On Mon, 15 Apr 2024, Todd Zuercher via Emc-users wrote:
Date: Mon, 15 Apr 2024 19:27:19 +0000 From: Todd Zuercher via Emc-users <emc-users@lists.sourceforge.net> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Cc: Todd Zuercher <to...@pgrahamdunn.com> Subject: [Emc-users] Mesa Card Stepgens? I was working on this machine where I need a whole bunch of extra stepgens. I am using a Mesa 7i85S and a 7i88 connected to a 5i25 card. I was testing some of the stepper drives and I noticed that with one of the drive/motor combinations I am needing to use slightly longer step timing and lower max velocity. I thought that this was odd, because all of the drives, motors, and mechanicals are the same for all of the ones I was testing. The only difference is that the slower one was connected to a stepgen on the 7i85S and all of the others are on the 7i88. So just for curiosity sake I checked the voltage at the input terminals of step/dir signals of the drive. On the terminals connected to the 7i88 I found +/-5v, and on the one connected to the 7i85S there is only +/-3v. This is the only difference I've been able to find between the different joints in question. Does it make sense that the voltages would be different on the step/dir outputs between the 7i85s and the 7i88? Does it make sense that the difference would cause a difference in the required step timing? Why might there be a difference between the output voltage on the two cards? Both cards are getting their 5v from the 5i25. The 7i85S is also connected to 3 step/gen servo drives and their encoder's feedbacks. Is it possible that the 5v drain from the encoders might be causing the lower voltage on the 7i85S's outputs?
I would check the 5V rail at the 7I85S card, and if its low, power the 7I85S directly from 5V rather the through the parallel cable. ALso the very first lot (many years ago) of 7I85S cards were built with DS34C87 drivers which do not have full 5V drive. If you have this card, you can get 5V drive by using single ended sinking outputs and 5V+ to drive step+ and 7i85s step- to drive step-
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
Peter Wallace Mesa Electronics _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
