andy pugh wrote: > On 22 November 2012 11:26, Dave Caroline <dave.thearchiv...@gmail.com> wrote: > > >> Current encoder inputs need 50% ratio >> Some cleaning/retiming required >> > > I can't decide if it is a special case of counter mode, or a whole new > component. > It actually gets fairly complicated! To handle the missing tooth, you need to have a tracking counter (or whatever) that keeps track of the recent time between pulses, so it knows how long a gap is going to be the missing pulse. When the instantaneous change in velocity is large, like at spindle reversal, then you are likely to miss one of those pulses. So, my guess is it can work well for a lathe spindle running at nearly constant speed, but may not work well at all for rigid tapping. I'd be real skeptical it could work at all in that case. Also, with a range of BASE_PERIOD timings, detecting the 45 vs 90 us pulse width might be a bit tricky. If used on a fast machine with a 20 us BASE_PERIOD or less, it should be fine.
Generally, I just don't see the advantage of going to a single sensor/single wire scheme when there are so many potential pitfalls. Anyway, it would take some serious work to make sure this is completely reliable. Most parallel ports have 5 input lines, so that should be enough for the E-stop, limit switches and leaves 3 for a quadrature encoder. One other comment, with a 90 us pulse width from the sensor, and assuming some reserve, so assume pulses should never come faster than every 180 us, that is 5556 pulses/second. If you assume a gear with 100 teeth, that is 55 RPS or 3333 RPM. So, this should work on most lathes with up to 100 tooth gears on the spindle, but might be a limitation on small mills. (Well, they might have fewer gear teeth, anyway.) Jon ------------------------------------------------------------------------------ Monitor your physical, virtual and cloud infrastructure from a single web console. Get in-depth insight into apps, servers, databases, vmware, SAP, cloud infrastructure, etc. Download 30-day Free Trial. Pricing starts from $795 for 25 servers or applications! http://p.sf.net/sfu/zoho_dev2dev_nov _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
