Re: First time EMC user (introduction)

[Jon Elson <elson-at-pico-systems.com>]

Richard Everett wrote:

So Jon, how does your universal stepper controller interface with EMC?

 
The interface is by the parallel port, and it uses the IEEE-1284 protocol for speed.

 How does EMC tell the X axis to move some amount and that get translated through the parallel port to your controller?

It reads encoder counters to find the machine position (if there are no encoders, it counts the step pulses), and
then computes the velocity needed, based on planned velocity corrected by the position error at the last sampling,
and sends that velocity to the step rate generators.

 Did you write a driver for EMC and your card? 
Yes, and it should be on the very next EMC BDI cdrom.  There was some problem in the
Linux install under some particular hardware combination that has delayed the production
of the CDs.  But, they should be coming out within a couple weeks.
 Sounds interesting, and I could still use the Gecko drives.

Yes.  You could also arrange it such that the position fed back to the CPU, too, and reduce the gain on
the Gecko, so it acted a bit like a velocity servo amp, but the position loop was including the EMC CPU.

Jon