Chart digital display bug

[ceties]

Hi,

I am using chart with stacked plots and digital display for each of those stacked plots. There seems to be some update bug since if I move the display on the chart weird things start happening. The chart stops to update some plots and also artifacts appear. When I hide the digital display all seems to work as expected. What is the problem? Is it a bug? Is there some work around or do I have to code my own digital display?

I made a short video to show the problem.

[ceties]

VI to demonstrate the problem attached

[dobarni]

Hi Ceties,

I couldn't find any bug report on the issue you have noticed, however it chart updates seem to work fine in Labview 2010 version (and Win7). I also managed to see the behavior you described when running the example code with Labview 2009 (and Win XP).

Can you run your application with Labview 2010 as well?

Regards,

Barna D.

National Instruments.

[ceties]

Hi Barna,

I was investigating a bit more. The update mode seems to be the key. If the chart is set to strip chart it behaves as expected. If it is set to scope chart and sweep chart problems appeared. I don't plan to switch to LV 2010. Could you test all three modes of the chart and in case it doesn't work correctly in 2010 could you file a CAR?

[dobarni]

Hi Ceties,

Actually I've noticed yesterday that different updated modes have different behavior of the chart. So I checked all combinations (update modes with/without digital display) on both LabVIEW versions - sorry for not mentioning that yesterday- and the result was what I posted previously. In Labview 2009 I was able to reproduce the issue, while in Labview 2010 version all update modes were displaying data correctly.

Anyway thanks for pointing to the chart update modes, so one workaround is to use Strip chart update mode under Labview 2009.

Regards,

Barna D.

National Instruments

[ceties]

I upgraded to LV 2010 and the above mentioned problem is still present. The bottom plot doesn't stop updating but i tis still apparent that there is some refresh/update problems. You can see in the video that some parts of the data are missing. As soon as I hide the digital display the graph refreshes properly without those ‘‘fringes‘‘. I think this deserves deeper investigation.

http://screencast.com/t/OGZjZTk1

[ceties]

After I wrote my own implementation of the digital displays I realized that this problem appears also if I use separate controls and place them on the graph. Really annoying. The workaround I found, whether using the native charts digital display or your own version, is to force the graph to refresh. This surprisingly cannot be achieved by the method chart.refresh which doesn't help but by toggling for example Legend.ScrolBarVisible. If you toggle this property after writing data into the graph this annoying bug disappears. Other usable properies for this are: chart.visible, chart.updatemode, chart.plot.visible, chart.plot.color

LV 2010

[dobarni]

Hi Ceties,

I was able to reproduce the behavior you were seeing, so I reported the bug to the developers (CAR#252270).

I am sorry and I understand that you are frustrated, that things are not perfect. And thanks to bringing it to our attention so we can improve Labview environment. 

THANK YOU!

Regards,

Barna D.

National Instruments

[ceties]

Will this be fixed in LV2011?

[ceties]

I am asking because it is not even listed here: http://zone.ni.com/devzone/cda/tut/p/id/11869 which makes me quite upset. The digital displays+chart really need some additional work. Simply by moving the display on the chart (instead of having it next to it) the CPU load is tripled!