Waveform chart auto clear

Hello,
I am doing data acquisition with labview and showing it on a waveform chart. I wish to generate an excel file with two columns : time and amplitude automatically after the vi finishs. But everytime I start a new acquisition, the x-axis (time-axis) start from the previous time value and when the excel file is generated, the time doesn't start from 0. I know it is possible to perform"clear chart" from the data operation by right clicking the chart on the front panel, but it is troublesome to do so everytime. Is there any other way to clear the time-axis to 0 for every new launch of the vi?
Solved!
Go to Solution.

Thanks for the solution. I did this :
but the excel generated doesn't save all the data from the waveform chart. It only save a short amount of data. Why is this so? Is there anyway to save all of the data?

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How can I display more than 1 loop iteraction in a waveform chart?

Using DAQmx, I am inputting a signal at a rate of 10k with 1k samples inside a while loop. I want the first 3 seconds of data to display on a waveform chart without having to change the rate or number of samples. Is there a way to stop the waveform chart from clearing after every loop iteration so that I can display more than 0.1sec of data? Thank you for any help you can provide!

The default history length of a chart is 1024. To make it longer is a right click option.

How to clear waveform chart

How i can clear a waveform chart with dynamic datas? The normal procedure with handover a empty array doesnt work.
Uwe Augst
Muehlbauer AG
Germany

Hi,
here´s a small example with a property node (Historie), everytime you restart that VI, first the chart is cleaned up and than refilled again.
Hope this helps,
AlexMessage Edited by Alex R on 05-03-2005 11:18 AM
Attachments:
Clear Waveform-Chart.vi ‏21 KB

Clear waveform chart history if dynamic 1D data is used

I am new to Labview and am using a Waveform Chart. To clear this I need to supply an empty array. I have done this with scalar inputs, but in this present case, the input to the chart is a bundle of 1-D array of dynamic data. I cannot figure out how to create a suitable empty array of type 1D array of dynamic data to initialize the plot (wire to the History).
It seems like there should be a better (easier) way of clearing the plot...
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Solved!
Go to Solution.

Hi rockybooth,
right click on the connector to the history property and select "create constant". You should get what you need.
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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)
>

Auto update waveform chart error

Hi all!
I have come across the problem when working on my VI. As you can see from the VI that I have attached, there is a waveform graph on the front panel for data acquisition. The value shown right now is from time, 00:00:00 to 00:05:00 (0-5minutes).
The problem that I am faced right now is, everytime when I hit the run button, LABVIEW seems to automatically change my time value to some sort of generic time. What I want to accomplish here is that, I want to acquire data on the waveform graph from time 0 to 5 minutes. Also, I would like to specify the increments myself. For example on the time scale (x-axis) from 0-5 minuntes, I would like a 30 seconds interval between them. How do I actually accomplish it?
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Thanks for any help!
Jlam
Attachments:
PDaq- Modified_07-08-2010.vi ‏61 KB

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Clearing a waveform chart

Hello!
Can someone explain how to re-set a waveform chart to initialize to 0
at the start of the run of the VI.
I notice one example where a zero array is input...
but this looks like overkill.
Is there an easier way.
Thanks,
Adrian

Adrian,
It's really simple. Just create a property node or reference to the chart, and select the history. Then, just wire a constant (easiest to create a constant from the node itself) which is empty, and voila - an initialized chart.
Good luck, and let us know how you do.

Saving array data from a waveform chart

I am using a CRIO 9004 and a 9237 bridge module to measure some strains from strain gauges. I've got one timed loop that reads the DMA FIFO and puts the arrays of values (16 data points, 4 per channel) into a queue. In the consumer timed loop a For loop scales the binary data, auto indexes it into arrays, then the arrays are merged into a 2D array for the four channels displayed on a waveform chart . Everytime the consumer loop runs it indexes 4 data points (per channel) yet the waveform chart plots them in a consecutive manner and doesn't overwrite the previous four. If I convert the arrays to waveform arrays I don't see anything on the waveform chart.
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I've attached my host vi and front panel screenshot.

