I agree with Eric, Many Sin - Cos encoders like SICK and Heidenhain output a DC reference voltage on the A- and B- signals and only the A+ and B+ actually change around the reference. Some encoders like Kubler I think have true complementary differential outputs. In either case the differential amplifier that receives the signals should be able to handle either case. I know this from first hand engineering experience with interfacing Sin Cos encoders to the industrial servo drives I helped develop for my former employer.
I do not know anything about what is inside the Heidenhain interpolation box. What we did was use ADCs and FPGA logic to do the sin - cos interpolation. The method we used was to first convert the sin and cos to the tangent which is the ratio of sin/cos then use arc tangent lookup. By using the tangent any amplitude changes from cable lengths or other common factors will cancel. It is assumed that the sin and cos inputs are both affected equally. Of course there is more to it because the tan function does not behave well for all angles, it goes to infinity as angle approaches 90 and 270 so you need to know what octant the encoder is in and also use the cotangent. On the other hand my Bridgeport series II Interact conversion which had a Heidenhain TNC seemed to have some comparators and logic to do interpolation and output a higher frequency AqB signal. The interpolation was not very fine, in fact it is 20 steps per 360 degrees of sin. - 5 steps per 90 degrees, fairly easy to do with comparators. Regards, John Figie On Sun, Sep 19, 2021 at 11:25 AM Eric Keller <keller...@gmail.com> wrote: > I don't think that's true that they have to be compliments. There probably > is a way to adjust the levels like I mentioned in my previous email. Is the > manual online, or did you just get a paper copy? I wonder if it's an issue > with the signals not being +/- with respect to ground. Is it a Heidenhein > encoder? > Eric Keller > Boalsburg, Pennsylvania > > On Sun, Sep 19, 2021 at 11:50 AM Curtis Dutton <curtd...@gmail.com> wrote: > > > Ok after thinking about it more, the interpolate is expecting that the > > incoming sin/cos signals a,a* are actual inverse values. however this > > encoder is single ended, it just has a and b signals. the a* and b* > signals > > are a sort of reference voltage and never change. I'll experiment with it > > some more tomorrow.... > > > > > > On Sun, Sep 19, 2021, 12:55 AM Curtis Dutton <curtd...@gmail.com> wrote: > > > > > It is an incremental. Magnetic sensor. Gear tooth with I think 256 > teeth. > > > One sin/cos cycle per tooth. > > > > > > On Sat, Sep 18, 2021, 10:56 PM Ralph Stirling < > > > ralph.stirl...@wallawalla.edu> wrote: > > > > > >> A lot of very high resolution, and older encoders have > > >> sine wave gratings, which give sine and cosine waveforms > > >> on the A and B channels. These are connected to an > > >> interpolator box that contains A/D converters and logic > > >> to generate quadrature pulses. The higher the interpolation > > >> ratio, the lower the max velocity allowed. > > >> > > >> -- Ralph > > >> ________________________________________ > > >> From: Gene Heskett [ghesk...@shentel.net] > > >> Sent: Saturday, September 18, 2021 5:22 PM > > >> To: emc-users@lists.sourceforge.net > > >> Subject: Re: [Emc-users] Heidenhain IBV 610 troubles > > >> > > >> I don't think you have an encoder, but a resolver. If you are getting > > one > > >> sinesoid per full turn, its a resolver. > > >> > > >> > Anyhow it doesn't work and I'm not sure how to troubleshoot the > black > > >> > box. I have the manuals and I have tried various combinations of the > > >> > dip swithches inside. > > >> > > > >> > does anyone have any troubleshooting tips or stories about their use > > >> > of an interpolater box? > > >> > > > >> > > > >> > Thanks, > > >> > Curt > > >> > > > >> > _______________________________________________ > > >> > Emc-users mailing list > > >> > Emc-users@lists.sourceforge.net > > >> > > > >> > > > https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Femc-users&data=04%7C01%7Cralph.stirling%40wallawalla.edu%7C5a5b014bf3fc4481176208d97b03a93b%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C1%7C637676077932698528%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=sowEIC7aWNESysLAlCjxOMk84Inwx9pFjz4IRVk6vIo%3D&reserved=0 > > >> > > >> > > >> 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) > > >> If we desire respect for the law, we must first make the law > > respectable. > > >> - Louis D. Brandeis > > >> Genes Web page < > > >> > > > https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fgeneslinuxbox.net%3A6309%2Fgene&data=04%7C01%7Cralph.stirling%40wallawalla.edu%7C5a5b014bf3fc4481176208d97b03a93b%7Cd958f048e43142779c8debfb75e7aa64%7C0%7C1%7C637676077932698528%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=HxeTFPS47gukrRBopVJJ939Wg4sEwHPPRremv092Uy0%3D&reserved=0 > > >> > > > >> > > >> > > >> _______________________________________________ > > >> Emc-users mailing list > > >> Emc-users@lists.sourceforge.net > > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > >> > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
