Re: Parallel Port Interface

Hi Gary,
If you buy a pre-made and tested board to isolate the
parallel port that is good. If you wire one up there is a chance
your extra protection could do you in! I have found the parallel
ports on older computers can really take a licking. Watch out
for static build-up on your cloths. Don't hookup a computer while
either device is on. For years experimentors have hooked all kinds
of things to the parallel port without problems. Most motor control
circuits do have isolation as good as any printer. Some printers
have better circuits than others. But nothing does a computer in
more than a static shock. I had a spark jump into my camera port
and my computer shut down. I lost a Video card and a Serial board.

Bob

--- In CAD_CAM_EDM_DRO@y..., Gary.Rose@c... wrote:
> Hi,
>
> I'm putting together a small cnc system (Sherline based) and am at
> the point where I'm thinking about how to connect the parallel port
> to the stepper drivers, limit switches, manual jog controls, etc.
>
> Some schematics that I've found on the web show the step and
> direction and other lines directly connected to the parallel port,
> others use optoisolators (4N33 for example), others just have pull
up
> resistors, still others use buffer gates.
>
> Any thoughts? I'm leaning toward optos, because that's what I
know,
> but what do you guys think? Is it worth the trouble or not?
>
> Thanks
>
> Gary