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8 Applied Instructions (Move and Compare)
8.6 BMOV / Block Move
152
FXCPU Structured Programming Manual
[Basic & Applied Instruction]
Function of transfer between file registers and data registers
BMOV instruction has a special function to file registers (D1000 and later).
The maximum number of file register differs from one PLC to another.
This explanation here uses the FX
3U and FX3UC PLCs as examples.
For the details of the file registers, refer to the following manual.
→ FX Structured Programming Manual [Device & Common]
1. What are file registers
By parameter setting, D1000 to D7999 can be handled as file registers, and written to and read from the
program memory area.
1) Outline of setting
File registers (D1000 to D7999) do not exist in the initial status. They are valid only when some number of
file registers are secured by parameter setting in a programming tool.
2) Number of file registers
In parameter setting, set 500 file registers as 1 block.
1 to 14 blocks (each of which has 500 file registers) can be set.
1 block occupies 500 steps in the program memory area.
3) Difference between BMOV instruction and other instructions
The table below shows the difference between BMOV instruction and other instructions with regard to file
registers (D1000 and later).
When power is turned ON, data registers set as file registers are automatically copied from the file
register area [A] to the data register area [B].
2. Cautions on use
1) When updating the contents of a file register with a same number (same-number update mode), make
sure that the file register number is equivalent between and .
2) When using file registers in the same-number update mode, make sure that the number of transfer points
specified by "n" does not exceed the file register area.
3) If the file register area is exceeded while file registers are used in the same-number update mode, an
operation error (M8067) is caused and the instruction is not executed.
4) In the case of indexing (in the same-number update mode)
When and are modified with index, the instruction is executed if the actual device number is
within the file register area and the number of transfer points does not exceed the file register area.
Instruction Contents of transfer Remarks
BMOV
Can read from and write to the file register area [A]
inside the program memory.
-
Other applied
instructions than
BMOV
Can read from and write to the data register area
[B] inside the image memory in the same way as
general data registers.
Because the data register area [B] is provided inside the
system RAM in PLCs, its contents can be arbitrarily
changed without regard to the optional memory format.
Data register
[B]
Inside system RAM
Inside built-in memory
or
memory cassette
Program
memory
Program/
comment
file
register
[A]
D1000
When power is
turned ON
When PLC
mode is
changed from
STOP to RUN
Data
memory
Data register
Data register
D7999
D1000
Read
Write
Remaining area can be used as data register for general purpose.
Devices D1000 and later specified as
operands in applied instructions other
than BMOV, indirectly specified values
for timers or counters or devices in
RST instruction are read from and
written to the area [B] in the same
way as general data registers.
0D
500 points 14 blocks
maximum
(7000 points maximum)