Mitsubishi Digital Electronics FX2N Manual

A SERVICE OF

next previous

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.