On 15 May 2010 11:56, Viesturs Lācis <viesturs.la...@gmail.com> wrote: > > I had a thought about that and there is one BUT... I am going to use > stepper motor to control the rotary axis and as far as i know there is > only one way to create a closed loop system - EMC outputs PWM signal > and receives encoder data and then there has to be PWM-to-step signal > converter.
There are people running closed-loop stepper systems. One way is to use a velocity-mode stepgen and to pass the output of the PID as a velocity request. It would also be possible to use a very slow (possibly integral-only) PID as an added-on offset to a position command. You can use an absolute encoder without needing to be closed-loop, though. You could use a constant term, calculated at boot time as an offset between current stepgen position and current position as measured by an encoder and just add that on to the position reguest before passing it to the stepgen. It would seem a waste to fit an absolute encoder and then to only use it for a millisecond a day though. You can use an absolute encoder without needing to b -- atp ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
