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Unread 03-05-2008, 00:41
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Re: The 2009 Control System Q&A Thread

I hate to follow up my own post, but after some further research, I noticed a slight miscalculation on my part. Looking at this IFI FAQ, the victor speed controllers are obviously going full range at 1-2ms, more or less. The IFI RC is changing the PWM width in 5 us steps, so it's varying the pulse width by 1.275 ms, and we're not using .275 of that range. So the output on the IFI RC has an full range resolution of 200 counts, compared to the cRIO's resolution of 143 counts. So the resolution will probably end up with about 75% the resolution, not the 50% I stated earlier. My curiousity about calibrating the victors to wider pulse widths remains, however.
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Last edited by Kevin Sevcik : 03-05-2008 at 12:19.
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Unread 03-05-2008, 04:36
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Re: The 2009 Control System Q&A Thread

For reference, when the 883 and 884 were profiled they were found to have a step resolution of 6.44us (with some steps actually 12.85us) with the ability to generate 127 discrete voltages.

But as no announcement has been made with regards to motor controllers and their operational specifications, any further discussion is pure speculation.

One closing note with regards to PWM generation - the cRIO is not limited to 256 steps, thus allowing for far longer PWM periods while still maintaining the 6.625us resolution.
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