Re: [CAD_CAM_EDM_DRO] EMC interpreter was Re: BoBCad Question

In a message dated 5/8/01 9:32:45 AM Eastern Daylight Time,
ballendo@... writes:

> Randy,
>
> The EMC interpreter is certainly NOT a "hobbyist" component. It is
> derived from an old A/B control, and gets improvements as time goes
> on.
> I have mentioned before my frustration that codes which have BECOME
> the "new" standards in the marketplace are not generally respected by
> EMC, which has continued the practice of "re-inventing" the Gcodes
> used, in an independant NIH way. (Not Invented Here. Also known as I
> Can Do It Better My Way; ICDIBMW?) This is a typical CNC controller
> programmers' affliction, apparently...
>
> Last I looked, it was missing some "commercial" capabilities
> (branches, subroutines, etc., but my understanding is that these have
> been(or are being) added by work-around methods. (Ray?)
>
> The set of G code supported is extensive, and does include the
> standard G80's canned cycles...
>
> Hope this helps.
>
> Ballendo
>

Ballendo:
It was / is the missing features such as subroutines, etc., to which I
was referring when I said it was a hobbyist type interpreter. Now that you
tell me it came from an old Allen Bradley control it makes more sense as
those older Allen Bradley controllers were seriously behind the times with
respect to anything other than the bare bones G-codes and in many cases did
NOT support the extended features.
This is one of the main reasons those very A-B controls are being
removed from the machines on which I am working and we are replacing them
with PC based controls using CNCPro which does have most of those features.
In this case the radius compensation doesn't present a big problem as that
feature on the old A-B controls of this customer never worked properly anyway
and they just do the toolpath in BobCad. The most important features were
the subroutine capabilities, scaling, and look ahead execution. All of which
CNCPro does very well.

My only real complaint about any of these is that there doesn't seem
to be any provision for genuine closed loop operation or real servo motor
operation. I know that EMC is supposed to support servo control but have
heard that is doesn't work very well. I have downloaded a copy of EMC and am
working on a prototype control using it to see what features are really there
and if a true servo, closed loop system can be developed around it. Right
now I am having to use the StarCam driver cards which convert the
step/direction signals to +/- 10vdc for servo drive control.

Please keep in mind that I am fairly new to the PC based generic
controller. For the last 17 years or so I have only worked with the
proprietary controls installed by the MTB (machine tool builder) and I guess
I was looking to "have my cake and eat it too." Trying to find an
inexpensive software package that would have all of the extended features and
include closed loop and servo control.

The goal is to be able to build a control that can be retro fit to a
machine and, including the installation, only cost about what the proprietary
controller cost before installation or less.

Regards,

Randy Abernathy
Woodworking Machinery Specialist
4626 Old Stilesboro Road NW
Acworth, GA 30101
Phone / Fax: 770-974-5295
E-mail: cnc002@...


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