I think the RC filter idea would work OK. Gear teach are after all a low frequency signal, so a filter made with a cap size for a corner freq of (say) 100KHz will keep RF out of the line.
That said the "correct" way to do this is with a pair of driver/receiver chips. If you use RS422 (that is a differential signal) you can likely go over a 1/4 mile of trusted pair wire. As for wire why not use Cat 6 or better for a machine shop cat-6 shielded. It is terminated in RJ45 and it's dirt cheap. And has enough pairs (4) for your use. Also I was reading LinuxCNC docs, it said a spindle encoder needs to be quadrature. You need two sensors for that phase A and B plus a third for the index. Cat 6 has four pairs so you can use the 4th for power to the sensors. As I said, the simple RC filter like you suggested can work but the "classic" method for use in a shop filled with high power machines is to use a differential single as it is immune to common mode noise, then use twisted pair in a sealed that is grounded on ONE end only, On Mon, Sep 12, 2016 at 10:43 AM, Gene Heskett <ghesk...@shentel.net> wrote: > Greetings all; > > I see by the spec sheet that the allegro 667 gear sensor can sink up to > 25 mills. > > But with 3 such sensors on the end of a long cable back to the breakout > board, probably 7 foot by the time I get it routed, I am concerned with > the potential for crosstalk noise in spite of putting a bypass capacitor > on the encoder itself. > > This noise would be reduced by a lesser amount of current. So, for those > of you using this device, what value is the resistor are you using for a > pullup at the breakout board? > > And if using a piece of idc ribbon cable, it seems to make sense to put a > grounded wire between each of the A|Z|B conductors, making that a 7 > conductor cable rather than a 5. I have around 90 feet of 26 wire ribbon > I can split off what I need from. > > Good idea? Or off the wall & probably will be plagued by noise if I shoot > for a 10 milliamp pullup with a 470 ohm pullup, or even 5 mills with a > 1k pullup. > > Time to assemble that motor driver box I believe. > > 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> > > ------------------------------------------------------------------------------ > What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic > patterns at an interface-level. Reveals which users, apps, and protocols are > consuming the most bandwidth. Provides multi-vendor support for NetFlow, > J-Flow, sFlow and other flows. Make informed decisions using capacity > planning reports. http://sdm.link/zohodev2dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports. http://sdm.link/zohodev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
