Flash Memory Operation - GE PACSystems RX7i Reference Manual

4.6

Flash Memory Operation

The CPU stores the current configuration and application in user memory (either battery-backed RAM or
non-volatile user memory, depending on the CPU model). You can also store the Logic, Hardware
Configuration, and Reference Data into non-volatile flash memory. The PACSystems CPU provides
enough flash memory to hold all of user space, all reference tables that aren't counted against user
space, and any overhead required. For details on which items count against user memory space, refer to
Appendix B.
By default, the CPU reads program logic and configuration, and reference table data from user memory
at power-up. However, logic/configuration and reference tables can each be configured to always read
from flash or conditionally read from flash. To configure these parameters in the programming software,
select the CPU's Settings tab in Hardware Configuration.
If logic/configuration and/or reference tables are configured for conditional power-up from flash, these
items are restored from flash to user memory when the user memory is corrupted or was not preserved
(for example, the memory backup battery or Energy Pack is not installed or not operational). If
logic/configuration and/or reference memory are configured for conditional power-up from flash and
user memory has been preserved, no flash operation will occur.
If logic/configuration and/or reference tables are configured to always power up from flash, these items
are restored from flash to user memory regardless of the state of the user memory.
Note: If any component (logic/configuration or reference tables) is read from flash, OEM-mode and
passwords are also read from flash.
In addition to configuring where the CPU obtains logic, configuration, and data during power-up, the
programming software provides the following flash operations:
▪
Write a copy of the current configuration, application program, and reference tables (excluding
overrides) to flash memory. Note that a write-to-flash operation causes all components to be stored
to flash.
▪
Read a previously stored configuration and application program, and/or reference table values from
flash into user memory.
▪
Verify that flash and user memory contain identical data.
▪
Clear flash contents.
Flash read and write operations copy the contents of flash memory or user memory as individual files.
The programming software displays the progress of the copy operation and allows you to cancel a flash
read or write operation during the copy process instead of waiting for the entire transfer process to
complete. The entire user memory image must be successfully transferred for the flash copy to be
considered successful. If an entire write-to-flash transfer is not completed due to canceling, power cycle,
or some other intervention, the CPU will clear flash memory. Similarly, if a read-from-flash transfer is
interrupted, user memory will be cleared.
GFK-2222AD April 2018
Chapter 4. CPU Operation
153