On Sun, 16 Oct 2016 09:47:26 -0700
Chris Albertson <albertson.ch...@gmail.com> wrote:

> On Sun, Oct 16, 2016 at 1:13 AM, Nicklas Karlsson <
> nicklas.karlsso...@gmail.com> wrote:
> > .
> > > The master board sends the latch command on the parallel
> > > port bus to other boards on the bus, as well as the
> > > computer.  The computer would have the luxury of responding
> > > before the next timer tick, nominally 1 ms.
> >
> Yes, this is how to do it but it requires two processors
>   1) a big machine like a PC (or ARM cortex-A) that runs most of LinuxCNC
>   2) A much smaller real-time processor that actually moves the signals
> between #1 and the machine tools

Execution of the Linuxcnc thread do not have to be accurate in the short time, 
arrival time of received packets could be averaged. For 100 receive times and 
full period jitter average would be within 1 percent of the computer clock 
triggering thread.

I have been thinking about running the real time part of linuxcnc on a cheap 
small computer without user interface and run user interface on ordinary 
computer. NML should already have support for this but I did not yet get time 
to try it. I am still working on the drivers. One reason for this is the cheap 
small computers available nowadays, it would also remove real time demands from 
the user interface computer and add possibility for "remote" control.

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