The plot properties of the legend cannot be modified if the plot number is too large in a waveform chart

[William1225]

Hi,

There is something confusing me a lot recently.

Since I have to acqurie temperature from many channels, more than 300 channels, and I showed the data in a waveform chart.

When I'd like to modify the properties(such as plot width, plot color) of some plots(the number of the label more than 277), it failed. 

Have someone experienced the similar problem? Is there any workaround for this?

[RavensFan]

It worked for me when I tried to change the line width on  plot 295 on a waveform graph with 300 plots.

Do you get an error message?

Can you post a VI that demonstrates the problem?

[William1225]

Hi RavensFan,

Thanks to your prompt reply.

There is no error.

I thoght I'd attached the VI but I forgot

There are many wield things when I tried to change the plot properties.

For example, when I tried to uncheck the plot visibility, the lower plot number is fine, but higher failed. It changed the wrong plot.

The other video shows the failure of setting the line width.

[William1225]

Another failure results from adding plot manually.

[RavensFan]

I don't see anything in your VI where you are attempting to set the properties of the plots.

As for your other files, I can't open them.  Please attach them as regular .zip files.

[William1225]

Hi RavensFan,

I've downloaded my uploaded vi, there should be a simple code just to plot as following.

I've uploaded the zip files, there are videos demonstrating my problem.

Hope it is useful to let you know my problem 

[RavensFan]

Okay.  I see what you are describing.  The videos helped because I thought you were tryint go set properties programmatically which caused no problems for me.

I see you are trying to set properites by the right click menu.  It seems somewhat hit or miss as to whether those higher plots are able to be set.  Sometimes the visibility checkbox works, and often it didn't.

I can't tell how you are playing with the legened in your third video.

But overall, it seems like a bug.

[William1225]

Hi RavensFan,

Very thanks to your kind reply.

Exactly I can set the plot properties programatically, but fail when the user try to modify them in the UI.

I'd like to point out that it is not "sometimes" work.

When I uncheck or thicken the lower plots, it's fine.

When I uncheck or thicken the high plots, it's wrong. 

You can see when I thicken(uncheck) the plot 295, plot 39 becomes thick(disappear); when I thicken(uncheck) plot 299, plot 43 becomes thick(disappear).

It is very tricky, though it is a little stupid to plot so many plots in a chart.

I wonder if there is any workaround for this problem...

[RavensFan]

I had not noticed that other plots were changing when you tried changing the plot numbers.  Thank you for pointing that out.

My guess is that there is no work around for this, that it is a bug.  And my specualation is that it is related to the limits of a U8 data type.  When you say #43 changes when you work on #299, the difference between those two numbers is 256..  Likewise 295 to 39.  Try doing a graph with more than 512 plots and see if a plot like 550 winds up affecting plot 38.  It seems like the number you pick rolls over at 256.

Hopefully someone at NI can jump in here and confirm this bug and will submit a CAR for it.

As you said, the work around is probably not to have a chart with so many plots in it.

[hans17]

I ran into this chart legend bug in my application and made a test VI before finding this thread.  Turns out that using the chart legend to change properties of the 520th plot does affect the 264th plot instead.  Agree with Ben that this looks like a U8 bug.

The bug only occurs after the legend is scrolled down so that the plot shown at the top of the legend is the 257th or later.  If Plot 256 is at the top of the legend, altering the charting plot properties via the legend works as expected for all the shown items.  For example, you can successfully change properties for Plot 275.  But if Plot 257 is at the top and the legend is used to alter the properties of Plot 257 or greater, the properties are applied to the plot that is 256 items earlier in the list. 

My test VI is attached.  You can adjust the # Of Plots to Create and then change the Charting State to Initialize Chart to test different numbers of plots.  The Charting State will automatically change to Charting On.  Click on the legend's plot visible check boxes and see which plot appears or disappears.

I have >500 variables that my users would like to see in the chart.  It'd be great if I didn't have to implement a selection scheme so they can select different variables to send to the chart.  One of the cool features of the chart is that when something odd happens in our complex system, they can select pertinent variables in the legend and see or save the plot data in the chart history.

I'm using LabVIEW 2015.  Has this bug has been fixed since then? 

If not, NI could you please open a CAR as Ben suggested?