RE: [CAD_CAM_EDM_DRO] Mach3 & laptops

Danny:

You will find, if you use them much, that even the best of the USVB-to-serial converters are nowhere near as reliable as a "real" serial port. One of the best of them, believe it or not, is the Radio Shack model, but it still has issues with some equipment. I work in AV integration, and a lot of the equipment we service and program has serial ports, and it can be a nightmare sometimes to communicate using a laptop without a real serial port.

The program may not know the difference, as you wrote, but in many cases, the hardware it is trying to talk to DOES know the difference.

And Art Fenerty has stated that Mach will not work using a USB-to-parallel adapter.

I think the problems go back to the nature of how USB works-and if I recall correctly, it is that a USB device does not send the data through steadily, but rather in packets or bursts, and it may wait to fill the packet before it sends it. That's just from memory so don't quote me on it...

And it's never a waste of time to try(unless you don't have the time to spare)-you're sure to learn something whether it works or not.

Remember, Mach was written in the first place after Art was told it was impossible....

______________________________________
Andy Wander

-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Danny Miller
Sent: Thursday, October 23, 2008 7:02 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Mach3 & laptops

Ha actually I do have a old machine... which I snagged off the curb at
heavy trash day. For this reason. BIOS shows a 4GB hard drive and
pretty old AMD processor. I would have liked to avoid trying to get it
working and all but it is an option. Might be a good idea to keep the
laptop out of the garage anyways. Does it run ok on old-ass systems?
I'd probably put a fresh install of XP on it, a wireless networking
card, and nothing else to clutter it.

Well on the USB-to-serial cables, those use a virtual port driver that
makes a new COM port show up. Any program can use it just like any
other COM port they don't know the difference. I assume a
USB-to-parallel cable would work the same way but I certainly wouldn't
be surprised if Mach3 had a problem working through the virtual port
driver and physically being bridged through different hardware.

On the other hand, I can say this- my laptop had mega problems running
through the built-in serial port at high speeds. Started dropping
characters, probably just overran some lousy slow part of the
southbridge design. Well, when I switched to the USB-to-serial and ran
the serial data through that, all those problems went away. So, it's
sort of "plausible" that a USB-to-"X" cable could perform better if the
motherboard had problems. I'm skeptical though. Andy Wander says "no
way" so it may be a waste of time to try.

Danny

David Speck wrote:

>
> Danny,
>
> The problem is not with accessing the parallel port, but with the
> internal timing of the Mach3 program.
>
> Mach3 uses a special kernel mode software driver which is necessary to
> provide high precision timing required to get all the various step
> pulses out the door at the precise instant needed for a proper cut.
> Laptops have all sorts of integral proprietary hardware with special
> drivers that confuse the dickens out of Mach3.
>
> When you get down to it, it's pretty amazing that Mach3 works as well as
> it does, considering that even on a desktop, Windows is a highly
> non-deterministic operating system. It takes a lot of high power
> programming on Mach3's behalf to make sure Windows does not decide that
> NOW is the time it has to do a defrag, just as you are half way through
> the 4167th line of your G-code program. Laptops just add a whole
> 'nother layer of complexity to the issue.
>
> Since Mach3 will run just fine on an old Pentium 3 that you can snag for
> free at curbside on trash day, it's just not worth the developers'
> effort that would be required to make it compatible with laptops,
> particularly when nearly every laptop is a collection of custom parts.
> (Have you ever tried to buy a replacement keyboard or LCD for a laptop?
> -- essentially every model is unique, and the corresponding internal
> software drivers are similarly unique).
>
> I'm pretty sure that Mach3 directly writes to the parallel port I/O
> pins, and will not work on a USB to Parallel adapter, at least not in
> the versions that I was familiar with.
>
> HTH,
>
> Dave
>

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