Hey Gene. Just reading your reply here.
So I have a 5i25 and 7i76 currently connected I'm running out of io, so am thinking of getting a 7i73 for the console buttons eg cycle start so that I can free up my 7i76 io for the toolchanger. And I want to bring my encoder feedback from my Chinese step and direction servos right back into linuxcnc. So need at least 3 more encoder counters. Also in the near future I will have a 4th axis on this VMC with a 5 axis trunion to follow soon after. But I can buy another card then if I need to. Though if it makes sense I can buy it now. All of these axis will need feedback right to the main control. (I'm sick of loosing position whenever I push in estop / turn off servo power to motor haha) On Sun, Apr 5, 2020, 8:11 PM Gene Heskett <ghesk...@shentel.net> wrote: > On Sunday 05 April 2020 01:29:50 andrew beck wrote: > > > Hey guys. Just getting back to this while we all have some free time. > > > > Todd could you please confirm what card you use for closing the loop > > back to the control when using step and direction control? I want the > > most encoders and general io I can get Ideally. Don't need serial > > ports etc.. > > Depending on the firmware you put in it, the 7i90 can have 4 to 8 > stepgens, and 4 pwm-gens, and 4 encoders. You can talk to it over spi, > or you could use a 5i25. And it has a 3rd 16 bit wide and faster means > if the parport is totally bi-dir. > > All its i/o, 72 pins worth, is a bit fragile, just barely tolerant of 5 > volts and to be safe around a box full of stepper drivers, needs 3 > 7i42TA's for protection, but that also makes hookup a piece of cake by > giving you the usual green screw terminals to wire it up. > > That is what I'm using to drive an 11x54 sheldon from a pi4, and I've > still enough i/o left over to handle a 6 pole turret mount. > > > On Thu, Feb 13, 2020, 3:13 AM Todd Zuercher <to...@pgrahamdunn.com> > wrote: > > > The machine I am using this on was already set up and running > > > Linuxcnc, but only using software stepping (but not using a parallel > > > port for the I/O). I was having a lot of trouble getting a good > > > tune on the servos as well. At that time the 7i85S, was the only > > > option for hardware step generation and encoder feedback. And since > > > the machine was already set up and running Linuxcnc I didn't need to > > > worry about hooking up other gpio. Unfortunately once the existing > > > PC dies, I will probably have to buy something else for the gpio, > > > because it is using a rather expensive ISA card for that. Not to > > > mention the fact that I can't seem to get a real time os newer than > > > our old Ubuntu 10.04 .ISO to run on that ISA/PCI slot motherboard. > > > I'll probably just end up buying a 7i84 and scrap all of the old IO > > > boards that go with that old ISA card, when that day comes. > > > > > > The 7i76 only has one encoder input and the 7i76e or any of the > > > other Ethernet cards didn't exist yet (at that time). The 7i84 is > > > a Smart Serial card and is only serviced at servo thread speeds, so > > > it's only good for gpio with no encoder inputs (the two MPG inputs > > > don't count because they aren't fast enough for servo use). I think > > > the 7i84 is pretty much exactly the same as the built in GPIO on the > > > 7i76. > > I've 2 of the mpja encoder dials, 100ppr style on the sheldons new front > apron so I can drive it by hand. Rigged up in hal for jog sizes > from .0001" to .020" per click on a 1-2-5 scale, which is fast enough to > hit either axises speed limits. But all that runs in a 200hz thread, not > in the servo thread. > > And I've still got gpio's, 30 or so that I haven't used. And if I > survive the virus, thinking of converting the step/dir steppers to > step/dir controlled 3 phase servo's. > > > > 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: Tuesday, February 11, 2020 7:30 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. > > > > > > 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. > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > 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
