And here are links to those Digi-Key pages: The encoders: http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT102-V%20KIT http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=AMT103-V
And the "lump" line driver cables (which you will almost certainly want): http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-102E-10 http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=us&keywords=CUI-103E-10 And the "lump" line driver cable data sheets (such as they are): http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-102E-10.pdf http://media.digikey.com/PDF/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/CUI-103E-10.pdf (BTW, those "lump" line drivers are pretty cheap, and might come in handy anywhere any single-ended TTL encoder needs a quick-and-dirty conversion to differential line drivers. Just cut off the socket and wire the "lump" to whatever you like. Viola!) As far as resolution, they are all the "same", in that they are DIP switch selectable in 16 steps from 48 PPR (30000 RPM) to 2048 PPR (7500 RPM), in both binary and decimal resolutions, as per this table: http://media.digikey.com/pdf/Data%20Sheets/CUI%20Inc%20All%20Brands%20PDFs/DIP_switch_settings.pdf I would guess that the finer settings might exhibit hunting more? And that decimal settings might hunt more than binary settings? Dewey, what resolution are you using? Are you using only quadrature counting? Have you observed any hunting while quadrature counting? Have you ever tried using single-phase counting and did you ever see any extra counts? How many different resolution settings did you try if you ever went looking for hunting or extra counts? Again, the "extra" counts (if any) are not supposed to be a problem (numerically, at least) as long as they are counted using the quadrature method. The jury might still be out on position-servo-loop closure, which is why I am trying to gather information from those who have actually used them. For those on the list who have more machining background and maybe a little less electronics background, what we are talking about here is that if you take any traditional optical encoder and a CUI AMT-102-V (or CUI AMT-103-V) capacitive encoder, both with the same resolution, and rotate them both (very, very slowly)... The optical encoder will count like this: Zero... One... Two... Three... Four... Five... But the AMT-102-V might(?) count like this (balanced?): Zero... One... TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree Four... Five... Or it might(?) count like this (unbalanced low?): Zero... One... TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree Three... Four... Five... Or it might(?) count like this (unbalanced high?): Zero... One... Two... TwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThreeTwoThree Four... Five... (Digital logic experts please note that I am not saying anything special about the two-three transition, I just picked it at random for convenience in this example.) And if the counting business isn't bad enough already, it might be affected by how eccentric the shaft/disc is relative to the body. (Remember, this is a kit-type encoder, it has no built-in ball bearings.) So there might be an error variance that repeats every 360 degrees. Servo loop experts might be driven nuts by this, or they might just say widen the deadband and live with it. But that might not make the problem go away completely when the following error is near the upper limit, because you can't be sure (or can you?) when you'll hit another hunting spot. Or maybe the problem appears worse when following error is very small? Anyway, for those who are still following this thread, sorry if I've beaten the subject to death, but a low-cost encoder might be a good idea, provided it doesn't come with a whole new set of gotcha's; which is why I'm so interested in hearing from those who have actually used them, especially in a position servo loop. So I'll take any information I can get, and I can take this off-list if everyone is tired of it. Thanks, Kim Jeff Epler wrote: > On Tue, Jan 12, 2010 at 08:47:28AM +0200, Roland Jollivet wrote: > >>What's the resolution etc. of your encoder, and what did it cost? >> >>They seem reluctant to simply list pricing. > > > I don't know about pricing direct from CUI, but digikey sells them > starting at single quantity and will happily display the price ($29.95 > qty1, on down to $18,900 for 1000 of them). > > Jeff > > ------------------------------------------------------------------------------ > This SF.Net email is sponsored by the Verizon Developer Community > Take advantage of Verizon's best-in-class app development support > A streamlined, 14 day to market process makes app distribution fast and easy > Join now and get one step closer to millions of Verizon customers > http://p.sf.net/sfu/verizon-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ This SF.Net email is sponsored by the Verizon Developer Community Take advantage of Verizon's best-in-class app development support A streamlined, 14 day to market process makes app distribution fast and easy Join now and get one step closer to millions of Verizon customers http://p.sf.net/sfu/verizon-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
