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.

Similar Messages

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)
>

How do i clear a waveform chart after i press stop?

I attached what I have so far.
I'm taking readings from 3 thermocouples simultaniously.
I then graph and log the data in real time.
I would like it if after i press stop, the graph resets. Then when i press start, the graph starts from the beginning.
Any ideas how to do this?
Cory K
Attachments:
Test1.vi ‏143 KB

On the False side of your measure case, use a Property Node for each chart. Property should be History Data, set it to write, and wire an empty array to it. This will clear the graph. I'd also use a shift register wired to a boolean so that you don't keep writing to the properties. Set the boolean to true on the True side of your measure case.
Message Edited by Mythilt on 05-27-2008 12:39 PM
Jon D
Certified LabVIEW Developer.
Attachments:
Test1[1]d.png ‏17 KB

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

Open Vi object reference waveform chart

Hi, I'd like change a property of an indicator in a VI from another VI (In particular i want to clear a Waveform Chart) I used Open VI Object Reference but i am not able to access to History Data. How can I do?
Solved!
Go to Solution.
Attachments:
ClearChart.vi ‏7 KB
test.vi ‏12 KB

Sorry, I made what you have told me:
now i have this error:
why? If you have implemented a correct Vi can you give me it please?
Thanks!
Attachments:
ClearChart.vi ‏14 KB
test.vi ‏12 KB

Strictly typed refnum vs normal refnum for a waveform chart

I know that one way of clearing a waveform chart is to write an empty array to the 'history' property of the charts property node. The help file for this states: "use strictly typed refnums when reading this properrty"
I am looking at a program coded in LV 8.6
a number of control refnums are carried around in an array (so strict typed)
in some cases (but not all) the programmer used "to more specific class" to designate a waveform class when writing to properties for scaling the Y-axis, etc. Other times this is not done(?)
We are now having an issue which appears to be that the chart is re-initialized when dynamically rescaled (I am not sure if that is what is going on, but that is what it looks like).
It looks like when the chart is dynamically rescaled the previously acquired data is gone and the chart starts populating fresh.
Haven't figured out what is causing this, and I am wondering if strict type refnums vs generic refnums may be a factor?
Lawrence M. David Jr.
Certified LabVIEW Architect
cell: 516.819.9711
http://www.aleconsultants.com
[email protected]

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.
But if this is releated to your problem, I can't even guess.
Felix
www.aescusoft.de
My latest community nugget on producer/consumer design
My current blog: A journey through uml

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?

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...
Thanks for any ideas.
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.
Hope it helps.
Mike

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.

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
to integrate the following two waveforms into a single waveform: Realtime
reading and Waveform chart (open vi to see). Both of them display speed vs time
but from different outputs. One comes from an excel file (Teraterm – Results.xlsx
– sheet 4, (column 3:row 4) to (column 3:row 1878)) and the other comes from
the Serial input which is in Hex format and is split to get the various readings
of speed, voltage etc. I have already wired speed to a variety of waveform
outputs, but all result in broken wires.
The readings are taken in by the program
and but I am unable to wire the two readings together into one graph.
Please do let me know as to how can I make this work.
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

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.
If I pass the 2D array of data to a array indicator inside or outside the consumer loop I get only 16 data points. I want to save the information that appears on the waveform chart after the consumer loop but because I'm not using waveform data type I can't use the write waveforms to file vi. The waveform chart history buffer has been set to 195360.
Idealy we will run the four channels for 120 seconds charting the data and saving the data. The minimum data rate is 1613kS/s (403 per channel) The data can be saved after the loops have finished gathering and processing or while they are running. I noticed when I tried to write to TDMS it slowed the consumer down. Same thing if I use a shift register with the volume of data.
I suspect I'm not sending data to the chart in the correct manner ( usualy takes two attempts to "clear chart" using shortcut menu). I'm not too familiar with timed loops /producer consumer loops and just tried to put something together based on examples.
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

