Taking snapshot of continuous waveform in oscillosco​pe
my project was -labview front panel has to take the snapshots of the continuous waveform generated from oscilloscope.My front panel is able to take the main graph (which is not rolling or moving ) in oscilloscope and save it in a file in the form of jpeg file.but my main theme is -front panel has to take snapshots of the continuous waveform and save those it in a file in jpeg form .
northridge wrote:
my project was -labview front panel has to take the snapshots of the continuous waveform generated from oscilloscope.My front panel is able to take the main graph (which is not rolling or moving ) in oscilloscope and save it in a file in the form of jpeg file.but my main theme is -front panel has to take snapshots of the continuous waveform and save those it in a file in jpeg form .
See to the below thread, if I had understood your requirement correctly.
http://forums.ni.com/ni/board/message?board.id=BreakPoint&message.id=1020&view=by_date_ascending&pag...
Else, post some code for us to help you more...
- Partha
LabVIEW - Wires that catch bugs!
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Acquire continuous waveforms from two channels on a scope
Hello,
I want to acquire a continuous waveform on each separate channel on my scope, and to see each waveform on it's own graph.
I tried to do it, you can see the VI that I uploaded...
The problem is whan I run the VI - it works, but each graph refreshs in it's time and it doesn't happen simultaneously.
It's a problem because it creates a situation that I can loose a waveform because while one graph is refreshing the other one is not refreshing.
What can I do?
Attachments:
Tektronix TDS 200 1000 2000 Series Acquire Continuous Waveform 2 Channel.vi 35 KBYou are using serial communication. This sort of communication is very slow. So I doubt you will not get much data in real time. You are probably only getting segments of the realtime curve.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far) -
How can I play a continuous, repeating waveform using SO VI's (that isn't choppy)? I gather that I need to buffer the waveform, and I see examples using AO VI's, but how do you buffer using SO Write? What are Circular Buffers and might I use this technique to solve my problem?
Windows ME
Dell Inspiron 5000e
LabView 6iHi MGS!
MGS writes:
> How can I play a continuous, repeating waveform using SO VI's (that
> isn't choppy)? I gather that I need to buffer the waveform, and I see
> examples using AO VI's, but how do you buffer using SO Write? What
> are Circular Buffers and might I use this technique to solve my
> problem?
>
I've tried to do the same, i.e. synthesize a wave for continuous,
non-choppy output, and have some un-solved problems.
A buffer is sent to SO Write, which is then transfered to the device
driver and the sound output hardware. The problem is how to refill the
buffer that is sent SO Write, before the internal buffers of SO Write
and/or the device driver or hardware empties their buffer, which would
result in silence. We need a warning that the buff
er is almost empty,
so that more samples can be constructed. I've found no way to do that
using LabView 5.1.
However, we now how fast samples are consumed, so they can be produced
at the same rate, or perhaps a little faster. If they are produced
much faster, the memory will fill up, but if the difference is small,
the program can run for quite a while. It was a year ago, or so, that
I did this, so I don't remember the details.
A circular buffer can be used in a multi-thread producer-consumer
program. I've done it in C and C++, from some tutorial I found on
threads, or maybe it was from the OSS (open sound system) for
Linux. It is a buffer with a write position and a read position. The
addresses wraps around, so it works a bit like a conveyor belt. The
writer must check that the buffer is non-full, and the reader that it
is non-empty. I'm not sure how to implement it i LabView, or if it's needed.
Helge Stenstrom
[email protected] -
Taking snapshot of oracle tables to sql server using transactional replication is taking a long time
Hi All,
I am trying to replicate around 200 oracle tables onto sql server using transaction replication and it taking a long time i.e the initial snapshot is taking more than 24 hrs and it still going on.
Is there any way to replicate those these tables faster?
Kindly help me out..
ThanksHi,
According to the description, I know the replication is working fine. But it is very slow.
1. Check the CPU usage on Oracle publisher and SQL Server. This issue may due to slow client processing (Oracle performance) or Network performance issues.
2. Based on SQL Server 2008 Books Online ‘Performance Tuning for Oracle Publishers’ (http://msdn.microsoft.com/en-us/library/ms151179(SQL.100).aspx). You can enable the transaction
job set and follow the instructions based on
http://msdn.microsoft.com/en-us/library/ms147884(v=sql.100).aspx.
2. You can enable replication agent logging to check the replication behavior. You may follow these steps to collect them:
To enable Distribution Agent verbose logging. Please follow these steps:
a. Open SQL Server Agent on the distribution server.
b. Under Jobs folder, find out the Distribution Agent.
c. Right click the job and choose Properties.
d. Select Steps tap, it should be like this:
e. Click Run agent and click Edit button, add following scripts by the end of scripts in the command box:
-Output C:\Temp\OUTPUTFILE.txt -Outputverboselevel 2
f. Exit the dialogs
For more information about the steps, please refer to:
http://support.microsoft.com/kb/312292
Hope the information helps.
