Waveform data could contaminate x axis display in waveform chart?
Hello
Please take a look at this vi:
Attachments:
Real-Time Chart.vi 19 KB
Ben wrote:
It looks like you are getting bogus time stamps from the SV.
This thread talks about the chart and waveforms.
Try click the Chart on the front panle to find the ignore...
Ben
As far as I understood this example uses "t0" from the waveform data for x axis. I tried this method and it works. The date and time shows correctly. That's great.
But I actually have another request for the chart display, that is to show data in a certain time period, which should be programmable. For example I could let the chart show the data waveform in 10 seconds this time(I mean in one screen without scrollbar), and the next time I execute it, I change the parameter and show the data waveform in 60 seconds.
I tried to modify the initialization like that:
I thought by changing the maximum value of the scale range, I could realize that. This kind of setting didn't really work. before the breakpoint, the time in x axis became chaos again, and after going into the loop it returns to correct value.
Do you have any ideas how to realize that?
Thanks again!
Best regards
zzha
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Saving waveform to retrieve it back to display on waveform graph
I want to save a waveform that I acquire through my hardware and display it on a sweep chart. Its a time based voltage acquisition. I tried using write to spread sheet or save waveform options in LabVIEW 2009. But when I tried to read it, it only shows me 1 cycle of data(I will be suing a graph here because I want to add cursors to it). I want the exact same whole waveform to be displayed on a graph as I had acquired it. I want to avoid using express vi's since I will be acquiring 10 channels simultaneously so I dont want to slow down the execution speed.
I am attaching the base vi that i made to read and write the waveform to a file(I am using simulate signal in this attached vi just to simulate a square wave and check my logic functionality).
Can anyone help, please!
Thanks in advance.
Attachments:
ro_up_read.vi 17 KB
ro_up_write.vi 53 KBFirst of all, the "Append" should only be True when i does not equal 0.
Secondly, you are only dealing with 1 signal, so have the dynamic data converter output a 1D array of scalers. I then found that I had to transpose the spreadsheet on both sides (read and write).
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
Attachments:
Write and Read Simulated Signal.png 86 KB -
***What is your favorite VI or other software to view large sets of waveform data?
What is your favorite VI or other software to view large sets of
waveform data?
I have to look at waveforms with several sets of y data of 10000 or so
points. Should I put this into Excel? There are no cursors, or zoom
capabilities, and so on in Excel.
Using a graph in LV is very slow when loaded down with this much data.
Frankly a scope is easier for viewing waveforms. A scopelike utility
for Windows?
MathCAD?
Is there any neat shareware out there?
Thanks for your opinion,
MikeThere are a large number of analysis packages on the market that can display very large datasets. The one to choose depends largely on the nature of the data and what you want to do with it after you have loaded it in. Wandering down the software aisle at your local Staples you will find at least two or three.
With datsets the size you are contemplating, a major feature to look for is a zoom function that initially shows the entire waveform but lets you narrow in on the data you want to see.
DIGRESSION ALERT
Actually, this sort of algorithm isn't to hard to code. I wrote a viewer once that allowed you to view datasets of arbitrarily large size (in V3 I think... though it may have been in V4). The code initally presented an overview of the entire dataset
by decimating it down to a size that LV could display rapidly. As the user zoomed in using the cursors (not LV's graph zoom) the code would extract the selected portion of the data, redecimate it if necessary and redraw the display. (Which by the way is all the fancy packages really do anyway.)
The tricky part is selecting a decimation function that retains the overall shape of the data.
ENDOF DIGRESSION
Several years ago I wrote an article for a magazine (Personal Engineering and Instrumentation News) that dealt with graphing packages that could handle a million datapoints at that time (late eighties) there were over a dozen programs--and they were all better than Excel...
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
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How do I turn a Labview measurement file into waveform data
How do I turn a Labview measurement file into waveform data, I have done this recreating the waveform out of an array with build waveform vi, is there another way?
OK I am sorted, sorry for such a stupid question!!!!!
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Waveform data not displaying correctly
Hello,
I am having some trouble displaying some waveform data.
I have a DAQCard-6036E card, and I am bringing in 16 analog signals. The task is set up through MAX, and right now is generic. All I am reading is random noise in an attempt to see if my VI even works. The acquisition mode is set to continuous, with a rate of 1k, and number of samples set to 100.
The problem is that I get very intermittent data on the front panel indicators. Only several of the indicators work, and its choppy at best. What am I doing wrong here? Is it a problem with my acquisition mode?
