Cautions On Using File Registers - Mitsubishi Electric FX3G SERIES Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
2) When file registers of different device numbers are specified for the source and destination
Inside built-in
memory or
memory cassette
Program
memory
Program/
comment
D1000
500 points ×
File register
14 blocks
[A]
maximum
(7000 points
maximum)
4.9.5

Cautions on using file registers

1. Cautions on using a memory cassette
When changing the contents of file registers stored in the memory cassette, confirm the following conditions:
• Set to OFF the protect switch in the memory cassette.
• In FX /FX
3U 3UC
- 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.
- 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.
2. Allowable number of writes 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).
3. Cautions on handling file registers in the same-number register update mode in BMOV (FNC 15)
instruction
• When updating the contents of the same number file register, make sure that the file register number at
D are equal to each other.
• Make sure that the number of transfer points specified by "n" does not exceed the file register area.
• If the number of transfer points specified by "n" exceeds the file register area, an operation error (M8067) occurs
and the instruction is not executed.
• In the case of indexing
When S
register area and the number of transfer points is within the file register area also.
132
Inside system
RAM
D 0
Data
memory
Data register
Write
Data register
D1400
[B]
D1499
Data register
D7999
PLCs
and D are indexed, the instruction is executed if the actual device number is within the file
Write
OFF
X001
• When X001 is set to ON, the contents of the data
register area [B] are transferred to the data register
D1100
area [B] and file register area [A] as shown in the
D1199
figure on the left.
D1400
If data cannot be written to the file register area [A]
D1499
because the protect switch of the memory cassette is
ON, data is written to only the data register area [B].
4 Devices in Detail
4.9 Data Register and File Register [D]
M8024
S D
FNC 15
D1100 D1400
BMOVP
n
K100
PLCs
3G
S and