Reseting vi to get rid of large DC peak

[rwbrook@integratedps.com]

I have a vibration test system designed around the SCC - ACC01 modules in the SC 2345 front end.  The vi was written in 7.1.  All works fine except after the data has completed the averaging of the fft, there is an option for the user to save the data or retake the data.  The 'retake' option takes the vi back to 'live' mode of the fft.  When this happens, a large DC peak occurs in the fft, which adds to the calculated RMS overall, so I would like to eliminate it.  If I restart the vi, this problem doesn't occur.  I can't seen to locate any way to reset the fft.  Maybe I need to completely stop and restart the DAQmx task?

Thanks in advance.  Also, while we are at it, I would like to calibrate my system.  I send the accels back to the manufacturer for that portion.  I believe all that is called for is a NIST traceable white noise generator ( 0-5000 Hertz) put into the SC-2345 front end.  No?

Regards,

Ron

[rwbrook@integratedps.com]

Forgot to mention, I am already well aware there is nothing down that low I am interested in, so I already have a 5 Hz high pass filter on the data.

[Esteban_B]

Hi Ron,

The SC-2345 does not require calibration as it is only a connector block. Then, regarding the fft reset, it’s better if you stop and then restart the DAQmx task, as this will bring new data only to the memory.

Regards,

[rwbrook@integratedps.com]

Steve,

I know the box is only a box, but there is a PCI 6221 DSP card plugged into the computer and there are six accelerometer modules plugged into the SC2345.  What about those?  I hear about software from NI that will carry out the calibration of the PCI 6221, but I can't find it anywhere.

About stopping and restarting the DAQmx, yes that works.  Is there a way to stop the vi and restart it without user interaction?

Ron