Function Of Transfer Between File Registers And Data Registers - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
9.6.1

Function of transfer between file registers and data registers

BMOV (FNC 15) instruction has a special function for file registers (D1000 and later).
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 (FNC 15) instruction and other instructions
The table below shows the difference between BMOV (FNC 15) instruction and other instructions with
regard to file registers (D1000 and later).
Instruction
BMOV
instruction
Other applied
instructions
When restoring the power, data registers set as file registers are automatically copied from the file
register area [A] to the data register area [B].
D1000
500 points ×
14 blocks
maximum
(7000 points
maximum)
268
Contents of transfer
Can read from and write to the file register
area [A] inside the program memory.
Can read from and write to the data register
area [B] inside the program memory in the
same way as general data registers.
Inside built-in memory
or memory cassette
Program
When power
memory
is turned ON
When PLC
Program/
mode is
comment
changed from
STOP to
File register
RUN
[A]
9 Move and Compare – FNC 10 to FNC 19
→ For details on file registers, refer to Section 4.8.
Because the data register area [B] is provided
inside the system RAM in PLCs, its contents can be
arbitrarily changed without regard to the memory
cassette format
Inside system
RAM
D 0
Data
memory
Data register
D1000
Write
Data register
[B]
Read
Data register
D7999
The remaining area can be used as general purpose
data registers.
9.6 FNC 15 – BMOV / Block Move
Remarks
−
Devices D1000 and later specified as
operands in applied instructions other
than BMOV (FNC 15) , 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.