Experimental Physics and
Industrial Control System

That's a feature.

The archive stores changes​ in the value. We tend to not write the same value over and over if it didn't change.

When you plot a temperature setpoint and read back, the read back might change over time, but the setpoint  might have last been set by operators 3 weeks ago.

The plot would look silly if we don't show the setpoint, so we always start the plot with the last value at-or-before the start time as the initial value, and then draw a line until the next sample. If there is no next sample (value hasn't changed), you get a horizontal line since that value persisted all through the plot. Or you get a line that changes as the data changed.

In any case, that initial value is somewhat important, and that's why it's also included in the exported data, with the original time stamp.

-Kay

From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of Manoussakis, Adamandios via Tech-talk <tech-talk at aps.anl.gov>
Sent: Tuesday, May 4, 2021 1:15 PM
To: EPICS tech-talk <tech-talk at aps.anl.gov>
Subject: [EXTERNAL] Phoebus Data Browser CSV Export from Archiver, Extra Timestamp Issue