[Emc-developers] starting discussion about complex I/O (tool changers, variable speed gearing etc.)

[Steve S. <ste...@ne...>]

Recently there has been much discussion on the IRC channel about how
EMC should handle complicated machine functions such as spindle
speed/gear changing and the various types of tool changers. The
discussion brought out lots of differing opinions and it was mentioned
that perhaps the discussion should be moved to the developers list to
widen the scope of input. Here is my attempt to summarize the issues.

The current state of affairs is that EMC can handle a few types of
speed control and tool change, but these functions are essentially
hard coded and not easy to modify or extend. The addition of HAL and
the possible addition of Classic Ladder will help but cannot solve all
the issues.

The original EMC design mandated that only one process was in control
of motion and I/O and that was the task module. For more complicated
issues task could issue an I/O signal and wait while an external
process sends a "complete" signal. This works fine for many things but
becomes an issue when functions other than cutting need to move the
machine axes.

Possible solutions might include altering EMC so that I/O can handle
motion or enhancing the interpreter to handle I/O.

To expose my biases, the latter makes more sense to me. Then we could
use the approach of writing macros to handle complex machine functions
without having to alter the main EMC code. Not to make light of this,
creating macro extensions of the type required is not a minor task.

Let the discussion begin....

Regards,
Steve Stallings