ADXL377Z Accelerometer with NI9269 and NI9205

[BardiyaAk]

Dear All,

I have four accelerometers, ADXL377Z, which I want to excite them with 3V by NI9269 and read the output voltage with NI9205.

I wrote the code in labview, but I believe that I'm not reading it correctly, since I have a lot of noise in the output. Would you please help me with that? I need to acquire the data with at least 1kHz rate, that is the reason I put the timed-loop period 1kHz.

Accelerometer Specsheet: http://www.analog.com/media/en/technical-documentation/user-guides/UG-427.pdf

Thank you all! 

Bardiya

[Henrik_Volkers]

Have you read the DATASHEET of the sensor  ??

What is the specified noise?

What value have the filter capacitors ? OK assume no change...   so 10nF->500Hz   ...   Which bandwidth do you need for your measurement? Increasing the caps (lower the bandwidth) will reduce the noise.  

can't look at your vi  .. still stuck with an older version...

[BardiyaAk]

"C1 (100 nF) at VS is a bypass capacitor to reduce supply noise. C2, C3, and C4 at XOUT, YOUT, and ZOUT, respectively, are filter capacitors (10 nF) to set the bandwidth to 500 Hz."

So, when I want to use the filter, I need to put the cut-off frequency as 500Hz? What do you mean what bandwidth do I need for my measurement? I'm a beginner in sensors, so I really appreciate any help also.

Also, am I using the correct timed-loop period for reading the data with 1kHz rate?

I appreciate your help and guidance.

Datasheet of the sensor: http://www.analog.com/media/en/technical-documentation/data-sheets/ADXL377.pdf

[Henrik_Volkers]

I know the way to the datasheet 😉   thanks for link however....

My Question was more in the direction:Have YOU read it?

Same with bandwidth...   What signals do you want to measure? What bandwidth do you need? 

So if you sample with 1kHz (since you sensor as given has this bandwidth) you also can reduce the noise (and bandwidth) by applying a software filter.

In LabVIEW hit Help-Examples-  search filter

[BardiyaAk]

Oh, sorry.

Awesome thanks. However, I still don't understand what do you mean by "what bandwidth am I need". I'm measuring the three signals of  x-, y-, and z-direction accelerations.

Thanks!

Bardiya

[BardiyaAk]

Anyone who could help me with the labView reading rate?

My sensors are reading with 1kHz, what sample rate should I use in the labVIEW (timed-loop) and based on that for filtering them?

Thank you so much all.

Best,

Bardiya

[BardiyaAk]

I understood that for changing the sampling rate to 1kHz, I need to change the scan engine sampling rate from 10ms (default) to 1ms. I changed that, and in the time-loop you need to read as fast as at least 1kHz also.

Best,

Bardiya