Sounds like it is time to go back to your homemade 90 count encoder. If you just intend threading and not a rotary axis with positioning, then it should work well.
Steve Stallings > -----Original Message----- > From: Steve Blackmore [mailto:[email protected]] > Sent: Sunday, August 16, 2009 8:42 PM > To: EMC2-Users-List > Subject: Re: [Emc-users] Realistic spindle encoder count for > parallel port? > > On Sun, 16 Aug 2009 12:10:50 -0500, you wrote: > > > >OK, base period is 62.5 us. For safety, we should never > have encoder > >counts coming faster than twice that period. > >So, that is 125 us or 8000 Hz. Just to pick round numbers, > 3600 RPM is > >60 rev/second, or 16.67 ms. So, we can read no more than 8000 > >counts/second, and need to fit that into .01667 seconds. 8000 * > >.016667 = 133. So, you need a 128 or 100 count/rev encoder. > Encoders > >are usually specified as cycles/rev (also written > pulses/rev) and that > >is 4 x less than the count rate. So, you need a 25 or 32 > cycle/rev encoder! > >That's why people use hardware assist to handle these > encoder counting > >chores. > > Looks like a Mesa card may be a good bet, but... > > $199 + 22.5% import duty + carriage + 15% VAT = a lot :( > > I wonder how well I can get away with 1 pulse per rev? > > Steve Blackmore > -- > > -------------------------------------------------------------- > ---------------- > Let Crystal Reports handle the reporting - Free Crystal > Reports 2008 30-Day trial. Simplify your report design, > integration and deployment - and focus on what you do best, > core application coding. Discover what's new with Crystal > Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
