On Sun, 2011-02-06 at 19:40 +0100, Sasa Vilic wrote: > Hello, > > I am considering using Mesa 5i20 board to drive my gecko stepper drives. > But, something was not clear to me: > > How EMC controls speed of axis/joint? Since emc module stepgen, and also > mesa stepgen are using pos-command and pos-fb for controlling joints, it it > not clear to me how EMC keeps constant speed of axis when that speed is > bellow maximum? > > I know that there is velocity mode in both modules (emc software stepgen, > and mesa hardware stepgen), but from what I saw, they both are using > position mode instead velocity mode, and yet emc can keep joints at constant > feed rate? Is there any manual about integration of mesa board and steppers? > > Thank you very much. > > Regards, > > Sasa Vilic
EMC2 computes a position solution every servo period. The servo period has a very definite and regular time interval. Velocity = distance / time, or V = steps / time, or V = steps / servo period. So stepgen gets a position input every servo period, but you also have the option to feed it a velocity and it will convert it into the number of steps (position) needed relative to the known period. As a side note, the position or position-from-velocity is set every servo period but the steps are sent, if we are talking about the parallel port, a toggle at a time (or a toggle with reset) with the base period. So the number of steps per servo-period are limited by the number of base periods per servo period. I don't know if you get a burst of steps or if they are evenly spread. v One Servo Per v SSSSSxxxxxxxxxxxx or SxxSxxSxxSxxSxxSx -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
