Re: [CAD_CAM_EDM_DRO] I'm curious

Randy:

> Mach has no idea where it is at it, only thinks it knows where it's at.
>
> I agree that Mach-X and Geckos work great but you are still open loop.
>

Actually, there are systems out there where Mach3 knows its postion and
will stop and trigger operator warnings if
the drive has faulted or is having trouble keeping up.. Mach3 uses a
MacroPump, this is a user writable code segment
that runs up to 10 times a second and can monitor system variables and
operations applying its own logic to the system.
This means there are those that have hooked up encoders, and 10 times a
second monitor the difference between encoder
position and actual commanded position. This can be considered a closed
loop. Closed loop circuits need not apply correction, in fact it is arguable
that applying correction is the wrong thing to do in such a situation, a
drive may, for example be out of postion due to grinding into something it
cannot cut, best to stop, shut off the spindle, perhaps lift it, and signal
the operator of an interference, than to press harder and eventually break
something.. (Not everyone would like that behaviour of course, but it is one
possibillity. ). I guess what Im saying is that the definition of closed
loop, in reality, belongs to the individual use of the unit and the unit
itself. Mach3 IS limited in this capability as it can only read encoder
inputs at a raw rate of 45Khz maximum. This , I believe, is only about
5000 - 7000 counts per second. This would be too slow for a fast servo
system, but for machines that need it and fall within certain unit
parameters, closed loop in Mach3 , is
a possibility.
Hopefully, Mach4 will have full closed loop capability, I'm working on
it.....

As to serial drives and such, you never know....the command stream of lines
and circular movement requirements may become available at some point in
future as Mach4's development moves forward....

Just to clarify.. ;)

Thanks
Art