Re: [EXTERNAL] Re: How to archive PVs regularly even if they are not updating

[Ralph Lange via Tech-talk <tech-talk@aps.anl.gov>]

On Mon, 26 Sept 2022 at 17:13, Kasemir, Kay <kasemirk@ornl.gov> wrote:

MONITOR:  Channel uses monitor (for ADEL threshold) and tries to save every received value.

SCAN:  Channel uses monitor (for ADEL threshold) and then saves the most recently received value every SCAN period.

SCAN does not perform a get or get-callback every SCAN period, and it also doesn't save the time of when it was scanned.

Instead, it would for example scan once every 5 minutes, and then write whatever the most recently received sample was .. if it changed.

Pardon my archiver ignorance and thanks for the explanation.

Of course: SCAN mode intends to limit the number of samples written to file for fast-moving things with small ADEL. For rarely-moving things, it just blows up the file with redundant identical samples.

Sorry for the noise.

~Ralph