Hope they appear attached this time.
Attachments:
Basic DMA (Host).vi ‏444 KB
screenshot2.jpg ‏113 KB

GR/IR not auto clear in system

Hi All,
GR/IR not auto clear in system
Normally every week end the system automatically clears the open items in f.13, But this time it has not clear the open items
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Hi All,
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Combining 2 readings into a waveform chart/graph displaying continuous readings of data from different sources

Hi,
In the file
(Serial Read and Write to .tdms & Compare on Graph – test.vi) I am trying
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The readings are taken in by the program
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Thanks in Advance.
Best Regards,
Akhil
Kumar Meesala (Mr.)
Year
4 | Undergrad | Mechanical Engineering
National
University of Singapore
Email:
[email protected]
Mobile:
(+65) 9326 7069
Solved!
Go to Solution.
Attachments:
Serial Read and Write to .tdms & Compare on Graph - test.vi ‏58 KB
Teraterm - Results.xlsx ‏593 KB

Dear GerdW,
I'm sorry again about the misspelling your nick.
I tried connecting a waveform chart to the two terminals (speed from the DAQ and speed from the excel file) but I was unable to get the connection right. I understand that charts are used for readings which are equally spaced out, whereas XY graphs are used when the readings are not be spaced out uniformly. But I am unable to wire the connections correctly.
Actually the DAQ device continuously sends out data through the serial port. So I would not run out of data . Are you referring to the data coming from the DAQ device or the excel file? I actually have not thought of what would happen when the excel file would run out of values I am just hoping for the software to run till then for now
I have cleared up the wires as well Thanks for your help.
Best Regards,
Akhil Kumar Meesala (Mr.)
Year 4 | Undergrad | Mechanical Engineering
National University
of Singapore
Email: [email protected]
Mobile: (+65) 9326 7069
Attachments:
Get Excel Values.vi ‏25 KB
read_excel_values.llb ‏201 KB
Serial Read and Write to .tdms & Compare on Graph - test.vi ‏79 KB

Any alternate solution to using Waveform Chart Property Nodes 'ActPlot', 'Plot.Visible' for mulit-plot color problem on PDA?

Hello,
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Mobile.
Thanks & Regards,
Subhashini
Attachments:
BundleSignals_Select_Desktop1.vi ‏25 KB
BundleSignals_PDA.zip ‏26 KB

Unfortunately the only alternative to using property nodes is to set the properties manually on the development environement. The limited size of memory does limit us in terms of features for the module.
Mehak D.

Waveform Chart - How to set X scale time.

I have a Waveform chart (v6.1) and I want it to display 30 seconds of data. What is the correlation between the Time History buffer and the Time inputed on the X-scale. The X-scale format is set to Relative Time. I set the initial time to 0:00. The input data is coming in at 20 samples/sec also. How do I set up the chart to show only 30 sec of data.

You can turn Auto scale off and set the left value to 0 and right value to 0:30.
A second method is to set the chart history length to 600 (20 samples per second * 30 seconds). Setting the chart history length can only be done at design time.
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Waldemar
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Don't forget to give Kudos to good answers and/or questions

Why does AI Read(Asynchronous).vi cause the waveform chart to not display any history ?

I trying to create a strip chart for 16 channels that will require displaying 10-20 minutes of data.It also starts a separate vi to set gains and offsets while displaying the data. Using AI Read.vi uses 100% of the CPU so the second vi does not run. But using AI Read (async).vi allows the second vi to run, but causes the waveform chart to not display the history? I'm using LabView version 6.0.2.

Hi Waynes World,
I have a couple of questions that may help us solve this issue...
1) If you are modifying one of our example programs, which one did you start with?
2) What kind of analog input are you doing? Buffered? Finite or continuous?
3) Have you tried increasing the buffer size of the strip chart? This will allow the chart to store more data in it.
4) When you use the Async VI, and when you are using the other, can you describe how the strip chart is showing the data... does the data in the chart keep growing and growing... or does it clear itself and start over when the pine reaches the end?
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Horizontal scrollbar of waveform chart in tab page resets to end when tab page switched

