On Wed, 16 Sep 2009 12:16:02 -0500, you wrote: >Steve Blackmore wrote: >> On Tue, 15 Sep 2009 20:24:16 -0500, you wrote: >> >> >>> On Tue, 2009-09-15 at 11:06 -0400, Dave wrote: >>> >> >> >>> IMO you'd want it to be no more than a pulse wide or the threading may >>> start at any of the pulses that the index spans. >>> >> >> Strange behaviour? - It should start on either the rising or falling >> edge, if it starts anywhere else it needs fixing. >> >This whole thread is about using the SOFTWARE enocder counter (a HAL >component) for the >spindle position.
Is it? I started the thread :) All I'm personally interested in is threading accurately. As I understand it, it waits for an index pulse before starting a threading pass - I know that to be true, as disconnecting the index pulse - it waits forever on a G33. Then information becomes woolly - I guess it uses the quadrature count to get an accurate speed and adjusts the Z feed accordingly?? My 3 phase VFD driven spindle isn't capable of behaving like a servo, so spindle positioning is unnecessary for me. > It is software sampling of the encoder signals, so >the "rising edge" would be detected >at the first sample where index was noticed to be true. But, of course, >if the sample rate was slower than >the quadrature count rate, the encoder counter would not be able to >reliably count position anyway! >So, stretching the index pulse wider than one encoder count would not >actually help anything, unless >you were wanting to just sense the index pulse and ignore the quadrature >count. Not if the above is true? >All in all, I think the whole exercise is a big mistake. If you want to >use the software encoder counter, you >need a low resolution encoder, maybe as low as 25 cycles/rev, or 100 >quadrature counts/rev. 125 count (500 quadrature counts/rev) works fine here via parallel port. Steve Blackmore -- ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
