Waveform chart does not display when dt = 0.01

[Bart Kampers]

Hello,

I noticed something strange when using the waveform chart. For a test I generated some waveforms with 250,000 elements and displayed them in a Waveform chart. This works OK when dt is 0.1 or 0.001. But when dt = 0.01 the chart shows no data. The time axis runs from 06:04:09.990 to 06:08:19.980 while the data in the waveform is between 06:00:00.000 and 12:56:40.000. The x-scaling of the chart is automatic.

Has anyone any idea what is happening here?

Kind regards,

Bart.

[RikPrins]

Hi Bart,

What version of LabVIEW do you use? Is it possible for you to post an example VI? I could not reproduce this in LabVIEW 8.2.

Regards,

RikP - National Instruments Applications Engineering

[Bart Kampers]

Hello Rik,

I attached a VI that does about the same as I described. It is not exactly the same example since that one has changed several times.

This VI generates a TDMS file containing a waveform. Then it reads the file and shows the contents in a waveform chart.  I now see that the time axis never shows the complete period from the waveform, whatever data generated.

I use LabVIEW 8.2 also.

Hope you can give me some clue.

Thanks in advance,

Bart.

[Dennis_Knutson]

What I see is the exact same data on both indicators. Not sure why you are using a graph for one and a chart for the other. The graph is set to ignore the time stamp. Uncheck this and Xscale>Loose Fit and you should see the data in the same format on both. Or, use a graph instead of a chart on the read data. A chart does not have the option to ignore Time Stamp.

[Bart Kampers]

There is no special reaseon to use a chart, I was just trying some things.

I replaced the chart by a graph and this works fine. But I don't understand your fisrt solution.

Neither the graph nor the chart were set to ignore the time stamp, and yes the chart doe have this option. Checking or unchecking it doe not make any difference. Further I cannot find anything about "loose fit". Shoud it be in the  in the scale tab?

[Dennis_Knutson]

I don't have Ignore Time Stamp on a chart in any version of LabVIEW. Where do you see that?

Loose Fit is an option under both X Scale and Y Scale when you right click on the graph/chart.

[Bart Kampers]

The "loose fit" option is grayed out for the x-scale on a chart.

I found the "ignore time stamp" in the properties scale tab.

I still use LabVIEW 8.2. Ther must be a reason why our properties for charts are different.

[Dennis_Knutson]

I learned something new today. Thanks. I assumed that since the Ignore Time Stamp was not available by right clicking on the chart, it would not be available on the properties menu.