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The AADvance Safety Controller Chapter 2 Processor Back-up Battery
The 9110 processor module has a back-up battery that powers its internal
Real Time Clock (RTC) and a part of the volatile memory (RAM). The
battery only supplies power when the processor module is no longer
powered from the system power supplies. The specific functions that the
battery maintains on complete loss of power are:

Real Time Clock - The battery supplies power to the RTC chip
itself.

Retained Variables - Data for retained variables is stored at the end
of each application scan in a portion of RAM, backed up by the
battery. On restoration of power' the retained data is loaded back
into the variables assigned as retained variables for use by the
application.

Diagnostic logs - The processor diagnostic logs are stored in the
portion of RAM backed by the battery.
The battery has a design life of 10 years when the processor module is
continually powered; for processor modules that are un-powered, the
design life is up to 6 months. Battery design life is based on operating at
a constant 25 ° C and low humidity. High humidity, temperature and
frequent power cycles will shorten the operational life of the battery.
Low Battery Alarm A variable is available in the Workbench that can be set up and report the
battery status. It will give an alarm and set a warning light on the
processor front panel when the battery voltage is low.
Disabling the Low Battery Alarm For applications that do not require Real Time Clock functionality, or
there are specific constraints, for example, the controller is in an
inaccessible location, that make it necessary to remove the battery when
the system is installed and set up, the battery failure alarm can be
disabled at the Workbench.
Rockwell Automation Publication ICSTT‐RM448I‐EN‐P ‐ May 2015 51