Save portion of a waveform chart

First of all I acquire 2 voltage signals and save them in a file.
The next thing I have to do is to read that file and show a portion of the waveform in a picture inside the page of a tab control, so each page of the tab control has a picture of a different portion of the waveform y different moments.
For example on the page 1, the portion of the waveform from 0 seconds to 2 seconds. The page 2 from 2 seconds to 4 seconds....
What I don´t know how to do is to save that portion of the waveform in a file so i can read it later as an image and put it on a tab control
Thank you.

Like this:
To get the Invoke node, right-click on the graph and select Create->Invoke Node->Get Image.
Message Edited by smercurio_fc on 04-23-2008 08:25 AM
Attachments:
Example_VI_BD4.png ‏2 KB

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How to save data from a waveform chart to a file?

Hi! I have a question:how to save a real time data from a waveform chart? attachement is a example,how can i do to save the data from 0 second to 25 seconds to a file ?thanks!
Attachments:
example.vi ‏23 KB

You can use a property node to get the chart history as a array. Then you can write that data to the file. The data in the array in you example can also be writen to a file. If you only wnat a portion of the data to be saved, use the Array Subset function to get the part you want.
Lynn

Save a waveform chart

Hello!
I am trying to save a Waveform chart into a file usin the Save waveform to a file.
I have been doing test with ramdom numbers in little programs and I was able to save then in waveforms, but I can not do the same in the program that recieves the serial data.
I have attachet my program.
I well be be gratefull if someone could help me. I am sure is a little thing what is wrong but I can not find it.
Thank you for your help.
Angel
Attachments:
cliente_grava.vi ‏112 KB

And unless you only want only the very last acquisition recorded, you're going to have to change your VI. When the while loop stops, all it passes to the write waveform is the very last 1D array captured. If you want all data saved, put the write inside the while so that with every iteration you append to the same file. Or, turn on indixing where the 1D array exits the while loop. This will create a 2D array of all data acquired. Also, using Write Waveforms to file is probably not the best function unless you are actually creating a waveform datatype with timing info. Write to Spreadsheet will write a 2D array of DBLs or create a waveform datatype inside the while loop

How to save X and Y vaue from a Waveform Chart

Hello Everyone!
I'm implementing an adquisition systems that send data to a waveform Chart through VISA. All run properly, but I would like to save the data adquired to an excel file. I saw examples to how to save it, but only save the Y value.
I would like getting the X and Y values in 2 columns different in the excel file.
¿Is it possible?
¿Can someone tell me how I can do it?
Thanks for your feedbacks!
Solved!
Go to Solution.

I meant uploading the actual VI, not a picture of it. You need to fix your code.
You should not be initializing the serial port in each iteration of the loop. Initialize outside, read in the loop, and close when the loop is done.
Why do you have 2 VISA resource controls? Are you talking to 2 different devices?
The event structure serves no purpose in your code. If you are trying to enable/disable the file writing, use a case structure that's controlled by a simple front panel switch.
You should "remember" the path that the Write to Spreadsheet File uses. Otherwise you will be asked for the filename each and every time you try to save. You can do this using a simple Feedback Node:
Since you are reading the value periodically, just use one of the Get Date/Time functions. You can use the Get Date/Time String to get a formatted string. Then you can format your value as a string, and build your array using those 2 values. Or, you can use the Get Date/Time in Seconds to get a numerical value. Be aware that LabVIEW's starting time is 12:00 a.m., Friday, January 1, 1904, Universal Time [01-01-1904 00:00:00], which is different from Excel.
Attachments:
Example_VI_BD.png ‏1 KB

Screen Save Waveform Chart

I have a Labview DAQ VI with some controls and a couple of waveform charts.
I would like to print just the waveform charts but not the whole panel at
times using a screen dump or print screen to include as pictures in a MS
Word report. Can this be done?

Actually, the whole process is rather simple. Attached is a snippet of code taken from LV's report generation tools. Using a reference to a front panel control, it extracts the appropriate data and writes a BMP file.
The vi is inside a quick demo that show how it can build a BMP of a graph. Run the demo and then check your temp directory. There should be a new file there that with a name like CT********.bmp.
Mike...
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Attachments:
graph_test.zip ‏103 KB

How to save the waveform chart information

I am attaching a VI which recordes the power and wavelength from a ILX lightwave power meter. I had added waveform chart to the program to record the values of quatities with respect to time. Please kindly help me to read the quantities on time with saving the values from initial time to final time. I I use shift registers with a built array in the while loop , will it retains the past values?

I had added waveform chart to the program to record the values of quatities with respect to time.
Wrong. Charts don't display values with respect to time!
Hey Gerd,
I don't quite understand. If I wire a waveforme to a waveform chart it stores an processes data as waveform i.e. t0,dt and [y]. This, to me is in respect ot time.
If you meant, though, that it doesn't do that in his case, I very much agree with you.
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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

Has anyone "zoomed in" on a portion of a waveform graph?

