how can I fix shift in the graph analog input signal from USB-6251?

[SailinShoes]

Hello,

I'm trying to get rid of the downward shift in my input signal, I'm creating a Sine wave signal, and directly inputting it into the Analog In from Analog Out on the same card, just reading more samples. For some reason there is a shift in the signal that I can't get rid of. The Signal In graph is shifted -0.1V. Do I need to set up some property node to fix this? I'm fairly new to LabVIEW...

I have included a screen shot as well as a sample of my VI. I'm using Labview 7.1 and the NI USB-6251 DAQmx card.

Thanks!

-Mike

[ChrisR.]

There's no downward shift, as you can tell by looking at the positive and negative peaks of the sine wave. The waveform is stopping on the last point of your sine wave, which is not 0, but about -0.1. You could add some phase shift to the sinewave generation, or generate one more sample to get rid of the problem.

[SailinShoes]

OK, that does make sense as to why the peaks are there...

If you look at this next screen shot, it seems that if I could somehow skip reading the first sample IN, I can get all of the info to match. I was able to match the ends by adjusting the frequency a little.

Is it possible to skip a sample?

thanks for the help

-Mike

[SailinShoes]

nevermind....I got it!!!

I put a DAQmx Read Property node on the input and offset it by 1 and BAM.....

Now it matches. I'll show a screen shot again for good measure

Thanks