On Friday, 15 April 2022 19:23:49 EDT Torsten Curdt via Emc-developers wrote: > Hey there, > > I was wondering the following - and mainly really to understand how > LinuxCNC works. > Since I couldn't get a proper answer in the user chat I thought I would > try here. > > IIUC the GCODE interpreter runs in the non-realtime part. It sends the > step instructions to a card to execute the steps. This is obvious when > using a LPT port, but how does this work via Ethernet? > > Are the steps compressed into instructions and then applied on the Mesa > cards? > Poking around it seems like there are motion commands and status > commands? So it probably sends "go there" and "where are you" and the > card generates the steps required and reports back. Does that sound > right? Is there a definition of the protocol to look at? > I assume the code of what gets pushed to the Mesa's must be somewhere, > too. > > And now I hope I don't get lynched for asking: > How is that ethernet protocol different from the Mach3 ethernet > protocol? Are there significant differences between the protocols that > would prohibit LinuxCNC speaking the Mach3 ethernet protocol? > > Or maybe no one knows or cares? But I was wondering if > implementing the protocol could be another alternative to flashing > Remora to supported boards. > > While waiting for Mesa stocks to recover, I am really just curious to > understand the technical side of the LinuxCNC vs Mach3 comparison. > > cheers, > Torsten > First, I'll say I know very little about ethernet, other than I get the impression that it is not well suited to realtime control. That doesn't mean I don't use it, theres 6 machines here on my home net, but I don't use it for machine control.
Second, the only thing I know about mach3 is that it came in a starter version with a 6040 4 axis gantry mill I bought, and it only half worked in fits and spurts. I wound up junking the entire electronics control box because the whole thing stank of built by lowest bidder stuff. The power supply was rated at about 1/3rd of the amps it needed and was folding back from its nameplate 24 volts to around 13 volts when the 4th axis was plugged in. That was not enough to pick up the spindle motor when it was down. The vfd was not controllable by mach3, only by separate knobs on its own front panel, and even that was not a reliable method of starting or stopping it. Zero docs on the vfd unless you can read Chinese. It had a terminal marked rev but actually tossed a coin to see which way it ran this time. So I pitched the whole box in the trash trailer and built my own, using mesa parport driven hardware. Spindle motor was water cooled but a lightweight two bearing model, and the bearings started howling at about 5 hours. It was a 120 volt motor that flickered the garage lights, so I bought a 240 volt vfd and a decent 4 bearing motor. Wired that up 2 years ago. The vfd had an rs485 interface and runs better than direct control using that interface. ATM its torn down, getting the z and b drivers and motors replaced with 3 phase stuff. XY runs at better than 200 ipm now, and the new spindle is about a kg heavier than the old one so I'm hoping the 3 phase motor can pick it up faster than 20 ipm. The A/B rotary wasn't able to hold against any cutting forces, so that was worthless right OOTB, so I designed and printed a miniature harmonic drive with a 50/1 ratio. Slow, but holds, or turns under load, like you would expect it to. Linuxcnc is all synchronized, so when a fast axis and it moves at the same time, the fast axis slows down to stay in perfect synch when cutting threads and other such operations. I paid $1350 for it, and I've put another thou+ in it making it a usable machine. Had I stuck with mach3, I probably would have junked it all. One of the things you've got on this list is support for LinuxCNC from the people that have been writing it and improving it for at least 25 years now. Development is active. Very active. I now have 4 machines, all 4 basicly assembled from old raw materiel, 2 lathes, two mills. The big lathe, an elderly Sheldon 11x54, now about 80 years old, is actually being run by a raspberry pi, and doing tricks it could NOT do when shipped in the 1950 time frame. Why the pi? I wanted to see if it could be done, and its doing it quite well. Who am I? A 20 year retired television engineer with an odd history. I've an 8th grade education, but I'm also a CET, and I can discuss the theory of relativity with anybody that cares. Now a widower, and 87 years old. My mother was the only girl in the 1929 class on Aviation Technology at Des Moines Tech High school, and if she didn't know the answer, she knew where the county library was, so in the 2nd grade, I asked her what gravity was, so I was doing McGuffies Readers in school, and reading high school physics textbooks at home after school. And we still can't merge gravity into a Theory of Everything 80 years later. You will get answers from more experienced folks here, I'm a relative newcomer, discovering this list just before I retired in 2002. Oh, I've got oldtimers and nearly forgot, Welcome to the list, Torsten Curdt. Enjoy, take care and stay well. 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
