Waveform Chart Y-T Values

I have a waveform chart plotting Voltage values against time. I have to store both the values into a Spreadsheet file. I am able to store the values on Y axis (vOLTAGE), but not the time values. How cal i do so?

One way is to build a waveform data type with Build Waveform function, add t0 and dt info, and use the Export Waveforms to Spreadsheet function. The dt, (delta time) should be readily available from the sampling rate of your data acquisition. You could also create an array of time values, append this array to your Y array for a 2D array and use the 2D input of Write to Spreadsheet file. There is a function in LabVIEW called WDT Get Waveform Time Array that shows how to create an array of time values.

Similar Messages

Set waveform chart size to value 1000

Is there any possibility to set the size of waveform chart buffer to value >1000 in LabVIEW?
Message Edited by Konigusko on 05-03-2006 09:40 AM

Hello Konigusko,
you've got to right-click on the chart and choose "Chart History Length", then this little Dialog box appears.
Dave
Message Edited by daveTW on 05-03-2006 05:21 PM
Greets, Dave
Attachments:
Image1.png ‏8 KB

How to display value in waveform chart

dear sir
i am using labview 7.0 with dsc module for scada.
now i want to display the difference between two tags value in waveform chart. Also i want to display that difference value on y axis and system date and time on x axis continously. Also if there will change in that tag value then there should be reflection of that value on wavwform chart with system time. Really i am in trouble. please help me.
falgandha mohire

Nadim,
Why would an XY graph be preferable to using a Waveform Chart where the "t0" is the time of the measurement?
I don't get it.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Average value for waveform chart

Hello everyone.
Can i make a time interval, where i can measure average value for a waveform chart ?
for example fom 0:30 to 0:45
I have uploadet my VI
Thanks in advance
Oesen
Best regards
Oesen
Solved!
Go to Solution.
Attachments:
Trykmaaling.vi ‏83 KB

Oesen,
When you are displaying data on a chart, the newest data is appears at the right of the previous data. When the chart history buffer is full (default length = 1024), adding a new point deletes the oldest point. Visually it appears that the data slides to the left as new data is added to the right end.
My question relates to how the user would "tell" the program what data to average. In the image you posted you marked a segment of the data to be averaged. Suppose the user marks point "A" as the beginning of the segment. While the user is deciding where to put mark "B" additional data is acquired and point "A" disappears because it is beyond the history length. What does the program do in such a case? A slight variation is the situation where both "A" and "B" have been marked but some of the data is deleted from the history before the averaging or other processing has begun.
Lynn

How to update the absolute time value in waveform chart for labview 6i?

Hey there,
I'm developing a control system using labview 6i on win 2000 os.I'm receiving the sensor data every minute and i want to display the data on a waveform chart with absolute time scale on x-axes. I'm using the property nodes for the offset, multiplier and maximum values putting them outside the while loop and giving them input using get date/time in seconds function. the problem is that the time doesn't gets updated w/ refernce to the computer time and after a certain period the time shown on x-axes lags by several hours. any advise?

Posting an example ussually help us nail these types of issues fast.
I am therfore forced to guess.
Do you have your code written such that the scale operations occur before the loop?
The next thing I have to suspect (not being able to see your code) is if your dt is correct. If your dt is larger than what the chart is set for, then the time will fall behind.
I have included an image showing how the chart can be used to show multiple sample rate plots such that the t0 of the readings are used to control how the readings are displayed. This example uses waveform data types (I believe they were available back in 6i). It should serve as a guide to do what you want.
I suggest you start by recreating the demo and play with it until you have what
you will need in your app.
The beauty of this method is it lets you use the chart to plot signals acquired at different frequecies and plot them all together.
reply to this answer if you have questions,
Ben
Ben Rayner
Certified LabVIEW Developer
www.DSAutomation.com
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction
Attachments:
Wform_demo.bmp ‏427 KB

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

Get max and min values from waveform chart

Hi all
Ive got a waveform chart and want to display the max and min value for the graph. How do i get the respective values?? Im using LabView 8.2
holla
Attachments:
Untitled 231_LV80.vi ‏23 KB

Thanks Mike

Plot more than one analog value to a waveform chart by reading from Serial Port

I have 4 LDRs and I want to plot their values to a waveform chart by reading them from the serial port. I have looked around and found an example of a VI plotting one value to a waveform chart (attached below) but I am unsure about how to expand this for 4 different waveforms, mostly because I don't particularly understand the way is being read currently. If someone could either point me in the way of a relevant example or explain/show me a solution, or explain howthe current VI I have works, that would be greatly appreciated.
Attachments:
LDRread.vi ‏20 KB

Since I assume each LDR (whatever that is) has its own serial connection, you will need to read from 4 different serial ports. From there, just form an array of all the data and write to the chart.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions

