Goals and Symptoms

A customer is wanting to setup high speed logging continuously on a 7550/7650 meter and is concerned that the flash memory will fail prematurely.

Causes and Fixes

The 7550/7650 firmware greater than V320 have a built in flash throttling mechanism to prevent over-erase conditions on the flash memory. The meter buffers all logs in DRAM before writing them down to flash. The system is designed to allow every data recorder and waveform recorder to write to flash once every 10 minutes (these write credits accumulate). In the case of high-speed logging, the DRAM continues to log the data, and the meter backs them up to flash whenever a credit is available.
Continuous high speed logging results in flash writes every 10 minutes, allowing the meter to survive for a very long time.

These credits are unique to each data and waveform recorder. If one data recorder is logging every 100ms, it will be throttled to 10 minute writes. Other data recorders triggering periodically (eg 15 minute intervals) will be saved immediately.

Note: This flash write delay does not prevent the logs from being downloaded via comms, there is no noticable effect to software or the user in general.

However, tt is not recommended to use the meter in this manner as it will shorten the hardware life span compared to a meter only using high speed logging during power quality conditions and other short term events.