Once have I a connection where only fast signal worked. In turned out the signals were coupled with a capacitor that was to small to pass low frequency. Of course no capacitor was designed into the system but a loose solder joint was acting like a capacitor. Actually what else is a cap, but two metal plates with a tiny air gap between them. The fix was easy, apply heat with solder iron. Once you know what look for it is easy to find.
It could be something like that, Some place there is an unexpected high pass filter or a low pass the shunts to ground or Vcc On Wed, Nov 1, 2017 at 4:25 PM, Eric H. Johnson <[email protected]> wrote: > All, > > > > A machine (table) that has been running for about three months has > developed > an odd problem in the last couple weeks. Not sure if it has been getting > worse or if just the nature of the patterns being run has made the problem > more pronounced. The machine is an XYYA configuration with a pneumatic Z, > and using mainly Mesa boards. The problem is in the A axis. It seems to be > losing encoder counts at very low speed, but not otherwise. It took a bit > to > track down because when I initially had it moving multiple rotations I > could > not get any errors running A by itself. Running with a feed rate in excess > of 20000 (Degs per min), resulted in no errors. Slowing down to 10000 > started to show a very small amount of error, and from 5000 on down the > error was very pronounced. > > > > The hardware is a Mesa 7i43 FPGA, 7i33 quad analog servo card and YEnc line > drivers. The table is 15' x 30', thus requiring line drivers on X and A, > but > for uniformity, were put on all four axes. The encoders are wired > differentially. The error is always in the same direction regardless of the > velocities used for the cw and ccw directions, thus would seem to be > dropping counts. > > > > I did not have a scope with me to check the encoder signals. While a low > probablility, I do have spare YEnc modules, but ran out of time before > trying to swap it out. I don't really see how this type of problem > (electrical) can develop over time, but do not see how it can be anything > else. > > > > Anyone seen anything like this when using that hardware? > > > > Thanks, > > Eric > > > > ------------------------------------------------------------ > ------------------ > 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 > [email protected] > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
