On Sun, 09 Jun 2013 18:14:16 -0500, you wrote: >On 9 June 2013 23:05, Gene Heskett <[email protected]> wrote: > >> >>> However, with the motor driver disconnected so there is no input from the >>> encoder, the output voltage steps at the C41 output aren't truly linear >>> either. >>> >Do you know that the C41 is completely linear? From what little I know >about it, >I would not be surprised if it is somewhat nonlinear.
They aren't. There was a long discussion on this subject years ago on the Mach group. Converting a PWM signal to a voltage seems to plot a curve as Gene has found, I seem to remember it was something to do with RMS? There are loads of references to the problem out there. Art's answer was to write a spindle calibration routine. It simply runs the spindle from zero to max speed and plots actual speed compared to commanded speed throughout the whole range and creates a table that is used to interpolate the correct output. To be honest, in practical terms it matters little if the speed isn't exact for most machining purposes. As long as the feed tracks the speed in feed per rev situations it's nothing to worry about. Steve Blackmore -- ------------------------------------------------------------------------------ How ServiceNow helps IT people transform IT departments: 1. A cloud service to automate IT design, transition and operations 2. Dashboards that offer high-level views of enterprise services 3. A single system of record for all IT processes http://p.sf.net/sfu/servicenow-d2d-j _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
