Stephen Wille Padnos <spad...@...> writes:
> I think there's something off in your calculations :) > > 2000 counts/rev * 3000 revs/min = 6,000,000 counts/minute > Dividing by 60 gives 100,000 counts/second at 3000 RPM, at 6000 RPM it > would be 200 kHz. Stephen, I forgot to mention that I have a 1:1.5 step up pulley driving the spindle. Motor top speed is limited to 3,540 right now, so that is where I got my 120 KHz. > Are you sure the encoders are up to it? Do you have differential or > single ended encoders? Is there noise filtering on the encoder lines? The encoder is a older Northern Precision Labs differential model. The line drivers in the encoder are DS8830N(s) - I checked the driver's output full wave propagation delays which are approx 35 ns max, which should be good for 250KHz. I could not find a spec sheet on the encoder itself. It is likely that the encoder has a bandwidth limitation that is causing my problem. I will look at the outputs on the scope tomorrow. Also, I connected my cable shield to power ground in the computer ribbon cable, so that may be causing excessive noise feedback. You have to jumper the Mesa 7i33 for differential inputs, and I think it has noise filtering. Thanks, Tom ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
