RE: Re:EHP External Hardware Proposal

> -----Original Message-----
> From: Ian Wright [SMTP:Ian@...]
> Sent: Wednesday, February 02, 2000 6:11 AM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO]Re:EHP External Hardware Proposal
>
> From: "Ian Wright" <Ian@...>
>
> Hi,
>
> Ok, you've got me interested but there's one thing I can't quite
> understand
> yet - if you are using an external 'black box' to control the motors,
> where
> is the logic that controls the speeds of the various axes so that 1000
> assorted 'X' pulses plus 1000 assorted 'Y' pulses produces a perfect
> circle?
> As I see it now, EMC or its windoze equivalent does all the working out of
> pulse timing to ensure relevant positioning of the axes but, using an
> external box, this function would somehow be transferred outside the PC.
> For
> this to happen, the external box would seem to have to be intelligent
> enough
> to be able to work directly from something akin to a g-code file and, if
> so,
> what is the function of the PC in this now? Is it just a storage device
> and
> is the external hardware really just a kind of stripped down version of a
> completely stand-alone machine controller?
>
> Ian
> --
> Ian W. Wright
> Sheffield UK
>

The external box, in this case, would have its own profiler, clock
and PID. This is how the Galil (and a dozen other) boards work. It works
well, but most of the boards have a proprietary communication language.
Instead of G-codes, you get Galil basic or something similar. These are a
pain in the butt to write interpreters for, as I found out. Some of the
boards communicate directly in RS-274D (G-codes). All of them are horribly
expensive. My Galil board with driver software and a breakout board was
about $2800.

Mitsubishi has one just for CNC that uses G-codes. Last time I
called them for a wiring diagram they quoted $115. I didn't even bother
asking about the CNC board.

Doug

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