Re[2]: RT-Control questions

In a fast control system, what would be the way to go:

(1) Create a task with something like make_periodic_task
    and read an input value (port),compute output and
    write to the card. 
    Are data transfers to the DAQ board possible 
    without interrupts/dma transfers with ports/registers?

(2) Install an interrupt handler which uses e.g. the APIC timer instead.
(3) Install an interrupt handler which is triggered by some timer on
    the DAQ board itself. Is that possible? Faster, more reliable?
(4) Asynchron invokation of a control function is only suitable for
    pure data acquisation in kernel/user-space measurement applications, 
    not control.  Am I right?

Is it necessary to pass any further work to a task and exit the interrupt
handler as fast as possible?
Are there major drawbacks,side-effects when using interrupt handler?

In a control program I would only read one input value, do some
calculations and output it. So I would have read the newest data
available and somehow circumvent the fifo-buffer. How
can I accomplish this?


I could not find rt-linux based comedi examples in the archive:
https://cvs.comedi.org/cgi-bin/viewcvs.cgi/comedi_examples/comedi_example
s.tar.gz?tarball=1

Thank you very much for your answers so far :-)

Ciao,
 Dominic

Received on 2002-08-08Z16:54:34