Homing to index with steppers plus encoders is not going to work out of the box. Offhand, I'm not sure what it would take to make it work.
In the normal situation (servos plus encoders), emc's motion controller sees the index pulse and changes an internal motor offset accordingly. (basically, there is an identical "step" in both command and feedback) The new motor command and the new feedback position go into pid which gives a sensible motor command output. In your case, emc's position command is going to stepgen's position input, but stepgen's internal position is *not* reset by the index pulse. Stepgen will start slewing as fast as it can to reach that commanded position, which is probably very far away from its current position. The encoders follow the movement, and very quickly this runaway behavior is detected and treated as a following error. Besides simply giving up home-to-index, I see two general ways to approach the problem. First, use stepgen in velocity mode, so its input is velocity rather than position. This requires the introduction of a PID controller between motion and stepgen, much like there is between motion and the adc/pwm in a servo system. Second, to add an encoder-like "reset-on-index" to stepgen, which will involve a fair amount of C programming. Jeff ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensign option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
