Multifunction DAQ

cancel
Showing results for 
Search instead for 
Did you mean: 

ADXL377Z Accelerometer with NI9269 and NI9205

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

 

0 Kudos
Message 1 of 7
(3,092 Views)

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...

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


Message 2 of 7
(3,069 Views)

"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

 

0 Kudos
Message 3 of 7
(3,062 Views)

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

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


0 Kudos
Message 4 of 7
(3,049 Views)

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

0 Kudos
Message 5 of 7
(3,042 Views)

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

0 Kudos
Message 6 of 7
(2,981 Views)

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

0 Kudos
Message 7 of 7
(2,956 Views)