Graph voltage not matching input

[James.M]

Double check that you're reading the right terminals with your voltmeter. Remove all extra code (the DC shift, etc) and confirm that your raw signal is coming in the way you expect. If it's not, then you have a terminal configuration or wiring issue.

[glskinner84]

Here's my raw data, with no routines. The green sinewave is the channel in question...

[glskinner84]

And I'm pretty positive I'm ok with the wiring...other than the alligator clips I'm using.

[glskinner84]

Here's the graph with a 1.5v (AA) battery. The signal seems good, no?

[glskinner84]

If I divide the values going to the graph by 1.35, this adjusts the voltage to match my benchtop multimeter linearly. hmmm

[glskinner84]

After some reading I've concuded that I'm reading Pk2pk voltage in Labview and RMS voltage on my benchtop. Oh, gosh. I need to do some reading.

[James.M · Accepted solution]

Oops, I drafted up a reply a while ago but forgot to hit send. I was going to say the 1V you were reading might be RMS because that's about where I would expect RMS to be on your sine wave.

Why do you think its Peak to Peak in LabVIEW?

[glskinner84]

It's an AC signal. Shouldn't labview be reading the pk2pk voltage? It makes sense, the labview voltage is about 35% higher than the RMS voltage read from my benchtops.