Re: Linux vs. DOS

Matt

Thank you for your instruction sheet on setting up the rt patch and
installing EMC. With your help I now seem to have rtlinux running.

I seem to be having a problem with the EMC part though. I followed your
directions and when I execute run.64step378 I get a message "Permission
Denied". Also, if I try run.stepper I see on the command line emc start, but
then I get an error message that the stepper module file does not exist.
When I look under the plat directory I have the rtlinux, linux2.0.36, and if
I remember correctly the documentation directory, but they are all empty. Is
it possible that I got a bad .tgz file or are the files for these
directories in a separate download.

Appreciate all the help.

Tim
[Denver, CO]

> -----Original Message-----
> From: Matt Shaver [mailto:mshaver@...]
> Sent: Saturday, May 29, 1999 10:29 PM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Linux vs. DOS
>
>
> From: "Matt Shaver" <mshaver@...>
>
> > Andrew Werby wrote:
> >
> > [Oh. I really don't know anything about Linux, but it seems
> intimidating.
> > All the problems with "kernels", whatever they are, seem like they would
> > take over my life. I read some previous discussion here on the
> fine points
> > of running Linux , and I didn't understand thing one. Is there no
> > alternative? Does NT run in real time? Has anybody built a
> graphical user
> > interface for Linux that makes it more user-friendly? Is there
> a Linux for
> > Dummies?]
>
> 1. If you have the brains to contemplate retrofitting a
> servo controlled
> cnc mill, do machine work as a hobby, and subscribe to this
> newsgroup, then
> you have enough brains to deal with Linux. It looks really bad going into
> it, but once you get over the initial hump in the learning curve it's not
> bad at all. In fact Linux is becoming more and more popular all the time,
> so unless you're already retired, there's more than a small chance you're
> going to have some contact with it in the future if you work with
> or around
> computers for a living. There's no time like the present to get up to
> speed. By the way, DOS has a kernel too. It is found in two
> hidden files in
> the root directory of the boot disk called MSDOS.SYS and IO.SYS. There
> doesn't seem to be a /dos/src directory though... One difference between
> the two systems is that support for accessory hardware devices is handled
> in DOS by loading device drivers in the CONFIG.SYS file with a line
> such as DEVICE=C:\MYDEVICE.SYS. In Linux this support is provided by
> including the code in the kernel which means that the kernel is
> re-compiled
> to add support for new hardware. In truth, Linux also has loadable modules
> as well, but they are optional. Also, in Linux, there are directories full
> of files that perform the function of DOS's AUTOEXEC.BAT and CONFIG.SYS.
>
> 2. Linux is a much more reliable OS (doesn't lock up, get
> weird, or give
> you the "blue screen of death") than Win95/98 or NT and the only
> alternatives for a real time control application are systems like QNX and
> LynxOS which are specifically meant for real time control. They are
> expensive and there is a lot of debate (and I mean among guys with PhD
> behind their names) on the RTLinux mailing list about whether there is any
> real advantage to these systems over RTL.
>
> 3. All the inexpensive control programs that folks talk
> about on RCM and
> this list such as DanCAM, MaxNC, Stepster, etc. are only for use
> with stepper
> motor systems. This is to say that they output axis motion commands in the
> form of step and direction signals. You would be much better off to keep
> your existing servo motors, amps, and encoders due to their higher
> performance. This leaves alternatives like Lighthouse Software (big $),
> Delta-Tau (MEGA $), Bestsoft (no one can seem to get tech support), or a
> commercial control such as Centroid or Fanuc, or ... This is the gap that
> the EMC fills.
>
> 4. See my previous, very long post, for comments on NT and
> real time.
>
> 5. Caldera's latest version of OpenLinux has a graphical
> install and comes
> with a nice window manager called KDE (which I use on my Red Hat Linux
> system as well). You can download KDE from http://www.kde.org .The only
> problem is that the EMC doesn't run under the newer 2.2 version of the
> kernel yet, so you'll need to stick with Red Hat 5.2 (which uses
> the 2.0.36
> version of the kernel) for the moment. The installation isn't as
> bad as you
> think, and you'll reduce your problems a lot if you pick hardware from the
> compatibility list you can find at
> http://www.redhat.com/corp/support/hardware/intel/52/rh52-hardware
> -intel.htm
> l .
>
> 6. Yes, I think there is a Linux for Dummies book, but
> there is also a lot
> of documentation that comes with the boxed version of Red Hat Linux. There
> is a printed installation manual and many helpful files in /usr/doc once
> you get it up and running. In fact the online documentation on networking
> goes into some information on how Microsoft's networking scheme works, and
> this helped me solve some Win 95 problems I had been having! There is also
> the Linux Documentation Project at http://metalab.unc.edu/mdw/ .
>
> > [Would that be better than leaving the old relays in place?
> Also, can you
> > tell me why there's a strong smell of methyl mercaptans in the mill's
> > control box? If I didn't know better, I'd swear it was leaking natural
> > gas...]
>
> You'll need most, if not all of the existing electrical gear in your
> control to run thing like the spindle, coolant pumps, etc. The solid state
> relays that Jon refers to are simply an interface between the TTL level
> world of the computer and the coils of the power relays you are talking
> about which are probably actuated by 24 or 110 volt signals. You really
> need to understand how you present system works before you attempt to
> change it. Are their any schematics or other documentation like a
> maintenance manual that came with the machine, or which you could get?
> These will be INVALUABLE to you when you go to rewire things! I'll venture
> a guess that the smell is transformer varnish cooking.
>
> > [If you'd rather, we could take this off-list, but it seemed we
> were still
> > discussing things of general interest, so I'm replying in
> "public". The 8
> > axis Servo-to go card sounds interesting at $888 - it certainly beats
> > paying $1500 per axis. They mention running NT in conjunction with their
> > card, and something about how it (and DOS) can be induced not
> to interrupt-
> > do you know anything about this? They also talk about writing your own
> > algorithms, though- so I'm not sure how hard this would be. ]
>
> What they are talking about are real time extensions to NT
> written by Venturcom
> and other third party developers. I don't believe they have as
> good a level of
> performance as RTLinux, probably because the developers didn't
> have access to
> all the source code for the NT. In addition these extensions cost a lot of
> money for the developers kit, plus a per machine runtime license,
> in addition
> to the cost of NT itself. As for writing your own algorithms, if
> you can do
> that, well, let's just say you don't need any of my advice. I'm
> happy to see
> this discussion stay on the list as I think there is a subset of
> subscribers
> who is interested in this sort of thing. As I've said before, if
> you need any
> help in getting the EMC up and running, don't hesitate to call or write.
>
> Matt Shaver
> (410) 521-3715
> mshaver@...
>
>
>
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