How Clear a WaveForm Chart Programmatically?

Hi LabView Masters!
Can I Clear a WaveForm Chart Programmatically?
I know that I can clear the chart clicking with the mouse, but I need to
clear it when a particular variable is high. (Programmatically)
I have been testing the Attribute Node but I didn't got it.
Thanks in advance for your help!.
Francisco Javier Fernandez Luna
Ingeniero Tec. Industrial en Electronica.
Tel: 619 81 98 31
E-mail:[email protected]
ó [email protected]
"Let's make things better" (PHILIPS)

try to use property node of the chart and connect an empty array to
"history data" field
Paco Luna a écrit dans l'article
<01beae87$7fe22e60$[email protected]>...
> Hi LabView Masters!
>
> Can I Clear a WaveForm Chart Programmatically?
> I know that I can clear the chart clicking with the mouse, but I need to
> clear it when a particular variable is high. (Programmatically)
>
> I have been testing the Attribute Node but I didn't got it.
>
> Thanks in advance for your help!.
> --
> Francisco Javier Fernandez Luna
> Ingeniero Tec. Industrial en Electronica.
> Tel: 619 81 98 31
> E-mail:[email protected]
> ó [email protected]
>
> "Let's make things better" (PHILIPS)
>

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i'm using LV7.0 and what i need to do is to be able to set the time frame or range of a waveform chart programmatically before i start taking and plotting data. sometimes this window needs to be 30s wide and sometimes it needs to be 24 hrs wide. (in the first reference, i need the chart to fill up with 30s of historical data then the whole chart scrolls with each new data point). the data acquisition records data at a rate of once per second. i've tried to use the chart properties of XScale.offset, XScale.Range.Minimum and XScale.Range.Maximum but no matter what i do the time-stamp on the x-axis is always "00:00:00 PM" and "MM/DD/YYYY" even though values are seen being plotted on the right side of the chart as expected.
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Okay, there seems to be some confusion here -- the X axis values are of type double, but they can be represented in the HH:MMS MMD:YYYY format if you want in which case it interprets the floating point as the number of seconds since 6pm Dec 31, 1903.
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Your acquisition needs to run in parallel with your main loop. You should also use a queue or notifier to send that parallel process commands (like to stop). I would use a User Event to send the data from your aquisition to your main loop's event structure. You can then update the chart inside of the event structure.
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You need to check the update mode of your chart.
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The waveform chart maintains a history of data, or buffer, from previous updates. Right-click the chart and select Chart History Length from the shortcut menu to configure the buffer. The default chart history length for a waveform chart is 1,024 data points. The frequency at which you send data to the chart determines how often the chart redraws.
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Clearing a waveform chart

Hello!
Can someone explain how to re-set a waveform chart to initialize to 0
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Adrian,
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Welcome.
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> I am not understanding the Memory allocation concept in chart. When it
> will be happened? If it is in run time, I am getting the exception
> before running the application itself. Can you help me on this?
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Hi,
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Sorry, I made what you have told me:
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Waveform charts can hold different data types (they are polymorphic), such as DBL or 1D-array of DBL. When you want to set the history, you need a 1D DBL or 2D DBL respectivily. The correct data type is part of the 'strict type', I guess you will get the default instance if you use the non-strict (generic) type.
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Hi rockybooth,
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RavensFan, thanks for your response. It actually worked for me. Although, you answered my question already, but just allow me to ask one more thing under this thread. If I want a flat line known as a "baseline" a numerically controlled/adjusted value to appear on the same Waveform Chart that my incoming signal(s) is/are plotting, how do I imposed or put that "baseline" on the same waveform chart? The "baseline" is only acting the purpose for comparison or threshold?
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How Clear a WaveForm Chart Programmatically?

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