xy graph cutting data

[glskinner84]

Can someone help me figure out what's wrong with my xy graph? It plots perfectly on an O-scope. See the data that's cut at the bottom? I'm at a loss. My vi is attached.

[Gregory]

I do not see a picture that it seems you are referencing of data cut off at the bottom. Try doing it without the Express VI and you will understand how the graphs work better.

[glskinner84]

[glskinner84]

I just did it without the express vi. I'm getting the same results

[glskinner84]

Here's the vi with a noin-express xy. I just pluged the x and y up to another scope and it has a perfect ellipse.

[glskinner84]

It seems like data coming from 'y' is cutoff...like the signal isn't zeroed...

[mateh]

You've demonstrated that it isn't the XY graph that is cutting the data. The problem lies in the data itself.

What is your signal source, and how is it connected to the AI module?

[glskinner84]

my signal source is a sony STR-DE595 Amplifier (x) and an accelerometer/charge amplifer (y). I'm using a NI9125 non-BNC. I looked at the data in MAX and it looks to be the same. Only my accelerometer looks odd. It seems my voltage coming from the amplifier is good.(x)

Basically my changer amplifier is going to my AI0+-, reading the accelerometer, and my AI+- is my input voltage that excites the accelerometer with coils and magnents.

[glskinner84]

but, like I said, when I plug it in to a O-scope II, it's fine. I'm thinking my wiring is bad...should I be using the com port?

[mateh]

Are you applying any signal conditioning between the accelerometer and the 9215? And if so, are you connecting it to the scope in the exact same way?

How you connect the COM terminal will depend on whether your signal source is differential or single-ended and ground referenced or floating, but you must connect it to something. Take a look at pages 12-14 of the NI 9215 operating instructions for help on this: http://www.ni.com/pdf/manuals/373779f.pdf