Easy Chart Axes (Historical)

Is it possible to display all the trends at once, but only show a single scale (y-axis) based on the users selection (e.g. the user clicks on one of the trend lines)?

In addition, it would be nice if the user could select a moment of time (maybe represented by a vertical line through the graph). Then all of the values for the different trends could be displayed via a mouse over for that particular time.


There isn’t a great way to only use one axis. The chart is set up to easily display one axis for each set of pens you link to it, but with scripting you could set every pen to the same axis. But I think this is not exactly what you are looking for.

If you right-click on the easy chart (in a client or preview mode), you can select Mode -> X-trace and after that clicking on the graph will create a vertical line that lists the data points for the closest time you clicked on.

I hope that helps,

How can 2 vertical lines be displayed on an Easy Chart? Either using Mark or X-Trace

There is currently no way to have multiple X-traces, but we do have a feature request for this.

Any update on this feature request?

No, there isn’t - it’s been sitting since it was originally filed at a low priority level.

If you’d like it to be completed, I would recommend heading over to ideas.inductiveautomation.com, or, since he can probably do it faster than we will, you could see whether @pturmel might add it to his (excellent) NoteChart module.

Thanks, just upvoted.

For anyone wanting this:

I have not tried 3rd party modules such as NoteChart, will give it a go when I get some time!

I just thought of a way to do this with a minor addition to NoteChart – extension functions for the X-Trace timestamp string to display, and for the trace value to display. (The latter per pen.) To display a “differential mode”, the user would cache the pen values and timestamp for the reference location (with a highlight-colored “note” to show the reference witness line), and generate the deltas to display when the extension functions are called during painting.

The user would have to maintain state somewhere as to whether to display deltas or fallback to regular X-Trace. I’ll have the paint routine fallback to the regular text if the extension functions return None.


So, who wants to test this beta for me? My calendar is full tomorrow, and dinner today is already late… /:

(It does load and list the new extension functions in the designer. I haven’t done any functional testing beyond that.)