Re: Analog input weirdness

Hi,
I'm no pro at this, but I've been doing some noise study myself so maybe I
can shed some light.

What range are you set on? I think the default for the demo is range=1. what
voltage range does that correspond to for your card?
I looked up your card on ni.com and it seems like it's 24bits. so a few
hundred over 2^24 is not much fluctuation, even if you were set for +/-10V. 

My NI card is setup in an office room and I still get mV fluctuations all
the time, even when I properly terminate my input.

Naoko 

> comedi version 0.7.68.1                                                  
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>                         
> driver name: ni_pcimio.c                                                 
>                                                                          
>                         
> board name: NI pci-6014                                                  
>                                                                          
>                         
>                                                                          
>                                                                          
>                         
> Is it normal for an analog input to increment, even when no input is
> applied?                                                                 
>                              
> Using the inp.c demo from the comedlib shows the weirdness.              
>                                                                          
>                         
>                                                                          
>                                                                          
>                         
> if i reset it...                                                         
>                                                                          
>                         
> #/usr/local/bin/comedi_calibrate --reset                                 
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>                                                                          
>                                                                          
>                         
> this is what i get.                                                      
>                                                                          
>                         
>                                                                          
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40515                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40554                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40586                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40614                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40644                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40672                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40707                                                                    
>                                                                          
>                         
> demo # ./inp                                                             
>                                                                          
>                         
> 40738                                                                    
>                                                                          
>                         
>         
>                                                                          
>                                                                          
>                
> all of the other functions (analog out, digital io) seem to work.        
>                                                                          
>                         
> is there something i am missing?                                         
>                                                                          
>                         
>                                                                          
>                                                                          
>                         
> thanks.                                                                  
>                                                                          
>                         
> 
> -- 
> "No government has the right to decide on the truth of scientific
> principles" - Richard P. Feynman (May 11, 1918 - February 15, 1988)
> 
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Received on 2004-08-28Z00:32:45