Re: [CAD_CAM_EDM_DRO] Mach3 & laptops

Well, I'm more thinking along the lines of a "smart" USB endpoint rather
than a USB endpoint that bridges to parallel output without maintaining
the original timing.

The way I interpret this, ArtSoft relies on some specific behavior of
the parallel port which is not guaranteed by the port's specification
and thus only works on some hardware not others. This does tend to be
troubling since it is difficult to guarantee it will work the way it
does without glitches or changes in the system. But hey apparently it
does work if you get the right hardware.

With a smart endpoint (custom microcontroller- not particularly
expensive), I don't see any reason the USB link would be unable to send
the data with timing. The question's whether a virtual parallel port
driver would be able to preserve the timing content Mach3 intended for
its signals when it dumps it to the virtual port. For an generic
virtual port driver, chances are very unlikely. For a port driver made
to consider the timing of the signals sent to it... maybe. Not only is
it uncertain if this could work but virtual port drivers need to be
redesigned for different systems (XP vs Vista) which creates
unreasonable maintenance problems. A Service Pack update could break it.

Stepping back though, this seems silly to try to do this anyways what we
need is a plugin that just talks to the USB endpoint directly, knowing
it's a USB device rather than a USB device secretly pretending to be a
parallel port through a virtual port driver. For that matter the
stepper driver hardware should take in the USB cable and not route
through a parallel port, though for existing controller hardware it
might remain cost effective to go from USB to the parallel port on the
controller since it'd mean replacing it otherwise.

Danny

gcode fi (hanermo) wrote:

>
> This will work fine.
> The interface will be a bit slow, but more than good enough.
>
> The usb stuff referenced before was correct.
> Usb is not and cannot be time-correct. It is fast. So for video etc.
> that is a buffered non-time correct data stream its easy.
> Note that mach works like a video frame capture card at the frame buffer
> level, not the data storage level.
>
> Video is usually dealt with on a frame level, at 50 frames/sec, of about
> 70 kB each.
> Machine control is approx 1000 times faster (and smaller) - and a 3%
> jitter only 1% of the time makes it useless.
> Ms delays in networking and so on are insignificant, as they are in
> serial comms (at most about 2-3 Mbits/sec) with about 0.1 -1 1 ms
> latency typical serial comms.
>
> Machine controls deals with, in mach, a 40 usec pulse stream. About 25
> times faster.
> No usb converter solution will work. Technical reasons that cannot be
> changed, has to do with pc hardware etc etc.
> No "usb driver solutions" will work - mach runs the port directly
> without a driver at kernel level - thats what makes it work, real time,
> very well. It also means no sw plug will work in between.
> A usb solution that runs as a parallel port could be made - as far as
> anyone knows one does not exist at any price point. It would be
> specialised hardware, and not trivial, as from the pc hw point of view
> it would have to look like a bog-std parallel port. It would need a
> special card or motherboard. It would be very expensive to develop.
>
> Some intelligent non-real time usb controls work.
> They are complex, and almost ready after 16 months development.
> The most popular new one, seemingly best one, is the smoothstepper or SS
> from warp9.
>
> Some things are still hard to do with ss or don´t work - I believe
> integrating with a simultaneous pp for io, some probing, some mpg´s
> issues, threading seemingly is working from only about 1 month ago
> (after 10 months delays ...) and so on ... its very much more complex
> than you would think.
>
> At the moment any and all pieces exist. The sw is good. Almost anything
> can be done. Its not too hard, but there are very many bits and pieces.
> No easy, multiple, cheap, easy single box solution exists that supports
> multiple io, mpgs, threading, and analog io.
>
> Complex solutions that work fairly well seem to be integrating modio
> with parallel ports, ss with limitations, pp and pokeys, joysticks, pp
> with plc, extra io cards and so on.
> For 99% of use a ss seems to be good, fast, stable, by all reports. Its
> likely to become the best solution.
> At the moment, dual pc parallel ports is the easy, stable, fast
> reliable, for 99% plus of uses and basic io of about 15 bits/ports + 4
> axis.
>
> Probably a ss will surpass this soon.
>
> Danny Miller wrote:
> >
> > 'K looks like the system has an AMD Geode NX 1750 (1.4GHz) processor,
> > 40GB HDD, and 655360K RAM. Good?
> >
> > Well the price was right... free! Now I've got 3 systems I picked up
> > and the other 2 are totally obsolete/missing stuff. Huh now that I'm
> > looking at it this may need a new power supply it doesn't wanna start
> > after it's been running we'll work on that. But when I had it running
> > it loaded up and all, problem was it had a password-protected install of
> > NT so I couldn't do much.
> >
> > Danny
> >
> > gcode fi (hanermo) wrote:
> > >
> > > Danny - its a common problem.
> > >
> > > Over last 5- years, I have seen laptops tried by lots of people.
> > > Art, the sw creator, says laptops cause 99% of all support requests.
> > > Ie they are 100x more likely to not work than a given desktop.
> > >
> > > There are lots of good technical reasons, Jon E, who is very good at
> > > this stuff, explained some well.
> > > And the reasons really are technical ie valid and immutable.
> > >
> > > Conclusion - don´t try laptops, of if you do, many (exasperated)
> people
> > > will say we warned you.
> > > A mini-itx is good and cheap, like the shuttle boxes.
> > > Any cheap box is fine - add a video card if it does not work with
> > > onboard. Onboard may be fine, many are.
> > >
> > > At least 1 ghz processor, around 2 ghz is good.
> > >
> > > xp is easiest / most common. win2k may be ok. Few use it and driver
> > > support is so-so.
> > > Vista is bad but doable.
> > >
> > >
> >
>
>