cRio 9215 problem

[lojius]

I'm using cRIO-9002 controller, Analog input NI-9215 and Labview 8.2.

inputing analog voltage signal(from signal generator-sine wave) to analog input 9215 using DMA. found that measured signal are not symmetrical at Y-axis (refer attachment)

Hope somebody could help me to solve this problem

Lojius

Malaysia.

[Jennifer_R]

Hi Lojius,

Are you using the calibration data?  A good reference is the Analog Input - cRIO project in the examples included with LabVIEW. 

Do you see an offset with other sources of data as well, or only the sine wave from the signal generator? 

[lojius]

Hi Jennifer.

Thanks for the reply. I'm using calibration data. Here  i attached picture of my code. Hope you can help me to solve this problem.

Thank you.

[Jennifer_R]

Hi Lojius,

Thanks for the screen shots.  The only part I might change is where the calibration data is read in the FPGA VI.  The first two frames of the sequence structure can be moved outside of the while loop. 

If you haven't already, I would double check the wiring of the 9215.  You can find the NI 9215 Operating Instructions and Specifications here.  You may also want to try a different slot in the chassis or another NI 9215 or controller if one is available. 

What values are you expecting to see?  Have you used a voltmeter to verify the output of the signal generator?  You can also test your system by running the example program called Analog Input - cRIO, located under Help » Find Examples » Toolkits and Modules » FPGA » CompactRIO » Basic IO. 

Hopefully this will help determine the cause of the offset. 

[lojius]

Hi,

This is the result of measurement using Basic IO example on LV 8.2. As you can see from the attachment, the offset is still there. I already tried using the other NI-9215 module but result still produce the same result. I attached wiring diagram for reference.

Hope to hear from you again.

[Jennifer_R]

Hi Lojius,

The wiring diagram you posted seems to match the manual.  Have you tested with a different power supply or signal generator?  Have you tried using a different slot in the cRIO chassis? 

Also, which version of NI-RIO are you using?  You can check in Measurement & Automation Explorer under My System » Software » NI-RIO.