Re: [CAD_CAM_EDM_DRO] Re: Re: BDI and servos

At 19:27 12/7/2002 -0600, you wrote:

> > Â Â From: Bob Simon <bsimon@...>
> > Subject: Re: BDI and servos
><s>
> > How does EMC handle long streams of cutting data? Can it command
> > non-stop motion continuously from the hard drive or just the physical
> > memory? I can't seem to find any specifics on how EMC handles long
> > programs.

-------------------<snip>-----------------------

>I believe that file size in Linux is now up in the terrabyte range so you
>shouldn't be able to write a file that is oversize. Getting it into the
>interpreter is simply a matter of saying, "run this file." Since we
>have multiple processes running at the same time, the interpreter is
>connected directly to the file to run. The file is not passed through
>the user interface or anything else.

--------------<snip>------------------

>His suggestion with respect
>to maximizing the number of blocks that the EMC could read was to
>minimize the code that the interpreter has to read/parse by taking
>advantage of the modal nature of many of the g=codes.

That pretty much covers it! Sounds like profiling won't be much of a
problem with EMC. I'm familiar with minimizing G code. I already do that to
minimize transmission times on my ethernet/machinetool connections.

I have one question. Are there user available (.ini file?) parameters to
establish where the controller breaks smooth motion and applies a
deceleration/acceleration before continuing with the next block? Many
controllers call this "auto exact stop" or something like that. The
parameter usually represents an angle (deg or rad). If this angle is
exceeded, the controller will insert a standard end of move deceleration
and accelerate in the next move. I've seen more complicated schemes that
adjust the decel/accel proportional to the departure angle. One system even
uses an angle table. Most proportional schemes seem to be overkill...IMO.

I'm really looking forward to playing around with EMC. I've been around CNC
equipment since the late 70's and have retrofitted PC based controls on 7
machine tools. I don't have the raw programing skills needed to create my
own controller software. EMC's configurable characteristics make all the
basic stuff available with room for customizing.

-Bob