Tracy Cai
TechNet Community Support -
Generating continuous waveform while preserving properties
Hello,
Thanks to all the past
posters for being so helpful.
I was unable to answer two questions:
The first concerns the maximum
triggering rate in LabVIEW. My goal is to have two trigger / gate blocks set up
working at approximately 25 Hz and 7800Hz, respectively. Is it reasonable to
expect proper trigger/gating even at the higher rate?
Secondly, how can the frequency
and duty cycle of a simulated square wave be preserved for smaller samples? I'm
trying to simulate a 25Hz square wave with 50% duty cycle at 1MHz sampling
frequency, but in 129 – sample increments. Currently, only the first 129 samples are
displayed, even on both “reset phase, seed and time stamps” and “use continuous
generation” modes. In other words, my goal is to have a waveform that is
displayed in ‘pieces’ or in ‘frames’ of the total waveform without resetting
generation.
Your help is always
appreciated,
BME_guyHello,
One way to implement this would be to simply create 1 period of your desired waveform and hold it in an array. Then, on each iteration of your loop, you simply take out the next 129 points. The only catch would be that you will have to account for the rollover case. Well, I decided to just implement this for fun, so I have attached a VI which will take the next N points from a buffer, as well as an example which illustrates how to use it. The subVI is used like a functional global - basically it has an initialization state where you need to specify the buffer (your array of data) and the start index. Then you can call it with the Get Next N Points state and it will get the next N points from the array - accounting for the rollover when necessary. In fact, you can specify getting a different N on different executions of the Get Next N Points state (which is why this must be wired inside the while loop of the example VI which uses the subVI). If you're not familiar with the functional global concept, it's the idea that you can have an uninitialized shift register hold data across executions of a subVI. Save both attached VIs to the same location on your machine, and run the example to see how it works. You can then use my previously attached code to generate 1 period (40000 points for your case) of your square wave, and use that array instead of the example's. Then make N=129 and you're golden.
I hope this helps! Admittedly the code isn't cleaned up - I literally just wrote this a few minutes ago. But it should do the job!
Best Regards,
JLS
PS - Just to be clear, the "subVI" referred to as a functional global above is named "Circular Read Buffer Functional Global.vi" and the example which shows how to use it is named "Example Using Circular Read Buffer Functional Global.vi".
Best,
JLS
Sixclear
Attachments:
Example Using Circular Read Buffer Functional Global.vi 38 KB
Circular Read Buffer Functional Global.vi 47 KB -
How can I convert a continuous waveform to a discrete waveform in Labview?
Please see the attached picture for reference, since I am not sure if I expressed myself correctly in English. My current waveform looks like the gray waveform, and I would like to convert it to the red waveform. Can anyone tell me how to do this in Labview? Thank you for your help!
Attachments:
picture.doc 254 KBGerdW wrote:
Hi Laura,
next time you should attach real pictures like PNG...
You could use a combination of Quotient&Remainder with Multiply to get your desired "discrete" waveform!
Dividing and multiplying will reduce the data to the nearest multiple of 5, but the red line shows that the data is not discretised in the y domain but instead in the x domain, ie the time domain has been chopped.
To achieve this it seems you need to be selecting every nth data point, which is similar to downsampling your data. You can achieve this with the Align & Resample Express VI
http://zone.ni.com/reference/en-XX/help/371361J-01/lvexpress/align_and_resample/
Thoric (CLA, CLED, CTD and LabVIEW Champion) -
I would like to simulate a sample and hold circuit. I was thinking of using the zero order hold vi (for continuous to discrete conversion) in combination with the AC to DC vi? Am I on the right track, or could anyone suggest a better way to do this? Many thanks in advance!
Hi,
The answer to this question was answered in the forum post below:
http://forums.ni.com/t5/LabVIEW/How-can-I-create-and-sample-and-hold-circuit-in-Labview/m-p/2369050#...
If this question is different then please clarify and let me know.
Regards
Arham H
Applications Engineer
National Instruments -
Discrete signal recognition from continuous waveform
Hi Folks,
I'm hoping some of you can give some general pointers on how to better approach this problem. This is the first application I will be actively performing waveform analysis so forgive the amateurishness.
