Hello,
When I open a trend (both real time and average trending enabled) and export it to csv, I see something like this :
from what I understand, when we export a trend to a csv, it captures data whenever there is a change in the value irrespective of the timestamps, correct ?
Or are these timestamps somehow related to how frequently the driver polls this parameter ?
Hello Arunkrishna,
Yes the change in parameter results in a new trend point with the value and the time this happend.
In a way they are related to the driver poll cycle. If you poll every minute you will see that there is always 1 or more minutes between value changes en thus the timestamps. More minutes as a value didn't change to the previous poll cycle.
But sets are not limited to poll cycle alone, this can also be the result of a QAction, Automation script, manual set, ...
Note that the behavior is different for average data (where you’ll have an averaged point at every interval).
The time the value changes, the actual set of the parameter.
In some cases it could take a couple of seconds after the start of the poll cycle before the value is received and set.
Thanks Dries, in that case, which timestamps will be written to the database ? The time when the driver polls or the time when the value changes ?