Usage goal

When recovering from a power outage (where a “controlled shutdown” did not occur), the goal is to retain all runtime station data in volatile DRAM (Dynamic RAM) that had changed prior to power lost, that is, since the last station save to the JACE’s NVRAM, also known as “flash” memory. Changes apply to all normally persisted station data, including any changes to components, histories, and alarms.

Simply increasing the flash write frequency (for example upon each value change) is not viable because of eventual damage to flash memory components. Additionally, the latency of flash writes is significant; such writes may not complete if power is lost.

Replacing all flash memory in a controller with SRAM is cost prohibitive; however, a memory caching scheme using SRAM was developed. See the section “SRAM based solution”.

Usage goal

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