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Measuring Current & Streaming 5 channels


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#1 jstigwood

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Posted 08 November 2013 - 04:43 AM

Using the U12 and Labview - can you use this to measure current?

 

I have a labview program measuring voltage ok from each channel - but how would I go about Current?

 

Also - is the max number of streams 4? if I was to measure 5 channels manually using labview (+5v usb voltage) would this overload the Labjack.

 

Thanks in advance,

 

James



#2 LabJack Support

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Posted 08 November 2013 - 11:45 AM

You need a current sensor that converts the current to a voltage signal.  Typical options are a shunt resistor, hall effect sensor, or current transformer.  Tell us more about your current ... amp range, voltage level, ac or dc, and can you measure current at the low side of your load near ground, or do you have to do a high-side measurement.

 

http://labjack.com/s...s-guide/2.6.3.7

 

Stream mode only supports up to 4 channels on the U12:

 

http://labjack.com/u12/datarates

 

Consider moving to any of our other devices (check out the U3, U6, and T7) to stream lots of channels at much higher data rates:

 

http://labjack.com/u3

http://labjack.com/u6

http://labjack.com/t7



#3 jstigwood

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Posted 10 November 2013 - 01:42 PM

This will be used for measuring USB Volatge - (~4.5V to 5.2V)

 

and the current draw should be 0 to 300mA.

 

Some component values would be great for determine this current draw.

 

Many thanks

 

(Streaming - I am going to use a U3 probably... or just use 4)

 

does using a U3LV for current give me more scope?

 

James



#4 LabJack Support

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Posted 11 November 2013 - 02:48 PM

You could use a shunt resistor, but you would have to think about where to put it, grounding issues, and burden-voltage/amplification.  Lets consider a hall-effect first.  This one looks good to me:

 

http://www.digikey.c...3253-ND/1956382




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