Thank you for your answers!
The problem with selective search is that I don't know if the device is
still on a bus or not, so polling on ordinary search is more reliable for
hardware failure detection. Second, alarm is set for sensed values, not for
latches, so it is possible to miss some very short event.
I know, 1-wire is not the fastest network on the Earth, but I'm trying my
best :)
PS.
It seems it is not possible to set negative alarm values for DS18B20
temperature sensors. Or it is a bug in owhttp interface?
Best Regards,
Ivan, PhD
On Tue, Mar 27, 2012 at 12:13 AM, Serg Oskin <[email protected]> wrote:
> Try to use the alarm-directory.
>
> # Setup
> foreach 12.*
> openeach
> writevalue_to_set_alarm
> closeeach
> end foreach
>
> # Main loop
> foreach uncached/alarm
> openeach
> readvalue
> reset_alarm
> closeeach
> end loop
>
> --
> Serg.
>
> > Greetings to all,
> >
> > I am implementing a system which need to poll sensors (mainly DS2406 and
> DS2408) nearly every second. Of course I use uncached values of sensors to
> get the most recent data. I have about 15-20 sensors to poll.
> >
> > I see three options:
> >
> > First:
> > loop:
> > openfile("12.XXXXXXXX/latch.A");
> > readvalue;
> > closefile;
> > end loop.
> >
> > The most obvious one, but open/close file is rather costly operation.
> >
> > Second:
> > openfile("12.XXXXXXXX/latch.A");
> > loop:
> > readvalue;
> > goto_first_line;
> > end loop;
> > closefile;
> >
> > This is better, but is there some chance, that value will be cached
> somewhere inside OS?
> >
> > Third:
> > give up on owfs and use owhttpd and make tcp connections to read files.
> >
> > I think this is a heaviest one, but crossplatform, so can be used on
> windows. Can owhttpd have about 20 concurrent connections in a second?
> >
> >
> > What strategy to choose? Thank you for any help in advance.
> >
> >
> > Best Regards,
> >
> > Ivan, PhD
> >
> >
> >
> >
> >
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