Fiber optics is not hard to use. One of the easiest systems is the one used for audio cables in your TV set and stereo. they call it Toslink digital audio or S/PDIF. You buy the cables with ends attached at Best Buy or way-cheeper at monoprice.com Using a consumer cable makes it easy to buy and cheap.
The sockets you need on both ends are active 5 volt devices that act like TTL buffer chips or like opto isolators. Place a 5V logic signal in one end and it comes out the other. The sockets are mass produced for the consumer market and are not expensive, about a buck each end. Can go about 20MHz Toshiba makes them and I'd guess others too. Digikey, Mouser and other sell them. They work EXACTLY like opto isolators. There is another kind of fiber you can buy cheap and easy that is intended for Ethernet. This is another mass market product that is easy to find. Bt you can't cable the cables at Best Buy and it costs more but this system goes up to 1 GHz if you buy the right kind You want a system where the cables are available at retail outlets and are already cut and terminated at each end. Toslink uses cheap plastic cable and is limited length. But I've used the Ethernet kind and we bought it on a two kilometer spool. Terminating bulk glass fiber is a skill, about as hard as hand soldering BNC or N connectors on coax. Possible the BEST why to use fiber for CNC that would require zero modifications and using only off the shelf stuff is to get an Ethernet linked Mesa FPGA board and use a fiber segment to connect the Mesa card to the PC. But WHY??? Cat 5 wired Ethernet is already galvanically isolated using tiny transformers on each end. THAT is one of the best parts of Ethernet. But fiber is even lightening proof if you need that. On Thu, Apr 20, 2017 at 11:51 AM, Gene Heskett <ghesk...@shentel.net> wrote: > On Thursday 20 April 2017 11:22:03 Todd Zuercher wrote: > >> Fanuc has been using fiber optic connections for more than 30 years. >> And I work with an old SCM machine with a Num 1040 control that has a >> bank of fiber optic remote io that is one of the things holding me >> back from trying to convert it to Linuxcnc. >> > This has been a wish of mine for a long time. We need some cheap stuff > that can be the equ of an opto-isolator, but with a piece of glass or > plastic fiber up to several feet long as the optical media between them. > With power on the rx end, signal losses in the plastic fiber could be > easily compensated. I can visualize stepper drivers incorporating it, > probably at no more cost for the pair of fiber sockets than they cost > for the full opto-isolation BOM right now. > > All we would need would be an HE IR LED with a molded in funnel to guide > the fiber tip to the chip face in the LED. Some sort of a jacket on the > fiber to prolong its life if rubbing on something, or to prevent optical > crosstalk would be needed. The major design problem AISI is in gripping > the fiber to anchor it at both ends, with long term gripping pressure > imprinting itself on the fiber creating radiation leaks. Even glass > will do that, but usually over time frames that exceed the life of the > rest of the machine since technically, glass is a super-cooled liquid, > flowing visibly over the lifetime of the observer. > > The led makers have now had 40+ years to design such a package, and I > fail to understand why it has not happened. > > Or has it, and I missed the announcement? Thats a plausible excuse given > my age and retired status. If anybody would have it on this side of the > pond, digikey, and I've only found one candidate so far. Intended to be > a remoteable indicator, the led is conventional shaped, available in > several colors. Pricing starts at $2.15 with a 6" light pipe, Available > up to 3940" long. :) With the far end of that pipe facing into an > avalanche mode transistor, mounted exactly the same as the led, and > substituted for the BOM that puts the opto-isolation into the stepper > drivers input circuits, it ought to be essentially free! What sort of > speed would have TBD. But I'd certainly have to think its faster than > the 200 to 300 kilohertz we can now drive a $35 M542 stepper driver. > > Look at <http://www.bivar.com/portals/0/products/FLPRX.X-XX.pdf> > > And see what you think of it. > > One of those in red led, looking at one of these: > > <http://www.everlight.com/file/ProductFile/PLR135-T9.pdf> > > Would I think, be a good test bed. Need some smd bypassing of the rx > supply, and I'm not sure what buffering might be needed to make it > actually drive the opto's in the stepper driver. Pulse time distortions > are quite small and the data rate can be as high as 16 megabaud. > > Now if I can find where to source the fiber cable it uses in say 10' > pieces, I could try it out in this lathe conversion. With 10 40" > assemblies, I could put feet and sheet metal between the pi-7i90 and the > noise makers already installed. With 30 of them I could replace the > copper leaving the pi's box, except for the power cord, with fiber, and > enjoy the peace and quiet. > > And I've got Dennis Strander at DigiKey furiously sending out requests > for more info. W/O the fibers, we're under a $5 bill a connection so > far. I can live with that. We'll see what falls out of my email box in > the next few hours. > >> ----- Original Message ----- >> From: "Gregg Eshelman" <g_ala...@yahoo.com> >> To: "Enhanced Machine Controller (EMC)" >> <emc-users@lists.sourceforge.net> Sent: Thursday, April 20, 2017 >> 4:39:08 AM >> Subject: [Emc-users] Fiber optic control for CNC >> >> Looks interesting. Can't have a ground loop when there's no wires. >> http://hackaday.com/2016/03/20/add-fiber-optic-control-to-your-cnc/ >> >> ---------------------------------------------------------------------- >>-------- Check out the vibrant tech community on one of the world's >> most engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> ---------------------------------------------------------------------- >>-------- Check out the vibrant tech community on one of the world's >> most engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > 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) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
