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Programming Manual - Basic & Applied Instruction Edition

31 Data Transfer 3 – FNC277 to FNC279

31.1 FNC278 – RBFM / Divided BFM Read

Cautions

• A watchdog timer error may occur when many numbers of points are transferred in one operation cycle. In such a

case, take one of the following countermeasures:
- 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.

- 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.

• 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

and later and buffer memories (BFM).

• 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, such changes do not affect the process of
the instruction.

• The contents of "n1" devices starting from

change while the RBFM (FNC278) instruction is executed. After

execution of the instruction is completed, execute another instruction for "n1" devices starting from

• Do not update (change) the contents of "n1" devices starting from

while the WBFM (FNC279) instruction is

executed. If the contents are updated, the intended data may not be written to the buffer memories (BFM).

• Do not update (change) the contents of "n1" buffer memories (BFM) starting from the buffer memory No. "m2" while

the RBFM (FNC278) instruction is executed. If the contents are updated, the intended data may not be read.

M8002

Initial pulse

FNC 12

MOV

K300

D8000

FNC 07

WDT

Watchdog timer time: 300 ms

Watchdog timer refresh

When WDT (FNC 07) instruction is not programmed, the value

of D8000 becomes valid during END processing.

Command

input

M{{

SET

M{{

M8029

RST

M{{

Instruction execution complete

FNC278

RBFM