Hey Todd. Was there a reason you went to a 7i85 rather than a 7i76 and 7i84?
All I can think of is you didn't need the extra io of the 7i76. So could do it with only two cards. Regards Andrew On Wed, Feb 12, 2020, 3:11 AM Todd Zuercher <to...@pgrahamdunn.com> wrote: > I'm using a 5i25+7i85s to run a large gang router with step/dir servos. > This machine has a lot of mechanical warts that have made getting a good > tune on the servos difficult. Having the encoder feedback made tuning a > little easier, and saves me from having to break out the o-scope to work on > it. > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: andrew beck <andrewbeck0...@gmail.com> > Sent: Monday, February 10, 2020 7:11 PM > To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] closing the loop in linuxcnc with a 7i76 mesa > card and step direction control > > [EXTERNAL EMAIL] Be sure links are safe. > > Awesome Todd > > What Mesa card did you use? And do you mind if I pick your brains on this > rather than reinventing the wheel. I would love to see a config that > works so I can compare it with what I have and make the needed changes. > > Also did you find the motion was uneven or did it just work as expected. > > Regards > > Andrew > > On Tue, Feb 11, 2020, 11:20 AM Todd Zuercher <to...@pgrahamdunn.com> > wrote: > > > It works very much similar to running them with an analog input. The > > encoder feedback can also be handy for double checking the tuning of > > your servo drives. > > > > You simply disconnect the position feedback from the stepgen and use > > the feedback from the encoders to connect to the PID and the joint > position-fb. > > > > You will need to tune the feedback loop, P=1000 will no longer be > > valid, and will likely have to be significantly less (guess 1/2-2/3) > > > > Todd Zuercher > > P. Graham Dunn Inc. > > 630 Henry Street > > Dalton, Ohio 44618 > > Phone: (330)828-2105ext. 2031 > > > > -----Original Message----- > > From: andrew beck <andrewbeck0...@gmail.com> > > Sent: Monday, February 10, 2020 4:46 PM > > To: Enhanced Machine Controller (EMC) > > <emc-users@lists.sourceforge.net> > > Subject: Re: [Emc-users] closing the loop in linuxcnc with a 7i76 mesa > > card and step direction control > > > > [EXTERNAL EMAIL] Be sure links are safe. > > > > Actually all I want to do is be able to home to index. Which I might > > be able to do now. As my servo can output a encoder Z pulse. > > > > And I want to have linuxcnc remember where it is if I disable the servos. > > That is now a massive deal but I get a bit sick of continously homing > > the machine every time I push the E stop in and disable power to > > servos. It would be nice to have the encoders still counting once the > > servos are disabled. ( drives would still be on just not running a PID > > loop.) > > > > And yes I was wondering what trying to run a PID loop on a position > > servo loop causes. > > > > Regards > > > > Andrew > > > > > > > > On Tue, Feb 11, 2020, 2:14 AM andy pugh <bodge...@gmail.com> wrote: > > > > > On Mon, 10 Feb 2020 at 10:30, andrew beck <andrewbeck0...@gmail.com> > > > wrote: > > > > On the back burner though I want to > > > "close the loop" back into linuxcnc with a 7i84 mesa card I think. > > > Has anyone done that before with a step direction control system? > > > > > > What do you anticipate gaining from bringing the encoders back to > > LinuxCNC? > > > > > > If this is a stepper system (it's not clear without inbox-mining) > > > then a PID will naturally attempt to run the motors faster, with the > > > reverse of the hoped-for result. > > > It is probably possible to simultaneously reduce the feed rate with > > > adaptve feed and then attempt to recover the lost steps, but I don't > > > know if anyone has tried that. > > > > > > If it is a step-servo system then the drives will already be doing > > > all that they can. You won't gain much from bringing the motor > > > encoder data in to LinuxCNC. > > > However, you might be able to gain accuracy by adding linear scales > > > to the system, and using the feedback from them to modify the motor > > > position commands. > > > > > > -- > > > atp > > > "A motorcycle is a bicycle with a pandemonium attachment and is > > > designed for the especial use of mechanical geniuses, daredevils and > > lunatics." > > > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
