Mitsubishi Electronics FX3G User Manual

FX

3S

/FX

3G

/FX

3GC

/FX

3U

/FX

3UC

 Series

Programming Manual - Basic & Applied Instruction Edition

37 Operation of Special Devices (M8000 -, D8000 -)

FNC277

-F

NC2
79

Da

ta

 

Trans
fer 3

FNC28

0-F

NC
289

H

igh-Speed 

Process

ing 2

FNC2

90-
FNC299

Ex

tensi

on Fi
le

 

Register C

ontrol

FN

C300-

FNC30

5

FX

3U

-C

F-

AD

P

SFC

•STL

Programming

Interrupt 

Function

Sp

ec

ia

l D

evi

ce

E

rror Code

Ve

rsi

on U

p 

Inform

ati

on

Ex

ecuti

on

 T

imes

When M8030 is set to ON, the battery LED does not turn ON even if the voltage in the battery for memory backup
becomes low.
When the indication of "battery voltage low error" is not required or when the battery is removed, set M8030 to ON.
When batteryless operation is required in FX

3U

/FX

3UC

 PLCs, do not use M8030 and refer to "1. Batteryless operation

by parameter setting in peripheral equipment" below.

Specify "batteryless operation" mode in the parameter settings.
1) When the batteryless operation option is specified

When "batteryless mode" is specified, the control to turn OFF the BATT (BAT) LED and initialization of the latch
area for the devices shown below are automatically executed by the PLC system.
- Auxiliary relay (M)

- Counter (C)

- State relay (S)

- Data register (D)

- Timer (T)

- Extension register (R)

2) Applicable programming tool

Some programming tool versions do not support "batteryless mode". In such versions, input a sequence program
to enable the batteryless operation as explained below.

1) An FLROM (optional memory cassette) for program memory is installed so that programs are not erased. (only in

FX

3U

/FX

3UC

 PLCs)

2) The latch (battery backed) devices such as auxiliary relays and data registers are not used for control.
3) The sampling trace function is not used.
4) The real time clock function is not used. (only in FX

3U

/FX

3UC

 PLCs)

When a parameter setting for "batteryless mode" is not available, create the sequence program shown below.
• Example program for clearing the memory backup area 

{when the latch (battery backed) ranges in the parameter settings are set to their initial values.}

*1.

The device number is the default number of the latch (battery backed) device range limits in the parameter
settings. 
If the latch (battery backed) device numbers in the parameter settings are changed to other values, change
the device numbers here in accordance with the changed latch ranges.

Special data registers D8120 (communication format), D8121 (station number setting) and D8129 (timeout check
time) are backed up by the battery in FX

3U

/FX

3UC

 PLCs.

When performing the batteryless operation in FX

3U

/FX

3UC

 PLCs, reset these special data registers using the

procedure described above, and then transfer proper set values to them using a program.
The communication conditions can be set in the parameter settings.
When the communication conditions are set in the parameter settings, the PLC transfers the parameter values to the
above special data registers before operation. Thus it is recommended to set the communication conditions via the
parameter settings.

M8000

RUN monitor

FNC 40

ZRST

M500

*1

M7679

M8002

Initial pulse

Auxiliary relay

S500

*1

S4095

State relay

T246

T255

Timer

C100

*1

C199

*1

C220

*1

C255

*1

32 bit counter

D200

*1

D7999

Data register

M8030 BATT(BAT) LED turns OFF.

16 bit counter

FNC 40

ZRST

FNC 40

ZRST

FNC 40

ZRST

FNC 40

ZRST

FNC 40

ZRST

R0

R32767

FNC 40

ZRST

or

M8000

RUN monitor

M8002

Initial pulse

M8030 BATT(BAT) LED

turns OFF.

M8032 The latch areas

are cleared.