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FX Series Programmable Controllers Devices in Detail 4
4-36
4.12.4 File Registers
File re
g
isters are available in two forms:
-Pro
g
ram memor
y
re
g
isters - these occup
y
pro
g
ram steps in blocks of 500 and are avail-
able on FX
0N
, FX, FX
2C
and FX
2N(C)
products
- RAM re
g
isters - these occup
y
a special data area and are available on all FX
2C
units and
FX units with CPU version 3.07 or
g
reater.
Program memory registers
File re
g
isters can be secured in the pro
g
ram memor
y
(RAM, EEPROM or EPROM) in units of
500 points. These re
g
isters can be accessed with a peripheral device. While the PLC is
operatin
g
, data in the file re
g
isters can be read to the
g
eneral-use/ batter
y
backed/ latched
re
g
isters b
y
usin
g
the BMOV instruction.
File re
g
isters are actuall
y
setup in the parameter area of the PLC. For ever
y
block of 500 file
re
g
isters allocated and equivalent block of 500 pro
g
ram steps are lost.
Note: The device ran
g
e for file re
g
isters in the FX
2N(C)
overlaps with the latched data re
g
isters.
The allocation of these devices as file re
g
isters ensures that the data is kept with the pro
g
ram.
Writing to file registers:
•FX
0N
and FX file re
g
ister data can onl
y
be chan
g
ed b
y
a peripheral device such as a
hand held pro
g
rammer or a personal computer runnin
g
the appropriate software.
For details of how to carr
y
out the chan
g
es please reference the relevant operation
manual for
g
uidance.
•FX
(2C)
and FX
2N(C)
file re
g
ister data can also be chan
g
ed b
y
the pro
g
ram usin
g
the
BMOV instruction.
•Onl
y
file re
g
isters in RAM or internal memor
y
can be chan
g
ed durin
g
RUN, but both
RAM, internal and EEPROM memor
y
cassette memories can be chan
g
ed when the PLC
is in STOP mode.
Special caution when using FX
0N
:
• No file re
g
isters can be modified durin
g
RUN.
Special caution when using FX:
• While the FX PLC is in RUN mode, alteration of the file re
g
isters D1000 to D1119 (120
points) is not allowed. Attempts to chan
g
e these devices durin
g
RUN ma
y
result in a pro-
g
ram error when the PLC is next switched into RUN.
RAM registers
RAM file re
g
isters are 2000 points which can be activated b
y
drivin
g
a special auxiliar
y
rela
y
M8074 ON. These re
g
isters can then be accessed
j
ust like normal pro
g
ram file re
g
isters. RAM
re
g
isters occup
y
no pro
g
ram steps but do occup
y
the samplin
g
trace data re
g
ister area when
M8074 is active.
Available devices:
• Please refer to the table on pa
g
e 4-33 or chapters 6 and 8, where further details of the
availabilit
y
of devices can be found.