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Creating VI for Torsion Transducer

As part of an independent study I was asked to try and create or modify a VI to monitor a torsion transducer. The signal is a triangle signal, which looks like this /\/\/\/\, and measures from 0 to 60 degrees then the signal goes negative for the next 60 degrees and so forth. Since we need to rotate 360 degree, I am having problems with properly measuring the signal. I do not know how to modify the VI to accommodate for when the signal goes negative. The professor that I am working with is not proficient in LabView either, and has been unable to assist me. Any help will be greatly appreciated?
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Is the problem that you cannot measure negative voltages? What are you
using to measure the voltage? Or is the problem that you cannot display
negative voltages? If so, how are you displaying the signal?


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The problem is when we send the voltage data to excel. As an example the data will go from 0V to +5V (0 to 60 Degrees) then +5V to -5V (60 to 180 Degrees) and again from -5V to +5V (180 to 300 Degrees). My problem is correlating the proper voltage to the angle of deflection. How do I configure LabView so that I know when I am at the second +5V I have rotated 300 Degrees and not 60?
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Now your problem is more clear. What you have is a multivalued function. The output can have the same value for multiple input values. Mathematically it is similar to f(x) = sin(x) where x is the phase in degrees. As long as x remains in one 90 degree range there can be no ambiguity to f(x). But sin(2n(pi)+x) has the same value for any integer n.

The solution is to keep track of the total number of cycles. In LV use a shift register and every time the input goes past a 60 degree mark increment the value in the shift register. This value corresponds to the "n" in the sine fuction above.

Lynn
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