Siemens Simatic Industrial PC IPC427C - Manual (Page 52)

Functions
9.4 SRAM buffer memory
SIMATIC IPC427C
52
Operating Instructions, 04/2009, A5E02414743-01
9.4 SRAM buffer memory
For applications to be able to store data following a power failure, the motherboard features
a battery-buffered CMOS-RAM. If the supply voltage fails longer than 5 ms, this is indicated
by the DC FAIL signal.
Enough time is provided for copying data to the buffered RAM that 256 KB can be saved
with a full configuration.
A maximum 2048 Kb memory window is displayed via a PCI address register. The base
address is initialized by the BIOS.
A corresponding function is implemented there for using the CMOS-RAM under WinAC RTX.
NOTICE
If replacement of the battery takes longer than 30 seconds, the data saved in the CMOS
RAM and in the buffered SRAM is lost.