This interests me greatly. So with my network below, i would have to poll
each alarm directory in turn. Indicated by <<<<<<<<<< ?
Thus on each ds2409 coupler if both branches are in use (ie contain ds1820s
on them) this would need each branch's alarm directory polled, from the ow
uncached directory.
This seems a shame as I would have thought a single top level directory with
each device in the alarm state contained within would have more merit, but
of course the ow Alarm Search command wouldn't find the other branches
unless the coupler is switched between branches?.
But then again couldn't the alarms all be grouped together by owfs into a
top level directory?...
*"If the measured temperature is lower than or equal to TL or higher than
TH, an alarm condition exists and an alarm flag is set inside the DS18S20.
This flag is updated after every temperature measurement; therefore, if the
alarm condition goes away, the flag will be turned off after the next
temperature conversion."*
..as surely this flag is picked up by owfs when it polls the ds1820s each
time? A new feature maybe? /var/1wire/current_alarms/*
At the moment this leads me to think the ds1820 alarm function (at least for
me) is not worth the effort as i can code a more responsive event monitor at
the software end, just by reading the cached values. Others may need
faster resolution or only need to see alarmed sensors (especially if they
have 10s/100s of sensors).
My current setup checks outdoor and greenhouse temp to determine whether to
turn on a 240VAC power switch to heat up (or cool down) the greenhouse.
owfs polls every 15 seconds? so this resolution is more than enough, when
my monitor polls every 15 minutes.
/var/1wire/
|-- Greenhouse_Hub
| |-- aux
| | |-- Soil_100mm
| | |-- Soil_300mm
| | `-- alarm <<<<<<<<<<<<<<<<<<<<<<
| `-- main
| `-- Rain-Wind
|-- Greenhouse_Hub2
| |-- aux
| `-- main
| `-- Solar_Humidity
|-- Greenhouse_Hub3
| |-- aux
| | |-- Greenhouse2
| | |-- Outdoor_Greenhouse
| | `-- alarm <<<<<<<<<<<<<<<<<<<<<<<<<<
| `-- main
| |-- Power_Switch
| `-- alarm <<<<<<<<<<<<<<<<<<<<<<<
|-- Office_Hub
| |-- aux
| | |-- Shed
| | `-- alarm <<<<<<<<<<<<<<<<<<<<<<<<<<
| `-- main
| |-- Conservatory
| |-- Kitchen
| |-- Office
| `-- alarm <<<<<<<<<<<<<<<<<<<<<<<
|-- Office_Hub2
| |-- aux
| `-- main
|-- Office_Hub3
| |-- aux
| `-- main
|-- Test_DS1820_S
| `-- errata
|-- USB_Dongle2
`-- alarm <<<<<<<<<<<<<<<<<<<<<<<<<
`-- Test_DS1820_S
`-- errata
Here you can see why one ds1820 is in alarm mode: Test_DS1820_S
$ cat /var/1wire/alarm/Test_DS1820_S/templow ; echo
70
$ cat /var/1wire/alarm/Test_DS1820_S/temphigh ; echo
75
$ cat /var/1wire/alarm/Test_DS1820_S/temperature ; echo
22.875
Nick.
http://kiwi-hacker.blogspot.com/
http://www.kiwi-hacker.net/weather/
On Sat, Mar 19, 2011 at 11:11 PM, Marc MERLIN <marc_n...@merlins.org> wrote:
> On Sat, Mar 19, 2011 at 11:59:59PM +0100, Vincent Danjean wrote:
> > > Got it, and I take it owfs automatically does 'alarmed only' searches
> on its
> > > own on 1sec interval or somesuch.
> >
> > No. owfs does nothing on its own. It does 'alarmed only' searches when
> you
> > ask it to list the contents of an alarm/ directory.
>
> Gotcha. So if I poll an alarm directory once a second, it will poll that
> bus, or hub sub-branch once a second.
> If I only have a single DS2408 to poll for I/O state though, it sounds like
> the bus traffic from my polling for alarm may not be much less than my
> polling the DS2408 directly.
> If I understand correctly, though, it will be faster to poll alarm for a
> bunch of DS2408 all at once, and then talk to the one that triggered an
> alarm if need be, but if you only havea a single one it may not be worth
> it.
>
> > If I understand correctly (I also have a hub), each DS2409 allows to have
> > two separate branches (main and aux) that can and must be scanned
> separately
> > from the global 1-wire network.
>
> Yes, that's correct.
>
> > If you want to enumerate devices on a subbranch, devices on other
> branches
> > will not be involved. But if you want to scan on all your devices, you
> will
> > have to do it on all DS2409 branches.
>
> That is also correct.
>
> Since my DS2408 is by itself on its own branch, it sounds like scanning
> that
> branch for alarm or scanning the DS2408 for I/O status will likely take
> about the same amount of time (or close to it).
>
> Thanks for the info,
> Marc
> --
> "A mouse is a device used to point at the xterm you want to type in" -
> A.S.R.
> Microsoft is to operating systems & security ....
> .... what McDonalds is to gourmet
> cooking
> Home page: http://marc.merlins.org/
>
>
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