On Monday 11 October 2021 15:49:43 Chris Albertson wrote: > You could be correct. High impedance is a recipe for noise. > > I had suggested a resistive divider just because it is simpler. But > you are right about providing a ground path. A divider certainly > would do that. If an opto is really needed then use a high-value > resistor to ground to keep the line from floating and bleed off > static. > > I also don't like the idea of grounding the shield on the encoder end > as it makes it impossible to know the path from encoder housing back > to true Earth ground. It is "unanalyzable" (if such a word exists) > Running the shield to star ground point makes it easy to verify it is > correct.
+100 Chris. Run a separate ground to the encoder from the star bolt, and connect the cables overall shield ONLY to that bolt. If that encoder uses the shield as its ground connection, toss it in the out bin, and get one that does have a separate ground wie going into it which is isolated from the metalic case. I would also verify that the encoder has a good ground to its metalic housing. Painted brackets are a recipe for failure. As are metallic shaft couplers. The elastomeric coupler that came with my omron, failed a year ago, and the coupling is now a couple layers of heat shrink with the inside layer of thermal glue. If it fails, replace it with a fresh copy. 50 cents maybe. 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, 1940) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
