Stephen Wille Padnos wrote: > Dave Houghton wrote: > > >> Hello Everyone >> >> In stepconf wizard and the page titled Basic machine information. Driver >> type has several options, when I choose Sherline, the Sherline mill does not >> work. Driver type - Other, works fine. >> >> I'm sure I've seem this problem mentioned before. Does anyone know for sure >> that the Sherline option tends not to work. >> >> >> > Yes, it is a known problem. There is no definitive documentation for > the Sherline driver on the web, so we don't have the right values to use > there. My understandign is that there are also several versions of the > driver board, which may need different timings. If you search the EMC > mail archives or on CNCZone, you should find a thread where someone > posted (apparently) correct timings. Some work has been done to make it > possible for stepconf to create Sherline-compatible configurations, but > this is only available when you compile the TRUNK version for yourself. > It's not a simple matter of changing a couple of numbers, the Sherline > drivers apparently require incredibly long step pulses, which aren't > possible with the type of configuration Stepconf generates right now. The > > >> Secondly is there any way I can find out when the Sherline option is chosen >> what values of Step Time; Step Space; Direction Hold, and Direction Setup >> are used. >> >> >> > The timing values for the driver option you choose are loaded into the > timing edit fields (even though they're greyed out). The actual timing > used will be limited by other factors though (to insure that there is > enough time for other processing tasks). > > Hope this helps > - Steve > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > I've posted previously on this topic, including the link to the guy who thought that step time and step space for the Sherline option in the wizard were inverted. Since then, I've done some additional testing, and no longer believe this is correct, as it produces missed steps in my setup. (Sherline PN 8760 driver box, one of the early ones, purchased in 2003)
In an attempt to understand this better, I decided to try the "reverse engineering" approach, and measured the actual step pulses generated by the Sherline supported EMC-BDI distribution, using the settings from the factory Sherline ini file (max velocity .36; max acceleration 5; scale 16000). http://imagebin.org/31335 The upper left image is jogging at max velocity, the upper right is a direction change, also at max velocity. The measured values are: Step time and step space, both about 80 microseconds, direction setup, 40 microseconds, direction hold 2.7 milliseconds. These are an order of magnitude longer than the other common drivers! Also of note, the direction change occurs when the step pulse is high, rather than low, as with EMC2. I don't know if this has any relevance, and hope someone more knowledgeable will comment. I then looked at the steps generated by the sample stepper XYZA configuration, using identical ini file settings. This is what I use and have found to be reliable over several years of use. (middle images) Step time at max velocity is just under 50 microseconds, step space is about 90 microseconds. Next I returned to the Stepconfiguration Wizard and tested settings similar to the ones I had measured. Starting with step time and step space of 80 microseconds, I worked my way down and found that between 44 and 45 microseconds for either parameter was where failure occurred. I then did the same for direction setup and hold, (with step time and space at 50 microseconds; (bottom 2 images)) and was unable to demonstrate errors all the way down to 200 nanoseconds for both. As an aside, the measured step time here is around 30 microseconds, despite the minimum setting of 50. In summary, for users of Sherline drivers who have problems with their machine setup, I think the best bet is still to use the sample stepper XYZA configuration, with ini file edited to match the factory settings. Stepconfig wizard with the above mentioned settings has worked with my testing, but should be verfied by others. Finally, I'm very much an amateur; if there are errors in my testing or analysis, please correct them. Hoping this will help someone HR Addendum I'm using Ubuntu EMC2 2.2.7. EMC-BDI testing was done on ? version 4.3, though I've since run the same test on 4.51with identical results. ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
