FX Series Programmable Controllers Devices in Detail 4
4-35
4.12.2 Battery Backed/ Latched Registers
Once data is written to a batter
backed re
ister, it remains unchan
ed until it is overwritten.
When the PLC’s status is chan
ed from RUN to STOP, the data in these re
isters is retained.
The ran
e of devices that is batter
backed can be chan
ed b
ad
ustin
the parameters of the
PLC. For details of how to do this please refer to the appropriate pro
rammin
tools manual.
Using the FX
2
-40AW/AP:
• When usin
an FX with either the FX2-40AWor the FX2-40AP a proportion of the latched
data re
isters are automaticall
assi
ned for communications use b
the FX2-40AW/AP
module.
Communication between Master and Slave 100 points M800 to M899
10 points D490 to D499
Communication between Slave and Master 100 points M900 to M999
10 points D500 to D509
4.12.3 Special Diagnostic Registers
Special re
isters are used to control or monitor various modes or devices inside the PLC. Data
written in these re
isters are set to the default values when the power suppl
to the PLC is
turned ON.
- Note: When the power is turned ON, all re
isters are first cleared to 0 (zero) and then the
default values are automaticall
written to the appropriate re
isters b
the s
stem
software. For example, the watchdo
timer data is written to D8000 b
the s
stem
software. To chan
e the settin
, the user must write the required value over what is
currentl
stored in D8000.
Data stored in the special dia
nostic re
isters will remain unchan
ed when the PLC is
switched from STOP mode into RUN.
Use of diagnostic registers:
• On no account should unidentified devices be used. If a device is used, it should onl
be
for the purpose identified in this manual. Please see chapter 6 for tables containin
data
and descriptions of the available devices for each PLC.
