not stop the driving of the instruction while it is being executed. If driving is stopped, the buffer
memory (BFM) reading/writing processing is suspended, but the data acquired in the middle of reading/
writing processing is stored in the device specified by and later and buffer memories (BFM).
3) When indexing is executed, the contents of index registers at the beginning of execution are used.
Even if the contents of index registers are changed after the instruction is executed, such changes do not
affect the process of the instruction.
4) The contents of "n1" devices starting from the device specified by change while RBFM instruction is
executed. After execution of the instruction is completed, execute another instruction for "n1" devices
starting from the device specified by .
5) Do not update (change) the contents of "n1" devices starting from the device specified by while
WBFM instruction is executed. If the contents are updated, the intended data may not be written to the
buffer memories (BFM).
6) Do not update (change) the contents of "n1" buffer memories (BFM) starting from the buffer memory NO.
"m2" while RBFM instruction is executed. If the contents are updated, the intended data may not be read.
7) RBFM instruction is provided in the FX
3UC PLC Ver. 2.20 or later.
M8002
Initial pulse
Watchdog timer time: 300ms
Watchdog timer refresh
When WDT (FNC07) instruction is not
programmed, the value of D8000
becomes valid during END processing.
MOV
EN
s
ENO
d
WDT
EN ENO
K300 D8000
M
M8029
Instruction execution complete
SET
EN ENO
d
RST
EN ENO
d
RBFM
EN ENO
m1
m2
n1
n2
d
M
Unit number
Head BFM number
Number of all buffer memories
(BFM) to be read
Number of points transferred
in one operation cycle
Head device storing data to be
read from buffer memory (BFM)
M
LDP
EN
s
ENO
Command
input