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

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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!
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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 to pass waveform chart in a loop in a sub vi to calling vi

It has been awhile since I made my last application. It has escaped me how to run a VI with a loop in it as a sub VI and still pass the waveform chart up to the calling VI. I am trying to use the Bridge Continuous example as a sub VI and pass that waveform chart up to the calling VI that selects which load cells to monitor. But when i run the calling VI it stops at the sub VI with a green arrow.

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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How to set waveform chart to start data since beginning of run

Solved!
Go to Solution.
Attachments:
TCs.vi ‏106 KB

You need to check the update mode of your chart.
Strip Chart—Shows running data continuously scrolling from left to right across the chart with old data on the left and new data on the right. A strip chart is similar to a paper tape strip chart recorder. Strip Chart is the default update mode.
Scope Chart—Shows one item of data, such as a pulse or wave, scrolling partway across the chart from left to right. For each new value, the chart plots the value to the right of the last value. When the plot reaches the right border of the plotting area, LabVIEW erases the plot and begins plotting again from the left border. The retracing display of a scope chart is similar to an oscilloscope.
Sweep Chart—Works similarly to a scope chart except it shows the old data on the right and the new data on the left separated by a vertical line. LabVIEW does not erase the plot in a sweep chart when the plot reaches the right border of the plotting area. A sweep chart is similar to an EKG display.
From the help menu:
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.
Attachments:
resp2.jpg ‏36 KB

How to take waveform chart data and put it into an array

Hello all,
I am new to programming in Labview, and am learning basically by watching youtube video and such. My question is how to take a set of random data that I have written code for and linked to a waveform chart, and put the data into an array so I can calculate the mean of the data set. If there is an easier way to calculate the mean of the data set I am all ears, but I need to be able to display the mean on the front panel each time the code is run. I have attached a file of my code.
Thanks
Attachments:
CA1.vi ‏11 KB

Welcome.
If you have not done so, look at the on-line tutorials on Getting Started with LabVIEW on the NI web site.
A chart has a property known as History which retains some previous values. You can get access to the the History property by popping up on the block diagram terminal of the chart and selecting Create >> Property Node. Note that the history length can be set via a pop up menu. The default length is 1024.
Other comments: When you know the number of iteration in advance you should use a for loop rather than the while loop.
You can also use an autoindexing tunnel at the boundary of the loop to create an array. It only contains the values from the current run, unlike the chart history which can retain values between runs (as long as the VI remains in memory). Watch the two Mean indicators as you run this VI several times.
The error wire is to assure that the history property node runs after the loop. Disconnect the wire and watch the Mean and Mean 2 indicators carefully.
The Wait is to slow things down a bit so that you can see what is happening.
Lynn
Attachments:
CA1.2.vi ‏11 KB

How to log waveform chart data in any file at specific interval

i am using labview 7.0. i want to save waveform chart data in the file at specific interval given by user. Please give me solution for that.
falgandha

Open the example finder (Help>>Find Examples) and look at the Write Datalog File example. You can also convert your data to text to save a simple text file. Also, the tutorials in the following links probably cover something similar.
To learn more about LabVIEW, I suggest you try searching this site and google for LabVIEW tutorials. Here, here, here, here and here are a few you can start with and here are some tutorial videos. You can also contact your local NI office and join one of their courses.
In addition, I suggest you read the LabVIEW style guide and the LabVIEW user manual (Help>>Search the LabVIEW Bookshelf).
Try to take over the world!

How Does the Waveform Chart Allocate Memory in LabVIEW?

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?

> 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?
This depends a bit on the datatype. For all charts except those with
the waveform datatype wired up, all memory is preallocated when the VI
loads or compiles. Some datatypes, like the 2D array can add plots at
runtime, and obviously the chart history will need to reallocate when
that occurs.
If the chart has a waveform or array of waveforms wired to it. It has no
way of knowing how many points are in a waveform and will need to
allocate them as they arrive. It has a top array of waveforms that is
preallocated.
I answered your question a
bout the chart, but I'm not sure if this is
what is causing your problem. If you are setting the chart history to a
very large number, you might try smaller numbers and see if that is part
of the problem. Otherwise it might be some other part of your diagram.
Greg McKaskle

