Re: [Emc-developers] [PATCH] abs spindle velocity pins

[John K. <jmk...@fa...>]

On Sun, Sep 29, 2013, at 06:45 PM, Chris Morley wrote:
> 
> 
> I mean if we wanted we could only have one spindle velocity output pin
> instead of fwd,rev,rps_out,rpm_out, spindle_on,brake_on,vel_cmd pins etc.
> It would just require the user to add half a dozen components to make
> them all work.

Actually two are needed:  spindle_on and velocity_command

All the others can be derived from those.  IMO, two are needed because
I don't want to rule out the possibility of "on but at zero speed".  For
example, during rigid tapping the velocity command passes through
zero.

As a specific example of why NOT to put all that in motion, consider
"brake on".  That is there because it was present in EMC1.  But what
are the actual requirements of a given system?  Maybe they want a
short delay before applying the mechanical brake?  Maybe a delay
when the brake is removed, before starting the spindle drive?  There
is a pretty good chance that the existing brake pin won't work for 
many users.  Better to get that logic out of motion and let the users
do what they need.

I like Steve Stalling's suggestion to make a HAL component that
generates the "bundle of signals" that you listed above.  Such a
component would be simple to load, and would compartmentalize
the spindle logic separately from the rest of motion.  A user could
easily look at the component and decide if it meets his needs or
if he needs to do further customization, either by adding more HAL
components or by making a custom version of the "spindle-bundle"
comp.

-- 
  John Kasunich
  jmk...@fa...