LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

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

How much fluctuation are you getting?  We need to know to determine if this is a set-up issue or if it is a noise thing.

"Should be" isn't "Is" -Jay
0 Kudos
Message 11 of 28
(652 Views)
When I run the VI the voltage starts at about .1 and it slowly goes up to around .34 and it stays between .34 and .36. This happens even when I change the voltage on the power supply, or even turn the power supply off.
0 Kudos
Message 12 of 28
(637 Views)

stizzle wrote:
When I run the VI the voltage starts at about .1 and it slowly goes up to around .34 and it stays between .34 and .36. This happens even when I change the voltage on the power supply, or even turn the power supply off.

OK,

you have a set-up issue.

 

Double check your connections.  Remember the "first rule" of a technician is to never  assume anything!  Your connections or your DAQ channel are bad.   Check them by changing channels and changing the connections


"Should be" isn't "Is" -Jay
0 Kudos
Message 13 of 28
(631 Views)
Ok I changed all the connections and tried all the channels and I get the same results.
0 Kudos
Message 14 of 28
(605 Views)
What does a voltmeter show?
0 Kudos
Message 15 of 28
(603 Views)

Do you want the voltage across one reference and the wiper? It might take me a bit to get ahold of a voltmeter, but in the mean time here is the VI i am using.

Thanks for all the help!

0 Kudos
Message 16 of 28
(595 Views)

Yes.

 

Any time you suspect there is a problem with the signal going into your DAQ, it is a good idea to verify what that signal is with an independent source.  Do it while it is not connected to the DAQ, and do it again when it is.

 

A good multimeter is a vital tool for anyone working with anything electrical.  You can find decent ones at Home Depot that are inexpensive.  Get a hold of one.

0 Kudos
Message 17 of 28
(578 Views)

Ok so I tested the signal from the potentiometer and it is working correctly. When I tested it while it was not connect the DAQ the voltage read 5v and it moved down to 0 as I extended the linear actuator.

However when I connected the potentiometer to the DAQ the multimeter did not read anything. So I tried moving the reference from the ground on the DAQ to the ground on the power supply and the signal from the pin with the wiper started reading correctly from 5v to 0 as I extended the actuator. 

 

I then tried to set up the DAQ assistant subVI using this new configuration. I tried all three terminal configuration options, differential, RSE, and NRSE and I got the same results I was getting before. 

 

This leads me to believe that there is a problem with the way I am configuring the DAQ assistant subVI.

0 Kudos
Message 18 of 28
(551 Views)

No, you don't have a problem with the DAQ assistant.  That is software.  Since you see different voltages with the multimeter depending on whether you have the DAQ card connected or not shows that you have a hardware/wiring problem.

 

Quite a few messages ago, you had some descriptions about how you have things wired up, but I'm still not clear on what you were saying.  Draw a diagram showing how your potentiometer, voltage source and DAQ card are wired up (including pin numbers) and post that image here.

0 Kudos
Message 19 of 28
(545 Views)
Here is a diagram of the setup.
0 Kudos
Message 20 of 28
(533 Views)