Accelerometer Reading Hardware

[DL84]

Hi all,

I've got a project involving 3 accelerometer readings simultaneously.  We will be purchasing our hardware through NI, but another engineer I work with seems pretty intent on buying some other hardware also (that I think is unnecessary.)  I'd like your opinion on whether or not LabVIEW can manipulate input I will be collecting with my hardware... to provide the same functionality as his extra hardware plus mine....

Testing: We will run this test, and if vibration is larger than X, test fails.  If test fails we do more signal analysis to troubleshoot.  If doesn't fail, product is good to ship to customer.  Will be coding with LV8.5; and will be purchasing the sound/vibration toolkit.

Hardware: The NI hardware I've picked is for accelerometers specifically (NI USB-9233).  It's got 3 BNC connections you just hook up and read the output from the sensor. The hardware he is requesting we buy also, will pass through the analog signal of the transducer (BNC from accel. --> this hardware --> output is BNC connector)  This will still need to go into a DAQ to get into labview...but the difference is, this hardware also has a 4-20mA output pin thats proportional to the accelerometer vibration output.  So when transducer is at max, output is 20mA off this output.

What I think:  I've not done a signal analysis program yet, (Excited to though 🙂 ) I'm mostly responsible for automation/testing.  The 20mA output is going to require an additional ni 9233 to read each of the channels. (6 I/O...3 for 4-20mA bnc, 3 for analog signal bnc).  It has to be easy enough to do this testing without the 4-20, having only the full output signal to pull apart and analyze.  It seems like such a generic test, that the toolkit should handle it no problem.  What do you think from the software side of things?

[Henrik_Volkers]

Depending on your sensor you might need an additional charge amplifier. What type of sensor do you want to use?

[DL84]

The sensor is a CTC Model AC102-1A.

Datasheet : https://www.ctconline.com/fileup/AC102%20Series.pdf

[Alex A.]

It looks like the sensor you chose outputs the 100mV/g with a max of 50g vibration which would be within the +/- 5V range of the USB-9233.  I don't see a real reason to add the other hardware to output an amperage for the accelerometer.  Taking two sets of measurements (voltage and current) for each sensor would be overkill.

[Brian_Beal]

This type of sensor usually requires a constant current source, and hence some signal conditioning to get a voltage output.  Take a look at this: https://www.ctconline.com/pdf/techHelp/07-Sensor%20Power%20Requirements.pdf

[Alex A.]

The specifications located here on page 12 shows that the NI-9233 provides the 2mA per channel excitation required as noted in the above document about those accelerometers.

Message Edited by AA_meeting on 09-12-2007 12:11 PM

[DL84]

The NI rep mentioned the 9233 would provide all excitation voltage necessary through the BNC connection.

I assume the power for the 9233 to operate is via the USB port, and not an external supply.

[Alex A.]

Correct, the 9233 should provide the excitation necessary by way of the USB.  As a bonus tip, using USB ports on the back of a computer are more reliable for providing excitation because they are directly connected to the motherboard.