Thanks,
Alex
Attachments:
DAQ (CompactDAQ).vi 39 KB
DAQ.vi 137 KB
DAQ (Air Data Computer).vi 35 KBHi Alex,
I just tried the your VI with the while loops deleted out of the
subVI's and as far as I could see the indicators in the first two
columns of the front panel were updated as expected. The other
indicators are not wired so they will not update. It might look like
some of the wired indicators are not updating each time if the value
doesn't change - ie the potential on the line is the same as the last
read. You might try putting a known signal on each of your test lines
instead of using noise to test your system to verify that the voltage
is changing each time.
If you are still having trouble, post again. I've attached a copy of the VI I used for test.
Regards,
Micaela N
National Instruments
Attachments:
DAQ.zip 95 KB -
Hi,
I've a problem while saving the waveform to a spreadsheet.
The problem that I'm facing is that I'm not able to save/change the time-axis of the waveform graph into the excel spreadsheet.
The attachments below are what I've programmed on.
1st file that would be asked to save is the results of the waveform.
2nd file, supposing to be the time-axis
3rd file, is the multiplication of results of CH 1 and CH 2.
Would be glad if someone can enlighten me with a solution which is suitable for LabView version 8.2 and Tektronix DPO 72004.
Thanks. ((((:
Attachments:
Modification of 2 CH waveforms (Multiply and Sum).vi 63 KB
Modification of 2 CH waveforms (Multiply and Sum) Front Panel.JPG 220 KB
Modification of 2 CH waveforms (Multiply and Sum) BD.JPG 92 KBI've saved it as text file which could be read if I open it with excel spreadsheet.
My aim is to get the time-axis (x-axis) in the file rather than to get the date and time in the file.
The attachment is the waveform results that I've obtained.
Attachments:
waveform vaule.txt 433 KB -
Waveform chart time axis is not matching the waveform data
So here an interesting conundrum I hope you might be able to help me with...
My VI has waveform data sent to a chart, though the data is not being plotted against the current time. Rather, it is being plotted starting way back in the reference time (way back in 1903). I don't understand why this is happening. When I build the waveform, I use the "Get Date/Time in Seconds" function outside the while loop and feed that into my "Build Waveform" Function as the t0 value. My dt value is 0.05 (20 Hz) and then I feed in my array of data in the Y input. Any ideas why the chart is plotting this data over 100 years ago? Thanks!
AndrewHiii, Ronin
Here is your solution.
By default, waveform charts and graphs display the absolute time at time 0 as 7:00:00 PM, 12/31/1903 on a Windows based system. Property nodes can be used to get the correct absolute time to display on the x-axis of the waveform chart.
First, right click the chart on the front panel and select X Scale >> Formatting. Then set the format to Absolute Time.
Create a property node for the waveform chart by right-clicking on the chart on the block diagram and selecting Create >> Property Node. Expand the property node to display two properties. Select the Format property and the Offset property. The Format property is located under X-Scale >> Format and Precision >> Format, and the Offset property can be found under X-Scale >> Offset and Multiplier >> Offset. Right click on the property node and select Change All to Write.
For the Format property, the context help shows that there are multiple inputs to this property. Wire in a value of 7 to set the format to Time and Date.For the Offset property, first wire the output of the Get Data/Time in Seconds VI to the input of the To Double Precision Float VI. Then wire the output of the To Double Precision Float VI to the Offset property.
In addition, if you know the number of data points plotted to the chart per second, you can set the Multiplier property located under X-Scale >> Offset and Multiplier >> Multiplier. If there are x data points generated per second, wire in a value of 1/x to the Multiplier property. A simple example program "Chart with Timestamp" that demonstrates how to do that is attached.
Thanks,
Nishant
Attachments:
Chart with Timestamp.vi 36 KB -
I wanted to use time series line in my analysis but I couldn't get What kind of data is required for this graph? It shows inappropriate data for continuous time axis. I had total amountmin vertical axis and time(year) in horizontal axis.
Check this if not helpful then follow 2 links at bottom
OBIEE - Time Series Conversion Functions : AGO and TODATE | GerardNico.com (BI, OBIEE, OWB, DataWarehouse)
~ http://cool-bi.com -
How to display a waveform in XY format where X is the time in seconds?
I am aquiring voltage from a power sensor and I am displaying this voltage as a waveform in a waveform chart. Now, I would like to display this waveform such that on X axis I have a range from 0 to 30 seconds (X axis should be displayed in seconds of recording not actual time). On Y axis I would have the value of parameter I am aquiring of course.
Any suggestions/examples?It is a data signal type that has timing info in it.
