Homebrew PCBs

On 11 Jun 2013 05:21, "Andrew Hakman" <andrew.hakman@...> wrote:
>
> Most "USB to parallel" adapters do not do what you think they do. They
only
> work for printers, not general parallel devices. All the CNC machines use
> parallel so they can have a much dumber controller, and just diddle the
> bits of the parallel port for driving the steppers, and may rely on
> hardware interrupts and the very low latency of the parallel port for
> timing. I'm not sure why someone hasn't come up with a generic
> microcontroller based controller that does the same thing with the generic
> I/O pins, and takes the gcode, or something else at a 'higher level' over
> USB, as the timing over USB is not good enough to drive the motors
> directly. I guess it will happen sooner or later, with the parallel port
> becoming fairly scarce. Perhaps even an FTDI usb chip that has a bunch of
> directly controllable I/O pins might work (like are used in some common
USB
> -> GPIB interfaces)
>
> You can get PCI and PCI-e parallel port cards, and probably will be able
to
> for quite some time. I know some _very_ expensive devices that have direct
> parallel interfaces, and rely on a 'true' hardware parallel port to work
> properly.
>
> Andrew
>
I have a a modern PC with a PCI Express printer port. Even that fails with
some software as you can set the address to 3F8. I ended up running XP in a
VMWare virtual machine.  The virtualisation layer does allow the port to be
remapped to 3F8.

,
>
> On Mon, Jun 10, 2013 at 4:47 PM, Jim <n6otq@...> wrote:
>
> > **
> >
> >
> > Well, it uses a parallel port for connectivity.  That may pose a problem
> > in a few years when PC makers have utterly abandoned that interface --
the
> > machine should outlast a computer.
> >
> > It takes G code, so as long as you can find software on W1nd0ze (or
maybe
> > Linux??) to support that AND a parallel interface on a replacement PC,
you
> > should be good to go.
> >
> > Since I've recently had some really bad experiences with Communist
> > Chinese-supplied USB cables, I cannot blindly recommend using a
parallel-to
> > USB interface box/cable.
> >
> > I know that if I were in the market for something like this (and I kind
of
> > AM looking), I'd start with the software on my OS of choice first, and
then
> > go with a USB interface.  Finally the product differentiator would be
the
> > actual hardware.
> >
> > Basically if it won't support some flavor of *nix (I prefer a certain
> > bundled BSD Unix) and USB, I won't use it.
> >
> > 73
> > Jim N6OTQ
> >
> > >________________________________
> > > From: Dave <dave.g4ugm@...>
> > >To: Homebrew_PCBs@yahoogroups.com
> > >Sent: Monday, June 10, 2013 5:29 PM
> > >Subject: Re: [Homebrew_PCBs] Drilling machines, cheap Ebay routers
> >
> > >
> > >
> > >How do you compare these. I was looking at one of these:-
> > >
> > >
> >
http://www.ebay.co.uk/itm/NEW-3020-CNC-UPDATE-ROUTER-ENGRAVER-ENGRAVING-DRILLING-AND-MILLING-MACHINE-c1-/290928956948
> > >
> > >any idea what the difference is?
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
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