Signal generation from my measured excitation

[sbomy]

Dear,

I measured vibration data outside using an accelerometer and would like to simulate the same vibration in the lab using a shaker.

The data is every 0.0005 sec into a ASCII file.

Would you please let me know how I can generate signal same as my measured vibration?

Thank you.

Soobum Lee

[John_P1]

Hi Soobum,

I see from a previous post that you have a USB-6009, do you have any other hardware?  Ideally you would want a board with hardware-timed analog output (which the 6009 does not support).

If you do have a board with hardware timing, you would read the data from a file (e.g. using Read From Spreadsheet File.vi) and perform a buffered analog output task.  I would suggest starting with the following example:

Help >> Find Examples... >> Hardware Input and Output >> DAQmx >> Voltage >> Cont Gen Voltage Wfm-Int Clk.vi 

If you are using the 6009, you will have to use software timed analog output.  You could read the data from the file as above, but you will not be able to achieve a very accurate simulation since the timing will be controlled by your OS.

-John 

Message Edited by John P on 11-10-2008 12:57 PM

[sbomy]

Dear John,

I have SCC-68 too. Does it support hardware-timed analog output?

Thank you.

[John_P1]

The SCC-68 is a connector block for a M series or E series DAQ card.  You can find out which DAQ cards you are using in Measurement and Automation Explorer under:  My System >> Devices and Interfaces >> NI-DAQmx Devices

You can access Measurement and Automation Explorer through the Tools menu in LabVIEW or navigating to Start >> All Programs >> National Instruments.

Message Edited by John P on 11-10-2008 01:09 PM

[sbomy]

The board I am using is NI-PCI 6251.

Thank you.

[John_P1]

The 6251 has a 8,191 sample on-board FIFO for analog output and can output at 2.86 MS/s on one channel.  I had suggested the continuous analog output earlier, but you may want to use finite if you just want to output the signal one time. I would suggest the following example:

Hardware Input and Output >> DAQmx >> Analog Generation >> Voltage >> Gen Mult Voltage Updates-Text File Source.vi

This should be what you want to do, the vi includes an option to create a sample file to see how it should be formatted.  Let me know if you have any questions.  Thanks and have a great day!

-John