PotentiometerGetNormalized.vi

Technical NI LabVIEW
#1

I’m totally baffled by this VI. The help system for this VI reads exactly the same as AnalogChannelGetAverageVoltage.vi. Yet the little bit of the readings I’ve seen from this VI look like they range from 0-1. It almost sounds like some sort of percentage of the total voltage range.
FYI, the range of values I’ve seen from this VI runs between .040 to .365 using roughly a third of the total turns of the potentiometer. These values don’t sound like voltages to me. I haven’t been able to test this extensively because the mechanical guys are still tinkering and I can’t get much time with the robot.

Does anyone know the range of values this VI should output? I really need to know before I can trust our arm to PID control using this VI.

#2

That makes sense. 0.365 minus 0.040 equals 0.325, which is pretty close to one third.

Does anyone know the range of values this VI should output?

I’m not a LabVIEW guru but it seems awfully likely that the output range is 0 to +1, representing the fraction of the total output range of the pot.

#3

It looks like the help for that VI is incorrect. If you look at the diagram, you’ll see that it divides by the instantaneous voltage of the rail to correct for sags, and it returns a value between 0 and 1.

Greg McKaskle

#4

Duh! I didn’t even think to open the diagram. I now see the output is constrained to a range of 0 to 1. Sigh, it’s been a long build season.

Thanks again Greg.

#5