i don´t know if this exists but... in advantech and others rs485 modules,
exists a sincronous read mode, where you send a command to all slaves and
they save the value into the memory
after a time you can get all slave values
for example in a ds18b20 you will need 1 second to convert temperature
well... 1 second converting temperature in a network with 100 ds18b20 still
1 second... the time you will spent later is getting 100 values from
memory, this is faster than get 1 temperature from each ds18b20 (100
seconds at least)
i think it´s called sincronous ou parallel i didn´t tested it in owfs but i
think it exists, must confirm with guys here
2012/6/12 Eloy Paris <[email protected]>
> Hi Phil,
>
> On 06/12/2012 08:36 PM, Phil White wrote:
>
> > Hi All,
> >
> > This may, or may not, be applicable to this list. However, I am hoping
> > that someone here knows enough about MicroLAN to be able to clarify
> > something for me.
> >
> > Up to know, all my sensors have been polled. Simplistically speaking,
> > the PC asks "What is the temperature now?"
> >
> > What I am pondering is the ability for a sensor to suddenly, without
> > any warning, say "Gosh! It's hot here".
> >
> > Now, some of the iButtons come with a feature called a Presence Pulse
> > - although I am also interested in getting events via a DS2408 switch,
> > and the DS18B20 comes with an alarm function.
> >
> > Questions:
> > Is this possible (preferable, but not necessarily, with OWFS) without
> > polling the chip all the time?
> > what are my options?
>
> The 1-Wire protocol does not allow for slave-initiated communications;
> everything is initiated by the master.
>
> All 1-Wire devices have this "presence pulse" feature that you mention
> -- that's a fundamental part of the protocol, and all slave devices need
> to generate a presence pulse right after they detect a reset pulse
> generated by the master.
>
> I think the closest option to a non-polling solution is to use the alarm
> function that some 1-Wire devices offer -- it still requires polling but
> it can minimize it since only devices in an alarmed state would be
> contacted. The way the alarm function works is that only devices that
> are in an alarmed state will respond to a conditional search, so then
> you would only read the sensors that show up in a conditional search.
>
> Cheers,
>
> Eloy Paris.-
>
>
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--
Roberto Spadim
Spadim Technology / SPAEmpresarial
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