John Kasunich wrote: > Something screwy there. You may have found a bug, or something may be > misconfigured. I don't have a servo machine here, but I might be able > to set up a "machine" using a simulated encoder. Jon Elson (the PPMC > guy) probably has more experience homing to index pulses than I do. > I did just review the homing code rather carefully, and I can't see > anything wrong. However, if the ppmc driver isn't resetting its output > to zero when it sees the index pulse, that might cause the symptoms you > are seeing. > > You might want to use halscope to look at the index enable signal and > the position feedback from the encoder to EMC. Trigger the scope on the > falling edge of index enable, and verify that position either is or > becomes zero at that moment. If it doesn't, its probably a driver bug. > I got all this debugged around Jan 8, 2007. I have sent Stuart a set of updated EPROMS for his encoder boards.
At the end of the debugging process, I observed some behavior that may have been the same as Stuart is describing. But, I was a lot faster to hit e-stop, so I did not wait to see whether EMC was going to stop somewhere within the machine's travel limits or not. The final problem turned out to be the polarity of the home switches was backwards. This was evidenced by the machine moving in a direction opposite to the sign of HOME_SEARCH_VEL. Well, instead of understanding why it moved the wrong way, I just swapped the sign of that parameter. It seemed to home kind of like I expected, but would occasionally (like 50% of the time) take off at a fast clip. Reversing the sensing of the switch's polarity fixed the problem, and made the home approach consistent with the HOME_SEARCH_VEL parameter. I have homed a number of times since then, and it has never taken off rapidly since. Does anyone know if there have been any changes to any code that might affect the homing process since 1/8/07? I don't believe my Bridgeport computer has been updated since then, and it is the only one with home switches or encoder index signals. Jon ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
