Interrupt jitter on Kuper Control RTMC48 Motion Control Card?

Interrupt jitter on Kuper Control RTMC48 Motion Control Card?

[Stefan Diercks]

Hi Group!

I am going to install dosbox on a linux system to use some old
proprietary control software that directly accesses an ISA-Card that
controls stepper motors.

Hardware: Pentium 233 or PentiumII 233 on ATX-Board with some
ISA-Slots and a  "Kuper Control RTMC48" Card (used for Motion Control
applications)
on http://www.kupercontrols.com/Kuper/Products/Kuper2001/K2001.html is
a picture of its successor. It is used to control stepper motors.

I assume it is very important, to have very little interrupt jitter
with dosbox direct hardware access. I haven't seen the card itself (it
was built into an old computer on a Film Production Set) but I have
seen the system up and running. I will figure out its IRQ and IOPORT
and use DOSBOX's Direct hardware access.

Of cause it depends on how the card manages Timers, and in what manner
Interrupts are used. Is there anyone out there who got anything
comparable running satisfactory? I expect interrupt jitter to cause
the stepper timings to run out of range. Should I use a faster
Computer to start with? :D Hmm, maybe I should, but the jitter
question is the same. What are your suggestions and experiences?

Stefan Diercks

Re: Interrupt jitter on Kuper Control RTMC48 Motion Control Card?

[Frank Cox]

On Mon, 30 Mar 2009 00:22:08 +0200
Stefan Diercks wrote:

> Of cause it depends on how the card manages Timers, and in what manner
> Interrupts are used. Is there anyone out there who got anything
> comparable running satisfactory? I expect interrupt jitter to cause
> the stepper timings to run out of range. Should I use a faster
> Computer to start with? :D Hmm, maybe I should, but the jitter
> question is the same. What are your suggestions and experiences?

Control stuff like that is something that I've never attempted with Dosemu.

However, since it sounds like you're planning to dedicate a computer to this
task, I'm thinking that you might save yourself considerable hassle if you
simply install Freedos (or something similar) on the computer and leave it at
that.  If the only job this thing does runs under DOS, then why fight city
hall, as it were.

-- 
MELVILLE THEATRE ~ Melville Sask ~ http://www.melvilletheatre.com

Re: Interrupt jitter on Kuper Control RTMC48 Motion Control Card?

[Stefan Diercks]

Frank Cox wrote:
> However, since it sounds like you're planning to dedicate a computer to this
> task, I'm thinking that you might save yourself considerable hassle if you
> simply install Freedos (or something similar) on the computer and leave it at
> that.  If the only job this thing does runs under DOS, then why fight city
> hall, as it were.

You are probably right, Frank. There are several issues to face for
this task. The Kuper software also makes use of parallel ports, also
some people report that not all mice work with it. The system is very
valuable for many today's tasks in motion control applications. First
I wanted to add network support to it, using Microsofts dos client for
windows networks, that worked very well a decade ago. Then I thought
it might be nice to have an up-to-date Multitasking OS in background -
and here I am.

Dosemu is a great piece of software, are there any reports about any
other special hardware people have used successfully with dosemu,
except for sound and network cards?

Stefan
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Re: Interrupt jitter on Kuper Control RTMC48 Motion Control Card?

[Paul Crawford (at UoD)]

We make use of dosemu for antenna control and use the IRQ-5 interrupt 
line along with the timer-0 interrupts for our own software.

Our main reason for keeping with DOS is simplicity - we don't need to 
change the working software or worry about device driver updates. 
However, we were keen to move from Windows 95 to LINUX/dosemu due to the 
great improvement in security (from none to good!) and networking.

We find the IRQ-5 hardware interrupt seems to get through pretty 
reliably, but the timer-0 stuff can go AWOL for over 0.25 seconds at 
times. We run dosemu with nice level -11 (to prioritise over the 
X-server) and disable any cron jobs that could take away host time 
significantly at regular intervals.

I don't know about the particular card you use, but the cases where we 
used stepper motors the hardware controlled the stepping, and only the 
reaching of set points or detecting of limit/reference positions relied 
on rapid response from the software.

Maybe not much help, but just to share our experience.

Regards,
Paul
-- 
Dr. Paul S. Crawford
Satellite Station
Dundee University
Small's Wynd, Dundee,
DD1 4HN, U.K.
Tel: +44 (0)1382 38 4687
The University of Dundee is a Scottish Registered Charity, No. SC015096