I've got a VI in LV 2012 with a chart in one of two pages of a tab control. Whether compiled to an executable or not, when the waveform chart contains data that is no longer being updated and the x-axis range doesn't show the last point of data, the horizontal scroll bar auto-adjusts to show that last point if you switch pages (back to the chart) on the tab control. I've tried turning off Autoscaling but that doesn't stop the effect.
Additional issues:
On some of these attempts at reproducing this, the X-Axis will even change scaling, zooming in on the data.
When data is pushed left by this bug to allow displaying the furthest data point, if the leftmost area of the chart was blank before the data was pushed left, the data pushed left into the formerly blank area will not be displayed. This happened only when the X-Axis was manually autoscaled prior to pushing the data off the right edge of the chart, and only if the x-axis scale was not changed. If the tab pages are again switched at this point away and back to the chart, the data re-appears.
The chart is a stacked plot if that makes a difference, Also, the tab control is not linked to any event handlers.
Also, the scrollbar works fine if you scroll such that the rightmost data points are on the chart along with blank area to the right, whether there is more data off the left edge of the chart or not.
Last, the Y-Axis of each stacked plot is unaffected by any of this.
I hope this isn't a duplicate - I didn't find it in the forums.
Thanks,
Erik
Attachments:
Flaw Demo.vi ‏120 KB

Alex,
Thanks for the quick response on this. Again, the charts are awesome except for these minor fiddling details. Sorry about the terminology confusion - I didn't find anything in the Help system naming the legend buttons, and unfortunately I can't edit the prior post. When I said "AutoScale LocK" I meant "Scale Lock", and "AutoScale Once" I meant "Autoscale".
Here are the issues, hopefully clarified:
1. If any chart elements have Scale Lock set, pressing the AutoScale button for any plot causes these other plots to autoscale as well. Note these are not plots with multiple Y scales, they're stacked plots with separate y-scales for each plot. Changing the "Advanced->Auto Adjust Scales" parameter had no effect on this issue.
2. If none of the chart elements have Scale Lock set in the scale legend, pressing the Autoscale button for the X-Axis has no effect if the x-axis was previously set to show all the data history but then panned such that some data falls of either side of the chart.
This may have been confusing, so here's a breakdown of the steps to re-produce the problem using the VI I previously attached.
a. AutoScale all elements of the chart, and turn off Scale Lock on all elements
b. Move the data to the right in the chart, so the left half of the chart area has no data (e.g., set the X-Axis range to -5 to 6 seconds)
c. Press the X-Axis AutoScale button. The X-Axis range will not change from where it was in (b).
3. The Y-Axis will also auto-scale when returning to the Chart tab if Scale Lock is enabled for the plot with the fix for the x-axis scale in place (restoring the Xscale.Range parameters from a local variable). If the fix is not performed, this doesn't happen.
4. Pressing the Scale Lock button on one of the plots causes the X-Axis scale to be lost IF there is data past the maximum displayed X-Axis range. It looks like it set the X-Axis to the same problem range as before the fix was in place. I don't know how to build an event case for this, except for possibly "Mousedown?".
One more:
5. Enabling Scale Lock on any plot auto-scales any other plot that has Scale Lock enabled (assuming the user changed the Y-Axis range from the previously auto-scalled range). Obviously this is linked to #1 above, but worth noting.
Thanks again, Alex!
Erik

Problem with waveform chart

Hello friends.
I'm in learning lab view and have some questions.
I get a signal with an Analog to Digital converter (an Atmega 32) and send data to com port .
I convert my data to real value in voltage and time .
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By Increase of frequency , waveform chart can not draw my data Clearly.
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Attachments:
t4.vi ‏13 KB

Interfacing with hardware is seldom easy. That is why I lean toward NI stuff since they have made there stuff resonably simple and they have good supprt.
When interfacing with hardware from others, we have to look fo rthe manufacuer of the hardware to provide enough support to get started.
So I suggest you contact whoever makes your device and get some examples from them.
Hopefully they have heard of LV and have drivers.
Otherwise, ther is no guarentee it will be possible.
If English is not your primary language, plese feel free to post in both English and your native language. We have contributors that can handle most languages so do not let English get in the way.
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Ben Rayner
I am currently active on.. MainStream Preppers
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Waveform chart auto clear

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