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periodic interrups disrupting waveform
Solved!
jimmyinct3
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03-24-2010 06:41 PM - edited 03-24-2010 06:44 PM
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Im having a little bit of a problem with an interrupt in the waveform im reading as an input.This doesn’t appear to be a typical windows based interrupt but I’m guess it caused by a mistake I made.The interrupt occurs every 7 seconds without fail, and lasts about a half second.I can post a screen capture movie if anyone wants to see it and will attach a copy of the code.
This labview program runs a loading machine (motor which runs off controlled force, not the more common position control).There is an analog output of a DAQ card (pci 6014) which determines the force driven by the motor controller.So by inputting a sinusoid into the DAQ, I can then read back a force mirroring the analog input via load cell. So after about 7 reps at 1htz, I get an interrupt in the force being read back from the load cell.It always occurs in the exact same spot of the waveform when it occurs (every 7 reps).The position of the interrupt within the waveform can however, change places in the waveform if i stop and restart the program. Changing the loading frequency will show the interrupt will just occur after twice as many reps.
There is no disruption of the plot of the signal which is controlling the waveform (sent to the D to A of pci 6014).
This is labview: 2009 32bit, patched v3
Message Edited by jimmyinct3 on 03-24-2010 06:44 PM
Solved! Go to Solution.
03-24-2010 07:21 PM
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I just made a movie as I feel it will work better than my description.
should be attached.
couldnt upload this extension so used my website.
its very low resolution, but shows the interrupt which in this case, occurs at the bottom of every 7 waveforms.
Solution
Accepted by topic author jimmyinct3
03-25-2010 08:56 AM
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ok, i was able to figure this one out on my own.only took a few days.it was a simple programming mistake on my part, I didnt have a value initializing properly. so what was happening was that the sampling rate of the ADC for each single data point was different from the sampling rate of the sine generator (also generating single points)2000htz vs. 3000htz.
so the time domain was misrepresented during sampling and eventually it had to cause the type of periodic disruption would occur.