What I am actually trying to achieve is to display the data in a chart (that has seconds on X axis) only when I turn on a button. When I turn off the button the data should stop being displayed in the chart. Problem is that when I turn on the button again the new data displayed should flow from the point where old data stopped being displayed. In a chart having actual time on X axis this is not possible because the time will be different that the time when the data stopped being displayed so you will have a gap between the old and new trains of data. I want continuity and I was hoping to get this if I take the timing info out...
Do you see a better solution for this?
Thank you. -
Date Range For X-Axis On Range Graph
Hi,
Is it possible to use a date range on the x-axis of a range graph rather than having to use numbers
I'm trying to show the various start and end date of projects on a single range graph and i can convert the start / end dates to number and the graph to displays as expected but some how i need x-axis to show the dates rather than the numbers
This is what I've done so far, any ideas?
http://apex.oracle.com/pls/otn/f?p=37821:5
Thanks AndyHi,
Just wondering if anyone had any ideas about how I could achieve this. The senior managers love the way its look but without dates across the x-axis its not much use to them
Thanks Andy -
Help with Multi point chart plot hile using the waveform data type..
Currently I have two channels being transfered into the AI C-Scan block (by means of a build array) in hopes to display the outputs on a chart as well as an output file. As an outout I am using the waveform data type, as I hear this is the way to go. Problem is that I have the the Waveform chart directly connected to the waveform out put the the AI C-SCAN block but nothing is being displayed on the chart. Although the time is updated on the chart it is listed as the year 1903. I do have data these channels as the there are digital outputs for these channels. Perhaps I should use the AI CONFIG and AI READ clocks rather than this AI C-SCAN. Any ideas...
Christian,
Please see the Real-Time Chart shipping example for LabVIEW. This example describes how to set the base time of the chart so that the time and date are correct.
You may want to autoscale the Y-axis as your data may be out of range of your chart and that is why nothing is seen.
Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask -
How to generate a waveform data table for my data acquisition (GPIB)?
Hi everyone, I'm new to labview. I have a question, how to obtain waveform data(an I/O file so I can plot it in graphic software), rather than just plot a waveform graph which is pretty easy, but I want a waveform data table, how can I do that? Thank you very much!
Message Edited by pack2themoon on 12-12-2008 10:05 PMWell, I would tell you how to get the data to display on a table however then you will come to another issue.
The issue is that once the data is in a table, you cannot select all the data at once.
You can only select one cell at a time, I'm not sure why, guess it was an oversight of some kind.
There are a few work arounds, and if you are still interested in this aprroach, I will share them with you.
Cory K -
Is it possible to display a waveform with fixed length and fixed starting point?
Hi,
I am using DAQ assitant to acquire voltage and current measurment of my device. The voltage is a pure sine wave and current is a periodic waveform with phase difference and distortion. I use waveform chart to display the waveform of voltage and current waveform in seperate charts and they work fine.But the waveforms look like moving to the right all the time, in another way ,the phase is always shifting. Now i want to display the waveforms of both with fixed length (say 2 cycle) and also in a same chart. Apart from that, i also want to display the voltage waveform starting form 0 degree (a fixed point )rather than moving all the time. In this case, i can observe the angle difference between voltage and current. Is there any method to achieve this purpose?
Many Thanks,
HaoHao,
first of all, you are using a chart which has three options for updates if the chart is "full":
Strip chart (default)
Scope chart
Sweep chart
These are called "update mode". Test the modes yourself.
Also you have to know that you will not likely have an integer number of periods of your signal in the display of the chart. Therefore, a continuous signal will "move" the graph from update to update.
You can implement some algorithm to discard data to maintain a static "trigger" level for display, but as stated, it will leave gaps in the signal. These gaps are not a concern unless you use the displayed signal for analysis (e.g. FFT).
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it. -
Can I obtain the date of the exe and display it on the fropnt panel?
Hello,
Is there a way that a Labview program can display the date of the exe and display it on the front panel? I am aware of the version info on the application builder, but I did not see a way to get the date when the exe was created.
Regards,
KasparHi
You could use File/Directory Info function in your code like this
cheers
David
Message Edited by David Crawford on 02-24-2010 11:11 PM
Message Edited by David Crawford on 02-24-2010 11:12 PM
Attachments:
App Last Mod.png 17 KB -
URGENT!!WAD AXIS Display Error in EP!!
Hi Guys!!
We r using WAD in our project.I dont know When I am executing it in Enterprise Portal,I am not able to see the X & Y axis displays..
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Thanx in advance
Raj.Hi Raj,
You can upload your role again and then check your WAD in EP.
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