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measure angular position


i'm trying to acquire the angular position from an third party encoder which have 500 pulses per revolution, with a USB 6259.

i've take the example "measure angular position" and i've added a proportional factor 43:1 due to a gearhead.


the position acquired is correct but not the pulses readed.

I've notice that the description of the examples warns that "Position measurement only works with TIO counters"


it means that with third party encoders may occur errors?

Message 1 of 4

Hello Chatter,


What mean that the position acquired is correct but not the pulses readed?


Position and pulse are stricly connected and I think that it is really strange that you can read an information missmatch. Have you create a VI? Can you post it?



Simone S.
Academic Field Engineer - Med Region
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Message 2 of 4

hi simone

i've found in a shift register the source of my missmatch..the VI now works fine

thank you

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Message 3 of 4

Hi all,


I am trying to use quaduature encoder with my NI DAQ 6259 USB to measure the position of the shaft at a particular instance of time.

Let me describe the application for which I am using the encoder.
I have a 60 degree constant torque motor whose shaft is connected to a long tube which is inturn connected an  airfoilshaped piece. The motor is given a sinosoidal wave with a given frequncy and amplitude so it caused the piece to fluctuate on both sides. But to make sure that the piece fluctuates equally on both side I am using encoder so that it gives me the exact position of the piece.
As of now I am using the angular position vi to given the angular location of the shaft as it oscillates. But since this VI takes the internal sample clock , the sampling rate is high and its giving me position for even slight moment of shaft. But I do not want the intermediate positions of the shaft , I am only interested in the two extreme positions of the shaft. I am not sure how to do that


I know there is the way of generating the sample clock internally with frequency and duty cycle specified so that i can take the counter meaurements only at particular instant of time.

I was thinking is it possible to use the sine wave as a source of clock and trigger the counter so that it will angular measurements only which it has maximum and minimum amplitude so that it will give me exterme positions of the shaft.


Manjul Gupta


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Message 4 of 4