On Saturday, 16 April 2022 14:33:25 EDT Torsten Curdt via Emc-developers wrote: > > > Does that mean it requires 4 inputs per motor? Or would this > > > somehow be normalized into STEPs and DIRs? Or what does Linuxcnc > > > expect?> > > The encoders are quadrature, so the diff is low, but the splitter > > could easily turn that signal pair into a TTL level signal. In fact, > > and not for a 3 phase setup, I'm doing that conversion mid-cable on > > my Go704. Using $2.50 rs485 interfaces solder programmed for 1 way > > only signaling. > You provide the encoder signals via RS485 to LinuxCNC? > No. I am a CET, (Certified Electronics Technician) I simply used the ready made cheapest gizmo I could find for a differential to TTL translator, two of them making love in a teeny hammond diecast box was exactly what I needed. The fact that they were designed to do that in an RS485 circuit, and made in qty's resembling Orville R's popcorn made them ultra cheap. Orville Redenbacher being the premier brand of popcorn here in the states.
> > > The splitting would not work for the servos that have the driver > > > integrated though. > > > > Why not? > > There are no pins to connect to :) That I should point out, is generally NOT a problem for a CET. > At least not until one would "fix" that inside the driver itself. And I > am not so eager to do that. It might be difficult mechanically, but the points to grab ARE in the circuit. Generally useing a scope probe to help in identify them. > > > It sounds like the ideal LinuxCNC setup would be a very dump driver > > > (without encoder support) and a stepper/servo with just an exposed > > > encoder. And then have LinuxCNC take care of everything. > > > > > > Does that sound about right? > > > > See wiki.linuxcnc.org, > > Anything in particular? I've been browsing there for a while. > > > its been done around a decade ago. Nyquist related > > phase errors I believe limited the speed, but might work better > > feeding mesa stepgens and encoders since they're much faster than > > software. > Now I am confused. > > So that would NOT be a recommended setup? I think it would be good, given that todays hardware is considerably faster, Nyquist (time delay phase shifts) caused instability stuff s/b much less of a problem and I expect it would be quite easy to do today. Particularly if you pay attention to the addf order in the hal file. But, what the vendors are supplying today is 20x faster than early x86 stuff when that wiki article was written. About the only thing that might be a problem today is software stepping, and where my first mill ran all software on a shoelace budget and was hard put to move that mill about 8" a minute, that same driver kit is now moving a different mill at 200 ipm. That was then running on an intel atom board at 1.4 ghz, but currently has an off-lease dell with a 3ghz i5 in it, lots faster. Speed limit is the opto-isolators in the drivers, which are slow and start smearing the step pulses at about 250 kilohertz. So they are limited to around 200 kilohertz so they don't miss a step. > I am slowly running out of ideas what is :) Tell us what you want to do? Probably not me, but there are folks here with far more knowledge than I've experience with, that can give you an idea how to do it. 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
