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encoder and current measurment


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#1 kit

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Posted 02 May 2013 - 07:21 PM

Using a U3, I have individual set up an encoder and a current controller. Individually running the pvt motor.VI (attached) I do not have any issues reading current but when I put it in the frequency measurement the current is dipping (resetting), I have no idea why. Any help would be appreciated. The encoder is attached to FI06/7 GND, VS The current controller is attached to DAC0/1, FI00/1/4, GND, VS

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#2 LabJack Support

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Posted 03 May 2013 - 01:39 PM

So are reading a voltage signal on some input? And that voltage changes when you do something else? What does it change to? The newest LabVIEW we have is 7.1, so can't open your 8.2 VIs. You can post screenshots if you want us to look at something.

#3 kit

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Posted 06 May 2013 - 04:20 PM

im measureing the current input and output to a dc motor, at the same time im using the 32bit frequency VI to measure the rpm with my encoder. Sepretly they both work fine but when i put them together the current dips. I think i am sending another single to FIO4.

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#4 LabJack Support

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Posted 07 May 2013 - 09:11 AM

Do you have a U3-HV or U3-LV? I don't see any obvious problems in the screenshot of your VI. I see that you are using a call to eAIN to measure the voltage of AIN1 versus GND. What is the correct voltage you should read and what is the bad voltage you are seeing? If you use a DMM to measure from AIN1 to GND, what does it report?

#5 kit

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Posted 07 May 2013 - 06:34 PM

Turns out it was the timer clock divisor, it was set at 24 and it was causing the interference. I have changed it to 2 and i get real rpm and analog signal measurements. Thank you for checking my code I really appreciate it.

#6 LabJack Support

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Posted 08 May 2013 - 11:41 AM

Perhaps the DAC was getting messed up by reducing the clock frequency, and it was the DAC that was actually causing your problems? See the 4th paragraph here:

http://labjack.com/s...users-guide/2.7


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