Hi Roberto, On 06/12/2012 09:21 PM, Roberto Spadim wrote:
> 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 This can also be accomplished with the DS18B20 -- you send the Skip ROM command followed by the Convert T command. It's called simultaneous temperature conversion. I have never used it but I understand that OWFS supports it (the DS18B20s must be powered for this to work). > 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 Yup, my understanding is that it exists and works. There is a "simultaneous" directory at the root of the OWFS, with elements inside it that I understand are to be used to make use of the "simultaneous temperature conversion" feature. Cheers, Eloy Paris.- > > 2012/6/12 Eloy Paris <[email protected] <mailto:[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.- > > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. > Discussions > will include endpoint security, mobile security and the latest in > malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Owfs-developers mailing list > [email protected] > <mailto:[email protected]> > https://lists.sourceforge.net/lists/listinfo/owfs-developers > > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
