Andy Holcomb wrote: > What resolution of encoders have should I use, my first thought is as > high as possible, is my logic wrong? If you are going to use Gecko 320's and software step generation, then your logic is indeed wrong. Depending on your software and CPU choice, software step generation maxes out at 40 - 50 thousand steps/second. Assuming a 5 TPI leadscrew with the encoder directly driven from it, and 100 IPM rapid feeds, then you have 500 RPM on the screw. If the encoder has, say, 1000 cycles/rev, that gives 4000 counts in quadrature, so you have 500 * 4000 = 2,000,000 counts/minute, or 33,333 counts/second. That is nearing the limit of software. If you wanted higher encoder resolution or higher rapid feed rates, you would be out of luck.
If you are using hardware step generation, or get rid of the steps entirely, like with my PPMC or universal PWM controller system, then it is not a concern. Higher encoder resolution leads to a stiffer and smoother servo response, in general. Jon ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
