Experimental Physics and
Industrial Control System

"Kasemir, Kay via Tech-talk" <[email protected]> · Mon, 18 Nov 2019 14:51:05 +0000

Hi:

> ..PV for a pressure gauge which by nature covers many decades of values.
> I wanted to set up MEDM and ADEL values before starting to log the values to our archiver.
> Output is in exponential format, and i would like to monitor on e.g. 1 decimal independent of the exponent, it this possible.

I'm not aware of a good solution for efficiently displaying or archiving log-scale-type-PVs via MDEL respectively ADEL.
As you say, end users would like to see updates based on for example changes of "0.1", no matter if that's "0.1E-3" or "0.1E-5" on a log scale plot of vacuum pressure readings.
Sometimes the MDEL/ADEL is set to say "0.1E-5" because the reading happened to be in the E-5 range at the time, and then the vacuum improves to the E-6 range and MDEL/ADEL suppresses all updates.
So the only practical solution for archiving is to set ADEL=0, and store the value every few seconds to limit the amount of data. That's OK for the longer-term histor, but with vacuum readings you tend to care about some detail in vacuum excursions which start as a sharp spike, followed by exponential decay. With just a value every few seconds, you miss the initial spike detail.

Thanks,
Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System