Display Data on waveform chart or XY graph over a long period of time

Display Data on waveform chart or XY graph over a long period of time
Can anyone help?
I am acquiring data from an Ni DAQ card with the following parameters - sample rate = 12800, number of samples = 4096. I want to extract order information so as to track changes in the amplitudes of certain frequency harmonics. So I use the sound and vibration toolkit to extract this information as shown in the attached Vi. I will like to plot the resulting amplitudes against real-time starting at the time the Vi was run. I really want the display to show these changes over long periods (eg. days, months and even years).
Problem.
I have tried to plot the Y component of the resulting magnitude for a given order on a waveform chart. My choice of the waveform chart is because I also want to display alarm limits (using the mask and limit vi) (I can't have these lines displayed on an XY graph plot). I tried adjusting the scale offset using the property node and setting the offset to current time. However, the display on the X-axis can only show a span of 2 minutes as will be seen when you run the attached vi. I want the time display on the x-axis to be over a period of days, months and even years. Is there a way to set the maximum scale on the x-axis to be say a year or so in future.
I really want the display to be like the one in in the second attachment.
Attached is a sample VI created using an Ni USB 9234 DAQ card. Any card will do but I am only getting the signal from one channel for this example
I will appreciate any help that can be given to me.
Thanks
Attachments:
Real-Time Graph Display.vi ‏170 KB
Sampe screen1.doc ‏37 KB

Long term testing can be tricky- and we'l get into that later. Lets start with the basics that you have wrong.
The vi as you have constructed it has only one memory element, the chart history length (default is 1024.)
You can change the number of points the Chart will remember by Right-clicking the chart an select Chart History Length from the menu.
But for a long term test - and one where you want to REMEMBER the first value you need a memeory element that is independant of the application. Your PC WILL loose power or need to be rebooted eventually. Heck it might even need to be replaced! you really need to store your data in a file. Preferablly in a file that is backed-up on a regular basis so you don't lose every point of data if the PC dies. It realy hurts when you have to restart a 2yr test because you've lost the 18months of data you collected.
For an application like this I would seperate my "collection" and "Evaluation" operations.
Have one vi that takes the reading and writes it to a file at a configurable rate You may want 1reading per minute for seveal days then 1 per hour for a few weeks- then maybe only once or twice a week for the next couple of years since you are looking for LONG TERM stability. having too much data to evaluate can take a lot of digging to find the few things that interest you (but always take more that you think you need)
Have another utility that COPIES the files, reads them and displays the data you are interested in that day. The data you want to look at won't change over time HOWEVER, you WILL want to analize it in different ways depending on what the data trends look like. Having seperate routines for collection and display allows you to update the display style and analisys without even stopping the collection vi (much less editing the vi)
Jeff

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

How to show two different plots with current system time and date on waveform chart

I am using one waveform chart to display the more than one value continiously. The data are comming properly but i am not getting my system (pc) time and date on x axis. It is showing default date and time (i.e.01/01/1904 5:30:45). Please give me suggestions to display the real time and date on x axis of waveform chart.

How does your data look like? Do you graph waveform data types, dynamic data, or plain arrays/clustes? In the case of plain arrays, you need to set x0 to the absolute start time of your data, e.g. with a property node.
I you would attach your code (or an image) we could offer more specific advice. There are too many possibilities.
LabVIEW Champion . Do more with less code and in less time .

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?
I have tried absolute time format and changing my waveform chart to sweep chart.
Thanks for any help!
Jlam
Attachments:
PDaq- Modified_07-08-2010.vi ‏61 KB

The problem here is that Waveform Charts and Graphs always assume a constant delta time between data points. If you are absolutely certain the data points are guaranteed to be sampled at consistent intervals, the Waveform Chart or Graph is a good fit for the data.
On the other hand, if data points are sampled at arbitrary time intervals, it will be necessary to use the XY graph, where different timestamps for each data sample determine the t-axis (time, horizontal axis).
The deal here is that your horizontal axis is N, Sample Number, not t, sample time. Your samples start at 0, and increment 1, 2, 3... Therefore, if you are taking 120S/sec, it will appear two minutes - 00:02:00 (HH:MMS) - have elapsed in the first second! One way to convert Sample Number to Time is by mulitplying that scale by the factor 1/120. To add a multiplier (or offset) to your scale, go to the properties of the Chart. Likewise, you can use a property node to programmatically set scaling factors on the scale.
a.lia-user-name-link[href="/t5/user/viewprofilepage/user-id/88938"] {color: black;} a.lia-user-name-link[href="/t5/user/viewprofilepage/user-id/88938"]:after {content: '';} .jrd-sig {height: 80px; overflow: visible;} .jrd-sig-deploy {float:left; opacity:0.2;} .jrd-sig-img {float:right; opacity:0.2;} .jrd-sig-img:hover {opacity:0.8;} .jrd-sig-deploy:hover {opacity:0.8;}

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
CC
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

How to set maximum number of data points displayed on waveform chart?

I have a waveform chart set to x-autoscale, but after about 1000 data points, it begins to scroll again. How can I display all of the data points being collected, say 2000 points?

Right click on the chart and select Chart History Length. Enter the value that you need. The maximum is 2147483647 points.

Waveform Chart Y-T Values

Similar Messages

Maybe you are looking for