Re: Thoughts on Gcode interpreters and CNC controls....

Doug and the Group

There would be a number of ways this can take place:

1) Sounds as though you are describing "exectuting the code" and
buffering up the resulting 'bit patterns' that are 'played to the
motor controllers in comtrolled timing.

2) Another would be compiling each GM code line to an easly
interpreted format, no longer in ASCII character (text or numerals)
but in, for instance status bits or execution vectors and numericals
in long integer format. (precompiled as program downloads)

These records or instructions then execute as the the machine is
controller. I should be able to execute ahead of motion and buffer
up some the 'time-sliced' positon information to sent to the motor
drivers in an even timed fashion. If the motor drivers are updated
on a RTC interrupt basis, then the 'highlevel' operations will run in
the remaining time gaps.

It's do-able then not to get the micro dwells in the controlled motion

Stan, KO6YB

--- In CAD_CAM_EDM_DRO@egroups.com, dougrasmussen@c... wrote:
> Group,
>
> Since there's a fair amount of CNC knowledge in the group I'd like
to
> throw out a topic for discussion.
>
> A typical CNC controller operates on Gcode programs in what would
be
> called an interpretive mode. As opposed to having an already
> compiled CNC program to work from. In other words it scans through
> the program as it's executing it and forms the motion commands in
> real time. Sometimes it's obvious that this method slows down
> program execution, especially when you're trying to do continuous
> contouring using cutter comp on slower controls. An example would
be
> Ahha, I saw a wood router guy trying to contour with cutter comp
and
> it was a disaster because of the micro dwells between code blocks.
>
> My question is, why don't controls have an option to pre-scan a
> program and by accessing the tool and part offset tables pre-
calulate
> all the cutter paths so that when actually cutting all the
controller
> has to do is deal with interrupts and motion control? Or do some
> controls have that ability? I've asked this question to a number
of
> sales engineers at trade shows, but was never sure any of them
> understood what I was asking. The nearest I came to getting an
> answer was from a Mazak engineer who thought Mazatrol had something
> like that.
>
> Any thoughts?
>
> Thanks,
>
> Doug