Re: cnc pc board question

> >In these links it seems they call the card a controller card and

have

> >an external ampliphier or what we often call a driver.
> >
> >Seems the parallel port is free and you only need to buy the

driver

> >such as a Gecko. and that would be much less expensive.
> >
> >Am I missing something here ?
> >
> >
> Yes. If you need encoder feedback to the PC, the parallel port

doesn't

> have enough pins, and not a fast enough sampling rate, either, in

most

> cases. If you want to run many axes, have limit and home switches

and

> control
> auxilliary I/O (spindle forward and revers, coolant, etc.) you just

run

> out of
> signals. Also, if you want step pulse rates above about 25,000

steps a

> second for fast routers or mills with high microstepping factors,

you

> can't do it with software-generated step pulses.
>
> If you don't need all these features, and open-loop stepper drives

at

> modest speeds will work for you, then there's no need for the
> "controller" board.
>
> Jon

I got it, Thanks.

It is not a replacement for a Gecko or Xylotex, but an enhancement to
the PC, maybe a necessary item more than an enhancement.

Dave