Power chart, are trends always interpolated?

Ignition Early Access
,
1

As I am trending iOT sensors I would like to view the pens in a digital style.

The measurements arrive quite seldom, so if i want to watch the last 24 hours, and i only have 8 measurements, the interpolation makes the trend useless (for my case).

I see when using bindings in general in Perspective, one has the historical binding option “asStored”. Then by creating two trends from the same series in a time series chart one can atleast see the points (still missing the digital style though):

The power chart does not have an option for either digital style, or asstored. Am I missing something, or maybe this should be a feature request?

image
image975×502 39.9 KB

Edit:
One more thing. What is the point of the “scatter option”, if the historical data is always interpolated? This will always result in a “scatter” point on all interpolated times

2

In your ‘pens’ objects, change the interpolation type to ‘curveStepAfter’

image
image367×688 26.5 KB

2 Likes
3

That was easier than expected :slight_smile: thanks alot!

1 Like
4

A prerequisite for using curvestepAfter, is that the measurement has to bee stored with a discrete Deadband Style:
image
If not you get these:

image
image408×716 37.5 KB

7 Likes
5

Thanks for the tip on the “Discrete” prerequisite. It help me today.

Can you add a caption to the red ellipse images above? What are we supposed to learn from them?

6

Note that one can also change the config > pointCount property on the Power Chart component to -1. That will return only as-stored values and present them in a manner consistent with step interpolation. That works even when the tag history has not been configured using discrete as the deadband style and does not seem to be affected by the interpolation setting on the pen configuration.

6 Likes