Anyway I'm acquiring a physiological signal at 50Hz and attempting to recognize 'breaths' from this source. The problem is that the frequency, amplitude, and offset will vary depending on the rate and depth of breath (among other things). Below are the ranges I'm working with (in units of "WC pressure):
Freq: 10mHz-500mHz
Amp: 0.005 to 0.145 "WC
Offset: -0.25 to -1.0"WC
In general, I'm trying to reliably get a measure on each breath's amplitude (and offset, but that's easy) and frequency. I have tried two methods: to isolate each breath and analyze, or to buffer say 10seconds worth of signal and analyze. The problem mostly comes in when I try to use the "Pulse Measurements" and "Amplitude and Levels" vi's as part of the analysis package. The way in which they perform their calculation relies on set crossing thresholds - if the signal jumps in amplitude or quickly changes frequency (not likely) and I'm using the buffer approach, I lose calculation on the buffer. Obviously using a fixed buffer size (can) give different results depending on the frequency of the signal.
It's amazing how we (as humans... right?) can discern the breaths from this signal, how we can easily identify problematic shapes, but to do this programatically, it's a completely different story.
I'm just unsure how to better approach this - should i be trying to fit an ideal curve to every group of samples? Attached is a screenshot of ideal (at two distinct rates) and actual.
Message Edited by 8bitbanger on 07-10-2009 02:19 PM
v2009 devel. w/RT
Attachments:
inWC_actual.PNG 44 KB
inWC_ideal.PNG 43 KBFirst, I would filter out the small quick changes is the waveform (unless they are significant to what you are doing or you consider them to be a breath).
In the past, I have tried to heavily filter respiration down to a sinusoid signal and then take the Hilbert transform to create an analytic signal (f(t) + jH{f(t)}). Take a look at the derivative of the phase of this signal which is equivalent to its instantaneous frequenc.
Take a look at attached. I saved data into the Data In control for you to use as an example. This data is monkey respiration, so it is a little faster than human. Play around with the filters to see what is best for your data. Hopefully, this will be of some help.
Randall Pursley
Attachments:
Resp Rate.vi 269 KB -
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Hi, not sure if anyone has encountered this. I have one large PDF file that is 1.2 gb big. It's a textbook pdf so hence the size. It was functioning well until I started reading it on my macbook air preview and using preview to highlight and to annotate within the PDF itself. I know preview periodically save different versions of it as I edit this large PDF file; however, I notice my disk space shrinking considerably more and more as I continue to highlight and annotate on this file (I know I have well over 50 gb of space before I started doing this highlighting and annotation). My disk space just shrunk to dangerously low levels this morning. I managed to transfer some of my other files to an external drive and manage to get back 25 Gb of space right away. Since then all I have been doing is reading this PDF and highlighting and annotating, and my disk space just shrunk to only 8 gb once again. Please help!
I bought my macbook air late last year brand new and had upgraded it to 512 gb of disk space. I have never had an issue with disk space until I started annotating and highlight this huge PDF file. How can I reclaim my space????!!
Thanks all in advance.
DWow, thanks so much. I managed to reclaim a whopping 20 GBs of space just by doing that!
Just a follow up question, this PDF from which I reclaimed 20 GBs of space is actually a backup copy of the original PDF that I have. The original PDF is of course equally huge in file size, and that is the one I initially started highlighting and annotating on. However, a couple of days ago, somehow preview didn't save my edits correctly and corrupted my file and since then I have not been able to open this corrupted PDF file at all (Preview, adobe pro, skim...none of them can open this file anymore). I tried those commericial PDF repair softwares and none of them could fix it and hence I had to restore and use a backup copy of it.
I suspect that there's another 20-30Gbs of space sucked in via the version feature that is attributed to this corrupted original PDF. However, since I can't open it, I can't use the above method to delete all previous versions of it. Any thoughts in terms of how I can reclaim the spaces occupied by the versions of this corrupted original PDF file? Does deleting this corrupted file automatically delete all the previous versions of it?
Thanks in advance for all your help!
D -
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http://discussions.apple.com/thread.jspa?messageID=9216400�
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Hi
I want to print a XY Graph with more than 600000 data with word format but the graph shouldn't be the snapshot can any body suggest pleaseA couple points:
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Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps -
Continuous waveform generation with PXI7952 & NI6587
Hello Everybody,
I am looking for code exemple in LabView 2009 for continous waveform generation with PXI-7952 & NI 6587.
Thanks for you help.Bonjour,
Pour la carte FPGA PXI-7952R il y'a une application de référence ici : http://zone.ni.com/devzone/cda/epd/p/id/6066
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Hello!
I am using the SDK of the Mightex 1304-U camera and am trying to make some alterations to have the Labview software behave more like the natural one that installs into the computer.
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Code.final.vi 96 KBJust as an update, I have been looking further into how to remove elements from an array, which I suspect is what I need to do. In doing so I have found that I would rather replace all negative values with 0, and so far have what is shown below
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