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Serg & Paul,
I use powered devices so I have updated my script
to set simultaneous/voltage and temp to 1 then read all device data out
of cached data. crontab was also starting a rrdtool trend script at
the same time as my 1wire read script. It seemed to work OK however I put
a sleep in my rrdtool script such that my 1wire script can complete
first.
Question: does setting "simultaneous/volt
& temp" to 1 initiate a reading of just the volts (I assume Volts.all
& volt.x) and temp parameters or all data from the devices.
cheers
----- Original Message -----
Sent: Monday, November 06, 2006 3:00
AM
Subject: Re: [Owfs-developers] Fwd: [owfs
- Help] DS2450 and the NSLU2 (SLUG)
On 11/5/06, Serg
Oskin <[EMAIL PROTECTED]>
wrote:
Rob
Conway wrote:
> In an attempt to optimise the 1wire communications can
you comment on
> the following:
>
> *Reading data*
>
My current requirment is to read the volts every two minutes (although
> would like it faster especially when I get my weather station) from
all
> channels of 2 x DS2450 (A/D), temperature from 4 x DS18B20,
counter
> readings from 1 x DS2423 (counter) and read/write 4 x DS2406
(Switch).
>
> It is very convienient to use awk as I can do
some calcs as well, all in
> one line.
>
> My script
currently just uses individual awk lines for each
> "uncached/Volt.X"
parameter....
> Would it be better for the first line to get
uncached/Volt.All and
> subsequent lines to use
cached/Volt.All. I think awk will allow me to
> use $0,
$1,$2,$3 for each of the values in Volt.All. I "assume" the
> first line /"uncached/Volt.X"/ would cause a direct read from the
device
> and the three subsequent reads to /"cached/Volt.X" /would
simply get the
> last scanned data from cache and not cause additional
traffic. Is this
> correct and a better utilisation of
owfs.
Before data reading from DS2450 execute a command:
echo
1 > simultaneous/voltage
and then read cached data.
Serg is correct. The fastest method, especially if you have "power"
(rather than parasytically powered) devices is the initiate all the
temperatuer and voltage conversions, then read the cached results.
As
an anternative, especially if unpowered, there is a benefit to reading
uncached/volts.ALL, and parsing the result in your script. The time required
is 1 fourth of the individual readings.
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