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

Hello,
    On a waveform chart, 4 signals need to be plotted based on the status of 4 boolean inputs. Eg. if the first boolean input is true, the first signal needs
to be visible on the waveform chart; if the first boolean input is false, the first signal should not be visible on the waveform chart and so on. This can be
done on LabVIEW desktop using the Waveform Chart Property Nodes 'ActPlot', 'Plot.Visible' - a sample VI "BundleSignals_Select_Desktop.vi" is attached for
reference.
    But on PDA, since the Waveform Chart Property Nodes 'ActPlot', 'Plot.Visible' are not supported, some other method has to be used. I have done the
selection/de-selection of these signals using 'Insert', 'Delete' array functions as shown in the attached VIs "BundleSignals_PDA.zip" which works, but the
problem is that the colour of these signals do not work as desired when the selection/de-selection of these signals is done - It is required that the first
signal should always appear in White color, the second signal should always appear in Red color, the third always in Green color & the fourth always in Blue
color.
    I hope i have made myself clear of the problem. Has anyone faced this problem before & is there a solution?
Note: Version of LabVIEW that we are using: LabVIEW 8.5 Professional Development System for Windows Vista/XP/2000 and LabVIEW 8.5 PDA Module for Windows
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.

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?
I think this issue is rooted in how the buffer is being used with the two different AI Reads and how it returns data to the chart.
On a side note, have you considered upgrading to a newer version of LabVIEW? Our latest versions of LabVIEW come with many new features and it is signifigantly easier to use.

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 .
But i have problem with show wave form in different frequency .
By Increase of frequency , waveform chart can not draw my data Clearly.
What i do to show data in different frequency ?
Thanks .
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.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Impossible to clear a waveform inside a cluster...? LabVIEW quirk?

I want to erase the chart history of a chart inside of a cluster. This seems apparently impossible to do. The code takes two minutes to see what I'm talking about--sorry no predone LabVIEW code.
Create cluster
Create waveform chart in cluster
Create a waveform chart outside of the cluster
Switch to diagram:
Create cluster property node
Select AllObjs[]
Create for loop
Wire AllObjs[] output to for loop (leave indexing enabled)
Inside for loop:
Drag to diagram: "class specifier constant", under app control
Select VI Server class and choose:
Generic > GObject > Control > GraphChart > WaveformChart
Drag to diagram: "to more specific class", under app control
Wire "class specifier co
nstant" to top node of "to more specific class"
Wire indexed reference from AllObjs[] to left 'reference'
node of "to more specific class"
Drage to diagram property node, under app control
Wire output terminal of "to more specific class" to property node.
Create property node from Waveform chart terminal that is not in cluster.
Click and compare.
These should be two property nodes that do the exact same thing, but they don't. You will notice you cannot access the history data of the chart in the cluster. To clear the chart you need to access the history data and write a null array to it, which works fine if it's not in a cluster. Is this a LabVIEW quirk with clusters or is there a workaround to wipe the data?

> I want to erase the chart history of a chart inside of a cluster.
> This seems apparently impossible to do
> Wire indexed reference from AllObjs[] to left 'reference'
> node of "to more specific class"
> Drage to diagram property node, under app control
> Wire output terminal of "to more specific class" to property node.
> Create property node from Waveform chart terminal that is not in
> cluster.
> Click and compare.
>
> These should be two property nodes that do the exact same thing, but
> they don't. You will notice you cannot access the history data of the
> chart in the cluster... Is this a LabVIEW quirk with clusters or is there a
> workaround to wipe the data?
The problem is that the property nodes aren't of exactly the same type.
To illust
rate this, popup on the chart's implicit property node and
choose Disconnect from Control. Note that the class name at the top
includes (strict) whereas the one created by casting to more specific
doesn't.
If you go to your chart and create a reference directly from it and wire
that reference to the middle terminal of the To More Specific, it will
contain the History data.
Here is why.
Some LV controls/indictors, like the Boolean, are always the same type.
Others like numerics and graphs/charts either adapt to type or allow
for selection of various datatypes. Properties that are common to these
are exposed as a nonstrict class, and if the value's datatype is
included, it is considered strict and is actually a unique class built
on the fly.
Greg McKaskle

Clearing a waveform chart

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