I’m not sure about the functionality. Currently exception values are also taken into account in the average trending. This can cause strange behavior, and I’m not sure this is supposed to happen.
Let’s say the normal values are between 0 and 10, and there’s an exception N/A with value -99.
The trend graph when zoomed out could show a line at -40, because it takes the -99 as value for calculating where it should display the average line.
For me personally, and for other users as well, this is not expected. I’m not convinced that exception values should be taken into account for calculating where the average trend line should be drawn.
However it could be that this is by design. Is it?
Exception values should never be taken into account for calculation of average trend entries. It’s currently under investigation why this is occurring.
To clarify: exception values should always be saved separately when they occur, regardless of the average time slot.
This also means that you should be wary of having parameters that toggle to or between exception values often. If these have average trending turned, the data set can become quite huge (we once encountered a case where we had a year’s worth of data with points at intervals < 1 min because exceptions kept occurring. This can cause both issues in saving and drawing the data.