Stop Chart from Updating/Scrolling

[jhn.nguyen]

Hi,

I have a VI where periodically I need to prevent the chart from continually scrolling. The rate of scrolling is excessively high and I can't seem to either stop it or at least slow it. Currently the chart input is wired to a case structure which selects between acquiring data or using a default value. Using an event structure is not feasible as the section is embedded in a while loop and part of a larger application.

Thanks 

[Norbert_B]

From reading your post i have the impression that you are continuously writing single values to a waveform chart. If you do not want to update the chart continuously, change your code to "pause" writing to the chart on those situations. This will result in a "static" image of the chart until you resume writing to it.

hope this helps,

Norbert

PS: If you post your code, we can possibly give some further, better suggestions

[jhn.nguyen]

How would I implement a "pause"? I'd like to stop updating the graph continuously, but still require the remaining parts of the loop to continue. 

Thanks 

[altenbach]

You could put the chart terminal inside a case structure and it will only update if the case is true.

(Of course the time axis would be quite meaningless in this case).

[Dimitrios · Accepted solution]

I agree with Norbert B & altenbach

That's how is done briefly,

[Snively]

Ugh, thank you SO much.  Took forever to find this but it's EXACTLY what I was looking for.  You saved the day!

[SeanDonner]

I have this same requirement but the proposed solution will not work for me. The behavior I'm looking for is to have the chart to continue to plot new values but do NOT scroll me all the way to the front as soon as a new update comes in if my scrollbar position is anywhere but "present time". Essentially I want to defer a front panel update JUST for the chart when somebody scrolls to the left and reinstate the updates when they drag back to present time.

The best solution I can think of is to have two charts in a transparent tab control. When somebody hits a PAUSE button you take the history data from the chart that continues to update and you write it once to the chart in the other tab and then you switch the tab pages making the charts appear as one. When the PAUSE button is unchecked you switch tabs back to the updating chart. Although it works I'm creating duplicate copies of data which is non-ideal and this problem just feels like it has a simple solution via some property node that I have yet to find.

[Nathan-M]

This is a very interesting case, as I can definitely see where the behavior would be useful. While I haven't been able to create the functionality, I think I may have something that can help us get started figuring out the best way to do this. 

I started looking at events and event structures around a waveform chart, and I see that there's an event thrown when the scrollbar is moved of a chart. I'm thinking that we may be somehow able to write the data into a temporary location while this event is true, and then we can capture a mouse up event on the pane to trigger when to write the data back to the chart. 

I've attached a simple skeleton for this code which hides and then displays the plot legend when the scroll bar is moved. Obviously this is not the correct behavior, but if we can somehow create a temporary array and then alter this, I think we should be able to achieve functionality!

[SeanDonner]

Hi Nathan,

Could you upload a 2012 version of that VI so I can have a look?

Thanks!

[Nathan-M]

You know, I especially made a 2011 copy of it, but picked the wrong attachment when I made the last post. Here's the one that I meant to attach yesterday.