FPΣ User's Manual 
 
6.8 Backup Battery 
97 
4.  Choose "Enable" in the list box of item no. 4 "Battery error indication" 
 
6.8.3 Specifying Hold Areas 
If no battery is installed, only the fixed hold areas (default address ranges of system registers 
6 to 14) will be saved when the PLC is turned off. With the optional backup battery it is 
possible to save additional hold areas.  
 
1.
2.
3.
Procedure
 
1.  Double-click "PLC" in the navigator 
2.  Double-click "System Registers" 
3.  Double-click "Hold On/Off" 
Enter the desired values for hold areas in system registers no. 6 to 14. (For 
internal relays and data registers, a dialog box opens in which you can adjust the 
values.) 
CAUTION
 
Do not change the default values if no battery is installed. If the battery is empty 
or no battery is present and additional hold areas have been defined, the 
hold/non-hold operation becomes unstable. 
 
6.8.4 Lifetime of the Backup Battery 
The backup battery will eventually die. Therefore it is important to replace it periodically. Refer 
to the table below as a guide for when to replace the battery. 
 
Item  Description 
Battery life 
220 days or more if no power at all is supplied (typical lifetime in actual use: approx. 840 
days at 25°C/70°F) 
Suggested replacement interval: 1 year