Re: Re:EHP External Hardware Proposal

I think the issue here is stepper vs servo thinking.

In the stepper case, the pulses typically are blindly put out by the software and it is assumed that the design is done
correctly. The steppers will move as commanded and all is well.

In a servo application the software "continuously" monitors the progress via encoder feedback and adjust the axis dynamically on
the fly to guarantee the performance.
Bertho
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> From: hansw <hansw@...>
>
> Hi Ian,
> reply in text
>
> Ian Wright wrote:
>
> > 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?
>
> As I see it, the PC will do the math, and send the data to the hardware, which will then control the motors.
>
> > 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?
> >
>
> No it will still be busy doing the math and keeping track of the external hardware's progress...
>
> No details yet, I have a few ideas about the whole handshaking and data transfer operation... The is also confusion about
> stepper and servo...
> Some people are wanting a "do it all" device. Myself I just want to control steppers.
>
> hansw