Mitsubishi Electric FX3G SERIES Programming Manual page 260

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
5) Handling of the memory cassette
When changing the contents of file registers secured inside the memory cassette, confirm the following
conditions:
- Set the protect switch of the memory cassette to OFF.
- In FX /FX
3U
a) It takes 66 to 132 ms to write data in one continuous block (500 points) to the memory cassette (flash
memory).
Execution of the program is paused during this period. Because the watchdog timer is not refreshed during
this period, it is necessary to take proper countermeasures such as inserting the WDT instruction into the
sequence program.
b) Do not turn OFF the power while the contents of file registers are changed.
If the power is turned OFF during the change, the data stored in file registers may be filled with unexpected
values, or a parameter error may occur.
- In FX PLCs
3G
It takes 80 ms to write data in one continuous block (500 points) to the memory cassette (EEPROM).
Note that execution of the program is paused during this period, but the watchdog timer is automatically
refreshed.
6) Allowable number of times of writing to the memory
Data can be written to the memory cassette up to 10,000 times, and to the memory (EEPROM) built in FX
up to 20,000 times.
When a continuous operation type instruction is used for data writing in a program, data is written to the memory
in every operation cycle of the PLC. To prevent this, make sure to use a pulse operation type instruction
(BMOVP).
7) File register operation
File registers are secured inside the built-in memory or memory cassette.
Different from general data registers, file registers can be read and written only by peripheral equipment or BMOV
(FNC 15) instruction.
8) If a file register is not specified as the destination in BMOV (FNC 15) instruction, the file register is not accessed.
a) Outline of memory operation
500 points ×
14 blocks
maximum
(7000 points
maximum)
b) Program example
When X000 is set to ON, the data register area [B] is read.
X000
A file register can be specified as
register update mode is selected.
However, even if a file register having different number is specified for
cannot be transferred from the file register area to another file register area. In such a case, read the contents
of a file register specified as
once, and then write the data.
258
PLCs
3UC
Inside built-in memory
or memory cassette
Program
memory
Program/
comment
D1000
File register
[A]
S
FNC 15
D1100 D200
BMOVP
S
→ For the same-number register update mode of file registers, refer to Subsection 4.8.2.
Inside system
RAM
D 0
D200
Image
memory
Data register
D599
D1100
Data register
[B]
D1499
Data register
D7999
D
n
K400
. But if the same number with
D
in the same-number register update mode to the data register area [B]
9 Move and Compare – FNC 10 to FNC 19
9.6 FNC 15 – BMOV / Block Move
is specified, the same-number
S
and respectively, data
S D
PLCs
3G