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Member
uÖzkan
Posts: 67
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Negative polarity problem

I'm using in my dynamic force project the USB-6210,  'PCB 201B04 pozitive compression force sensor' and PCB 480B21 sinal conditioner.

Altough i restricted the 6210 input range to 0-5 V but i saw negative value as attached file.

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GarPar
Posts: 241
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Re: Negative polarity problem

Hi uOzkan-

 

     The chart you posted has values listed in Newtons.  What is the output range of your sensor?  Does it output 0-5V?  What does this signal conditioner do?  Your 6210 may still be seeing 0-5V, but 0.01V may correspond to a negative value in Newtons (?).  You may try placing an oscilloscope on your sensor/signal conditioner to see what voltage it is actually outputting.

 

     I hope this helps.  Best of luck with your application!

Gary P.
Applications Engineer
National Instruments
Visit ni.com/gettingstarted for step-by-step help in setting up your system.
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Seth_B.
Posts: 756
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Re: Negative polarity problem

It should also be noted that there isn't a 0V-5V input range on the USB-6210, only ±5V.  As a result, even if you set the input range to 0V-5V, the actual range is ±5V and thus negative values can be returned if they are measured by the device.

Seth B.
Staff Test Engineer | National Instruments
Certified LabVIEW Developer
Certified TestStand Developer

“Engineers like to solve problems. If there are no problems handily available, they will create their own problems.”- Scott Adams
Knight of NI
Dennis_Knutson
Posts: 33,880

Re: Negative polarity problem

And of course setting the range to 0-5 with the DAQmx configure channel does nothing to change the actual range of the card which is +/-5V.

Member
uÖzkan
Posts: 67
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Re: Negative polarity problem

OK.

Altough i have changed the input voltage rate to nominal, no any difference.

Could you analyse my vi. Because of i have checked all of my hardware. 

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GarPar
Posts: 241
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Re: Negative polarity problem

Hi uOzkan-

 

     Just looking at your VI doesn't seem to raise any red flags.  You are doing a lot of manipulation to your data, however.  It could be that you are multiplying things wrong, or indexing your arrays incorrectly.  Is you data negative if you just look at it raw?  Meaning, before you perform any arithmetic, what are the values - are they negative?  You say you have analyzed your hardware - have you verified that the signal coming into your hardware is positive?

 

     I hope this helps.  Happy New Year!

Gary P.
Applications Engineer
National Instruments
Visit ni.com/gettingstarted for step-by-step help in setting up your system.
Member
uÖzkan
Posts: 67
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Re: Negative polarity problem

Dear GarPar,

 

This is most probably ground problem because of some noise pick signal up of pigtail connection. 

 

Active Participant
GarPar
Posts: 241
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Re: Negative polarity problem

uOzkan-

 

     That could very well be the case.  Try changing wires/connectors to see if this fixes the issue.  As I said before, your code seems fine at first glance.

Gary P.
Applications Engineer
National Instruments
Visit ni.com/gettingstarted for step-by-step help in setting up your system.