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Acquiring three signals using DAQ ?

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Acquiring three signals using DAQ ?

I have created simple program of acquiring three signals using USB-6002 DAQ. The three channels consists of one tacho pulse signal, one vibration signal in X, one vibration signal in Z.

The problem I am facing is that the waveforms of x and z are coming exactly same. They are not same, because when I take individual X and Z signals they are totally different. Please if someone can help me on this topic that would be great.labview code.jpg

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Message 1 of 6
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Re: Acquiring three signals using DAQ ?

Hi maddy,

 

so YOU have programmed something which you don't want to show us as all relevant information is hidden behind some ExpressVIs in your image. We cannot debug images!

And YOU have wired something to your USB6002 which you don't want to show us so we could verify this wiring.

But YOU are expecting us to tell you how to solve YOUR problem…

 

Attach your VI. (Don't forget to apply AutoCleanup before doing so!)

Explain your hardware wiring, a schematics would be nice…

Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2017 on Win7+cRIO
Kudos are welcome Smiley Wink

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Message 2 of 6
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Re: Acquiring three signals using DAQ ?

Hi GerdW,

Thank you for your reply.

Let me explain what I am trying to do. I want to develop a vibration monitoring system which measures vibrations of a rotor in two directions,lets say X and Z. Thus giving me two vibration signals. The third signal is a pulse signal which is generated once per revolution of the rotor.The three signals are connected to AI pins of DAQ.

I want to acquire these three signals simultaneously to understand at what angle of the rotor the vibration amplitude from two sensors were maximum.

The problem that I am facing is that the X and Z vibration are coming exactly identical when rotor is running. In reality, Z direction vibration is more than X direction.

The schematic of the sensor board I cannot share because it is Intellectual property of the company. 

I have attached my VI with this post.

 

Thank you.

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Message 3 of 6
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Re: Acquiring three signals using DAQ ?

Hi maddy,

 

unfortunately I'm stuck at LV2014 currently, so I cannot open your VI.

 

The schematic of the sensor board I cannot share

It's not the sensor board I'm interested in. All I wanted to check is the wire connection to your USB6002: which signal is connected with which pin?

Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2017 on Win7+cRIO
Kudos are welcome Smiley Wink

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Message 4 of 6
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Re: Acquiring three signals using DAQ ?

1. Are the signals biased to ground (ie the signals are not floating)?

2. What frequency are your vibrations at?  You might be filtering out the important information.


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Message 5 of 6
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Re: Acquiring three signals using DAQ ?

You can take a quick guess as to what I'm going to say about this:

Capture.pngCapture1.PNG

Oh, that really makes no sense does it? a 15kHz sample rate and a 100Hz lowpass filter.  Frankly, the index might need a lowpass at say 1.5x the max Rev/Sec but the vibration data would want a highpass filter to eliminate the the rotor speed component. 

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