Am 08.10.2008 um 06:59 schrieb Hendrik van Rooyen:
"Blubaugh, David A." <dblub....elcan.com> wrote:
I have done some additional research into the possibility of
utilizing
Python for hard real time development. I have seen on various
websites
where this has been discussed before on the internet. However, I was
wondering as to how successful anyone has truly been in developing a
program project either in windows or in Linux that was or extremely
close to real time constraints? For example is it possible to
develop a
python program that can address an interrupt or execute an operation
within 70 Hz or less?? Are there any additional considerations that I
should investigate first regarding this matter??
[...]
If I run it between 2 PC's, faking the I/O by writing to a disk,
I sometimes get up to 250 such "pings" per second. Going full
duplex would pass a lot more info, but you lose the stimulus-
response nature, which is kind of nice to have in a control
environment.
Its not real time, but its not exactly yesterday's stuff either.
OK, this is gives an impression of SPEED.
We have also used python to do the HMI for an Injection
Moulding machine, talking to a custom controller with
an 8031 and an ARM on it via an RS-422 link running at
115200 - and the python keeps the link fully occupied
In your application the REAL-TIME requirements
are isolated and implemented in the custom controller.
And the HMI which has to be fast enough (SPEED, not HARD-REAL-TIME)
you implemented in python probably on a standard hardware/OS.
That is exactly what I suggested the OP to consider.
So don't be afraid - go for it!
Unless we do not know more details of the requirements
for the OPs application I think it is a bit early
to give this advice, althoug Python is a great
programming language in many aspects.
The only requirements we know of the OPs program project are:
- able to address interrupts (python can)
- execute an operation within 70[Hz] or less (python can)
But we do not know what operation has to be done at this
rate.
My concern is to point out, that the terms
SPEED and REAL-TIME and HARD-REAL-TIME
should not be misused or misunderstood.
Read:
http://en.wikipedia.org/wiki/Real-time
Grüessli
--
Kurt Müller, [EMAIL PROTECTED]
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