I have trouble reading a voltage across a FP-AI-102.

[HYPER]

I have read a constant voltage across a voltmeter, yet when I plug into the FP-AI-102, the voltage jumps around. I have also tried changing the source of the voltage to a DC power supply, in which case the LabView software reads the voltage perfectly. I believ it is a problem in my programming. If you have any suggestions on a possible way to program the LabView to read the voltage, please let me know.

[preston_johnson]

It sounds like your voltage is an AC voltage. Your voltmeter typically will employ an integrating ADC which essentially averages its readings to get a steady reading. If your signal is changing, similar to a sinus signal, you will see a changing voltage at the fieldpoint analog input level. Since the ai102 can scan its inputs at about 200hz or more (2.8ms), you get lots of voltages to work with. You can test this theory by putting your voltage on an oscilloscope.

So, in LabVIEW scan the voltages as fast as you can, and then either average, or better yet use a statistical median. I like the median as it is not affected by outliers.

I hope this helps.

Sincerely,

Preston Johnson

[HYPER]

Could you please give a more detailed explination of how to average, or better yet how to obtain a statistical median, and moreover how to use it.

Thank You