The SRAM is a battery-buffered, nonvolatile RAM and is used for the retain/persistent and the %M variables. If a battery is inserted into the processor module, the data stored in the SRAM will not get lost during a power-down cycle.
During PLC startup, the SRAM will be deleted automatically if no or an empty battery is inserted into the processor module. In this case the information
ABBInitSram_SetupMemory : SRAM cleared
and the warning
Retain size in config changed, or retain area got corrupted
are written into the log file.