Re: [CAD_CAM_EDM_DRO] Code behind the Code

Wally6800@... wrote:

> Since I have been a member of this group, I have tripped over "G"
> Code . I have asked people who are considered experts in CNC
> programming,"What is the code behind the code?". They haven't got a
> clue as to what is going on behind the code. They just use it because
> it works.
>
> Where can I find a source for the code behind the code? What is
> really being processed in the conputer when the command G03 is being
> executed? Any body besides me interested?
> Is there anybody in this group that knows and would share that
> knowledge?

Sure, but it is NOT simple! First, there is an RS-274D interpreter,
that figures out what you have specified in the 'G-code' language.
Then, there is a section of code that figures out what moves are needed,
and interpolates smooth transitions between the consecutive moves,
and computes acceleration/deceleration ramps.
Finally, there is a real time section that computes where the machine
should be every tick of some clock, and on a servo system, computes
corrections to the velocity to reduce error.

If you want to look at code (warning, we're talking about 100,000
lines of C++) see
ftp://ftp.isd.mel.nist.gov/pub/emc/emcsoft/linux_2_0_36/emc-05-May-2000.tgz
This is in Tar-Gzipped format, for Unix/Linux systems. You can get
utilities that will open up these archives on a Windows PC.

Jon