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U3-HV analog input configuration


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#1 foil

foil
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  • 1 posts

Posted 31 August 2013 - 07:17 AM

Hi,

 

I have to change our labview code because we switched from the national instruments daq to the labjack u3-hv hardware.

 

Now, I have troubles to get it to work. Attached is the labview code for the national instruments daq device.

AI.png

Now, for the labjack u3-hv hardware: AI0 and AI1 are used.

1. LJUD_OpenLabjackS

2. LJUD-eAIN

to get a differential reading:

ChannelP: 0

ChannelN: 1

range -10 to +10V volts (by default for AIN0-AIN3)

 

and now, how do I configure it to get

Number of samples: 2500

Sample mode: Finite samples

Sample Rate: 100 kHz

Active edge: Rising

 

Thank you for your help.

 



#2 LabJack Support

LabJack Support
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  • 8677 posts

Posted 03 September 2013 - 11:23 AM

The max sample rate of the U3 is 50 kHz.

 

The function eAIN does a command-response read of 1 analog input.  To sample at 50 kHz you need to use stream mode:

 

http://labjack.com/s...6/users-guide/3

 

Learn more about stream mode in the following sections:

 

http://labjack.com/s...users-guide/3.2

http://labjack.com/s...ers-guide/4.3.7

 

Check out "U3 easy Stream Example.vi" to get started.  This example does a continuous stream, but in your case it appears that you only want to stream 2500 samples and then stop.  There is not a U3 example just like that, but check out "U6 easy Stream Burst.vi".

 

What is "active edge: rising"?  Is that a trigger for when to start collecting data?  We don't have a function like that built in to hardware or software, so it is just something you would implement yourself in LabVIEW.  I would start with a copy of "U3 easy Stream Example.vi", and then process the data you get back to find the trigger of interest.




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