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Problems with realtime data Please Help

Hi! 
Umm I aplopgize in advance for not knowing much.   I am extremly new to labview and I am trying to something that I was told was simple.  I am trying to aquire A signal ( a vibration) and intergrate it.  That I can do.  The problem I am seeming to have Is that I need  to intagrate the siganle as fast as it is aquired and spit it bcak out as a voltage, not some fintely small time later which is what I get.  In other words Realtime. Another problem I am having is that I get a buffer overwrite error if the frequency or amplitude of the siganl changes too much.  As for the board and software set up I am using Labview 8 and I think the board is 4461?  Processor is 2 gig and have 504 (512) megabytes ram.  I would like to now if this is even possible with this set up and if so a small pointer as to the right direction to help me get started out would be of incredable help.
 
Thanks in advance
 
Blaze
 
 
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I sugest you start with analog acquisition VI's shipped with LabVIEW.

right now, i do not have access to LabVIEW. so cannot locate and direct you to a particular VI.

but if your got to 'search' in examples and type vibration, a relevant example will show up.

hope this helps

any doubts, do get back 

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Hi Blaze,

How fast do you want your control loop to run?

I know that you mentioned you want it to be real-time, but how often are you planning to integrate and update your voltage?  Also, you mentioned there is a delay associated with this operation, how large of a delay are you seeing?

As far as the buffer overflow error is concerned, this means that your code is not reading samples out fast enough to keep up with your sample rate.  Are you using the DAQ Assistant, an example program, or code that you've written yourself?  What is the exact error code?  The solution to this may be to increase the number of samples you are reading at time.

Have a great day!
Travis W


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Hi,

well to post a reply I need the data to be integrated and spit back out as a voltage with no time delay whatsoever. A question is this even possible?  My professor states that when he bought the software and hardware they (National Instruments) said is was.

After going through some of the manuals ( I had this project dumped in my lap )  I found one titled "Real-Time Module User Manual".  It appears not to be installed yet, and it looks to be what I am wanting,  I just wanted to verify the fact that it is what I want and is not a module just to gather data from another computer which is what I am starting to think it is.  In addition the manual it states something about a 7041 board and was I curious if it is needed for the realtime data. 

Again I apologize for lack of experience,  but this seemed to be a nice place to go for some help as is no one I know seems to know much about labview.

Thanks for your help

Blaze

 

 

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Blaze19 Hello!
 
The LabVIEW RealTime Module gives users the ability to run determinstic code on a dedicate Operating System. This means that they can perform data acquisition in Real-Time, which does not always mean fast.
 
In your post, you stated "I need the data to be integrated and spit back out as a voltage with no time delay whatsoever." What do you want to do after you get the voltage values? Do you want to save to a file, display the values on a graph, etc?
 
A typical example of a LabVIEW RT application is one where you have a deterministic (time critical) loop where you do your data acquisition and a non time critical loop where you do your analysis (in this case, it will be your integration).  There is no way to have deterministic applications run on a Windows OS.
 
The PCI 7041 gives you the ability to do data acquisition in Real Time, but it does not have the features of the DSA board (4461) that you currently possess.
 
One option will be to go the PXI route. It is one of our hardware platforms that will run LabVIEW RealTime. You can get a PXI 4461 board and configure the PXI system as a Real Time target. This will give you the ability to acquire your data in real time and then transfer that data back to your host PC. Please take a look at this link for our PXI RT offerings.
 
Lastly, answering the questions posed by Travis W. will be helpful as well. Thanks,
 
Efosa O.
NI-AE
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