Working on my 8 head machine refitting. The machine had been previously configured using a Mesa 5i25+7i85s doing closed loop step/dir control with encoder feedback of 3 servos(xyz). (Other miscellaneous gpio was handled on an ISA card.) Power for the Mesa 7i85s was through the cable via the 5i25.
With the update, the ISA card was replaced by a Mesa 7i84, and 7 additional step/dir outputs added using a Mesa 7i88. The new machine configuration is using 2 of the old servos to control the either end of the Y gantry (previously only 1 servo), and 8 closed loop steppers have been added for each of 8 Z spindles. It appears that adding and powering the 7i88 from the 5i25 has put too much load on the 5v supply from the 5i25. Now, when the servo drives are not powered I am having trouble with the encoder feedback running away. I don't think this was a problem previously. When the drives are powered they add to the 5v that supplies the encoders and the feedback is steady. My 1st question is how large of a 5v supply should I add to power the 7i85s and the encoder feedback? Should I power both the 7i88 and 7i85s using this supply or keep one powered from the 5i25? Would powering from a USB port be sufficient? Next question while I setting up and trying to tune the gantry servos, I found that I was having trouble with the position feedback from the Mesa stepgen getting out of sync with the feedback from the encoders if the drives were ever disabled. Then when I am trying to run closed loop using the encoder feedback, if the drives are disabled, I have trouble with joint following errors when re-enabling them. Any suggestions for this problem? I believe the problem is the gantry is going out of alignment when shut down and there needs to be some provision for resyncing them when they are re-enabled. But I'm not sure what steps need to be taken to do that. Rehoming might be an option (but not what I'd prefer), but I can't even turn the machine back on (F3) without closing and restarting Linuxcnc. Todd Zuercher P. Graham Dunn Inc.<http://www.pgrahamdunn.com/index.php> 630 Henry Street Dalton, Ohio 44618 Phone: (330)828-2105ext. 2031 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