How to use waveform chart for slow data

For slow data acquisition (e.g. 1 sample / sec) in the case of using DMM, how to display those data in a chart / graph?
For this sampling rate, there will be only 1 point in the chart.
How to buffer them and display them in a sequence?
Or, any other method?
thanks

Here is a quick example showing chart, graph and XY graph. All YOU need to do is use a chart and wire your DMM reading right to it. Charts have their own built in history (you can change the buffer size by right-clicking > Chart History Length)
For more info see the Examples... Building User Interfaces > Displaying Data > Graphs and Charts
Using LabVIEW: 7.1.1, 8.5.1 & 2013
Attachments:
MultiGraphs.vi ‏17 KB

I use waveform chart VI to plot the setpoint as a g

reen line, process variable value in a white line, maximum and minimum in red lines.Is there a way that I can change the process variable color only for those points when the values are out of max and min range and leave the in range points still in white?The reason for doing this is to alarm the conditions when the process variable is out of limits. But we prefer not to change the color for the points when they are in limits.

reen line, process variable value in a white line, maximum and minimum in red lines.Is there a way that I can change the process variable color only for those points when the values are out of max and min range and leave the in range points still in white?Alberto,
Thank you for your VI. It triggered my mind. Now I can use three different plots to represent three different zones, then the color will change.
Great idea! It will work. since I have to use auto scale y, then I changed your VI, now you can auto scale y without seeing the NaN points. see attached VI.
I have the following questions:
1. how to clear XY chart using a front panel button?, seems no attribute for this.
Attachments:
colored_chart1.vi ‏41 KB

How do you clear the chart in an AI Waveform Scan VI upon program start?

I am using a waveform scan vi in a program. The output of the vi is set to "Waveform". What I want to do is have the program automaticly clear the waveform chart each time the program starts. Currently I must start the program, right click on the chart and select clear. I have attempted to use the chart history property node, which I assumed is the correct path to take but so far my attempts have been unsuccessful.

Ahhh, waveforms... These got better in LV 7 I hear.
Will this do it?
2006 Ultimate LabVIEW G-eek.
Attachments:
Problem_example.vi ‏41 KB

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)
>

Multiple values in stacked waveform chart...how to?

I am using a single waveform chart which is staked showing 3 Y-axis value on single X-axis platform.....more clearly I have bundled 3 values and connected to single waveform chart......Now, I want to add one more variable to each staked Y-axis....such that my each staked Y-axis have two variable....so that 6 y-axis variable in 3 staked plot(2 in each) having single platform of x-axis in single waveform chart.......
how to do that?

There are 2 vis that do this. Attach is my chart.
Attachments:
Chart_Ini_Elnik-II.vi ‏24 KB
Chart_Time-Init_No-Hist.vi ‏20 KB
chart.png ‏92 KB

How can i print out the waveform chart?

hello everybody,
how can i print out the "waveform chart". can i do it just push the button. ( example; stop button is stop the program etc..)
i checked the NI examples but i can't understand. i'm new to the Labview.
pls help me.
i added the my program
look forward your reply
regards from turkey...
Message Edited by hknmkt on 05-29-2008 04:15 AM
Attachments:
29.05.2008_11.vi ‏37 KB

hi jim,
i tried the program but it's not running. When i run the program, it's print out without run the program
i added the printed file.
look forward your reply
hakan
Attachments:
error8.JPG ‏8 KB

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 do I add a time stamp to the moving "Major Grid Lines" of a Waveform Chart?

Hello
I am using LV 8.5.1
I am using a Waveform Chart and I have turned on the "Major Grid LInes" using the properties tab of my waveform chart. (properties-->scale->grid lines)
When the code executes, I want to attach a time stamp to each moving yellow grid line.
So as the grid lines move from right to left, there is an associated time stamp for each.
Can someone help!
thanks
J
Solved!
Go to Solution.
Attachments:
how do I add time to the yellow grid lines.vi ‏16 KB

hova2010,
If you right click on your graph and go to X Scale >> Style >> and then choose one of the 3 styles on the far left you shoul see timestamps for those grid lines.
Ben Sisney
FlexRIO V&V Engineer
National Instruments

How to clear waveform chart

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