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How do I use the DAQ Assistant subVI to display voltage readings from a potentiometer

Im new to Labview and I need some help setting up a VI to read and display voltage from a potentiometer. Im using a DAQcard 6046E and a SCXI-1322 module to connect my instruments.

 

The potentiometer is a 3 wire potentiometer. One reference is connected to a 5 volt DC power source, another reference is connected to ground and the wiper is connected to CH+0. 

 

I am trying to use the DAQ assistant subVI but I do not know how to configure it correctly. When I configure it my voltage readings are completely wrong. How do I configure the DAQ assistant subVI correctly? Or is there a better way to create the VI using other functions?

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Message 1 of 28
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What do you mean by the voltages are "completely wrong"?  What are you expecting and what are you getting?

 

It doesn't sound like you are doing anything wrong.  But it is hard to tell since you haven't attached the VI so anyone can take a look at it.Smiley Wink

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Message 2 of 28
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are you using a single ended or differential measurement?  is the 5V return connected to the DAQ?

"Should be" isn't "Is" -Jay
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Message 3 of 28
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The potentiometer is connected to a linear actuator, so when the actuator is not extended I would expect the potentiometer to read 5v and when it is fully extended i would expect it to read 0v. The voltage data I am getting is constantly fluctuating even when I turn the external power supply off.

 

 I have one reference of the potentiometer grounded, and the other connected to the 5V power supply so I guess that would be a single ended measurment if I understand you correctly. 

 

This is what I am doing to configure the DAQ Assistant subVI:

 

-Analog Input

-voltage

-select the phsyical channel ai0 then click finish

-Change terminal configuration to RSE

-Signal input range -5 to 5

 

 

 

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Message 4 of 28
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stizzle wrote:

The potentiometer is connected to a linear actuator, so when the actuator is not extended I would expect the potentiometer to read 5v and when it is fully extended i would expect it to read 0v. The voltage data I am getting is constantly fluctuating even when I turn the external power supply off.

 

 I have one reference of the potentiometer grounded, and the other connected to the 5V power supply so I guess that would be a single ended measurment if I understand you correctly. 

 

This is what I am doing to configure the DAQ Assistant subVI:

 

-Analog Input

-voltage

-select the phsyical channel ai0 then click finish

-Change terminal configuration to RSE

-Signal input range -5 to 5

 

 

 


So what - if any- is the common point of referance between the DAQ and the Potentiometer?


"Should be" isn't "Is" -Jay
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Message 5 of 28
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The potentiometer reference is grounded on the ground pin on the DAQ card. I'm not sure if that is considered a reference for the DAQ.
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Message 6 of 28
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Hello Stizzle,

 

I'm a little confused as to how your application is set up.  First, you said you were using a DAQcard 6046e.  Did you mean a 6036e?  Also, are you connecting the DAQcard to a SCXI chassis?  I'm not sure where the 1322 terminal block is playing a part.  Lastly, what kind of potentiometer are you using?  It sounds like you have a good understanding of how to set everything up.  I just need to make sure I'm on the same page as you before we begin troubleshooting.

 

Regards,

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Message 7 of 28
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Yeah sorry about that, its a 6036E DAQcard. I am connecting the card to a SCXI 1122 chassis which is connected to an SCXI 1322 terminal. I am connecting the potentiometer wires to the 1322 terminal. It is a three wire potentiometer which is connected to a linear actuator, to give position data of the actuator arm.
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Message 8 of 28
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Is the linear actuator or its controller always actively on when you do these measurements?  Have you tried measuring the potentiometer with the actuator and its controller completely powered down?

 

I ask because I've seen situations where a there is a lot of AC or spiky noise introduced in the environment when the motor controller for the actuator is actively engaged.

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Message 9 of 28
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I have tried it both with the actuator on and off and I am getting the same results.
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Message 10 of 28
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