Has anyone ever used two cursors to zoom in on a portion of a waveform graph?
I've seen that newer Oscilloscopes offer features to do this both horizontally and vertically.
See the attached jpg for an example of what I'm trying to do. It is from Google Finance. Notice the area circled in red. The two cursors define the portion of the waveform to be displayed on the main graph. There is also a scrollbar beneath them which allows the user to quickly move the zoomed-in area across the graph- I would love to have that functionality on the LabVIEW graphs.
My first thought is that I can do this using mostly property nodes. Not sure on vertical zooming scrolling the horizontal zoom- I'm thinking maybe this would best be done using scrollbars which are not part of the graph itself.
Any ideas or comments?
Thanks,
Dave
Attachments:
deleteme.jpg ‏38 KB

Cursor position is available in Labview via a property node. You can also set about every chart property with property nodes. I have used this many times. Here is a trick. If you have two cursors, Make separate arrays of the x and y positions. Then use the "Array max&min" to sort them. This will make your program independent of the cursor sequence.
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Cursor legend for waveform chart

Greetings again. Is there a method to turn on the cursor legend in a waveform chart (like in the waveform graphs)? I'd like to allow a user of my application to be able to select a portion of a chart and have the application report the value plotted.
I am acquiring data via the Analog In channels of a PCI-6036e at 1500 Hz to plot in real-time. I tried plotting my data with the waveform graph but it only shows the latest readings and does not scroll the data. I know I could build an array and rotate through it as the data comes in but that seems like a lot more effort just to be able to use the cursor controls to highlight data.
Any ideas? Am I being too brief?
Thanks-
-dennis.

Cursors are only avalaible on graphs, not charts. There was a post on this subject yesterday...
See http://forums.ni.com/ni/board/message?board.id=170&message.id=102968&jump=true
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Chilly Charly (aka CC)
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Write data from waveform chart to excel

Hi,
I am trying to create a button that save de real time values recieved in a waveform chart. I don't know how to save it alls, because I don't know if is needed a buffer to save all or how can I do it.
It wil be faboulous if someone give me ideas!
Thanks so much for your support!
Solved!
Go to Solution.

Hi mlop,
You can go through the attached VI. You will get some idea of how to do it..
Regards,
Nitzz
(Give Kudos to good Answers and Mark it as a Solutoin if your problem is Solved)
Attachments:
Untitled 2.vi ‏9 KB

Waveform chart. Send data to Excel

I am monitoring the output voltage from a electronic circuit using LabView 7.1 and a DAQ card.
I have been able to view the output voltage using a Waveform Chart but i have been unsuccessful sending the data to a file. Only one data point gets saved each time.
I am using the "Write to Spreadsheet File .vi "
Could someone tell me what i am doing wrong?
Please see the program attached below.
Attachments:
Attempt 3.vi ‏26 KB

You can build a 1D array as your loop runs. Where your data exits the while loop, right click on the border and select 'Enable Index'.
If you want to save data continously, you need to move your 'Write to spreadsheet file' vi inside your while loop. As it is, only the last data point will be saved when you stop your loop.
You will also need to connect a control or constant to the file path input so that you do not get a file dialog every time your loop iterates. Further, connect a True constant to the 'append to file?' input so that you do not overwrite data.
Also, you may want to insert a wait period in your loop to allow other processes to run.Message Edited by DavidT on 04-27-2005 09:16 AM

Waveform chart data to file

dear sir,
iam getting eight different plots on waveform chart with system date and time. Now i want to store this eight values with system date and time in excel file as per specified time interval. it shoould be online because i don't want to stop my vi to save that data in file. Is it possible? If yes please help me.
thanking you
falgandha

Falgandha,
this can be done with ActiveX or just saving the data as spreadsheet file and then importing it to Excel.
If you like to know more about Excel and ActiveX, you should take a look into the ActiveX-examples of LabVIEW.
Saving data as spreadsheet file is available as examples as well, but maybe it is sufficient for you to use the "Write To Spreadsheet File.vi" from the file IO palette.
hope this helps,
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Capture Wave Form from Waveform chart

Hello,
I am trying to capture the waveform from the waveform chart save it as an image.
The reason I am not saving the data is that we have a lot of test data and we do not want to plot hundreds of waveform again manually.
Does anyone know how to do it?
Thanks!
Solved!
Go to Solution.

Here's an easy way to save an image of the chart.
You can save only the chart as BMP, EPS, EMF or PICT with another method:
Jim
You're entirely bonkers. But I'll tell you a secret. All the best people are. ~ Alice

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?

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).
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Save portion of a waveform chart

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