Terry wrote: >Hi > >I have a Bridgeport Boss 5 retrofitted with an Ah-Ah system (stepper) >and I am going to keep the drivers and change out the software with >EMC (still using steppers). >I am a servo person so be kind when answering the following two >questions. > >1. Is there an advantage to using a board from mesa vs parallel port? > > Software stepping through the parallel port can come close to the maximum the drivers can handle. A Mesa card will definitely be able to reach the maximum the Ah-ha drivers can do, and much more if you decide to upgrade later (to faster stepper drives or to servos).
Out of curiosity, do you have the Ah-ha PC plug-in card? >2. What do these numbers mean in the EMC world?: > >6 us minimum step pulse width > > This means that steplen needs to be 6000 or higher (that's 6 microseconds, expressed in nanoseconds) >15 us off time > > This probably means that stepspace needs to be 15000 or higher. >capable of 45,000 steps per second > > You will need to set your velocity limit such that 45000 steps/sec is not exceeded. So if you have 10000 steps/inch, you will need to set the velocity limit to 4.5 IPS. This will need to be lower if you need to use backlash compensation, since the backlash accel is added to the trajectory planner accel. These specs don't say what the "dirsetup" and "dirhold" times should be, so I'd set them to the same as stepspace, 15000, to be safe. These are the times to wait after changing the direction output and before issuing a step, and after issuing a step before changing direction. Hope this helps - Steve ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
