It starts procedure "convert" on all devices on the bus - hence it actually
only
for values volt* and temp*.
While read from simultaneous/volt value "1" (time of it is set by
cache-options)
procedure "convert" is not started at data reading from device/volt*. Here an
example of my script for the program similar rrdtool:
[ -f $Base/simultaneous/temperature ] && {
sim=`cat $Base/simultaneous/temperature`
if [ "$sim" = "0" ]; then
echo 1 >$Base/simultaneous/temperature
fi
}
val=`cat $Base/$dev/temperature`
It allows very quickly to obtain data from such quantity of gauges:
# ls -d /mnt/1wire/28.* | wc -l
77
#
:)
Rob Conway wrote:
> 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 -----
> *From:* Paul Alfille <mailto:[EMAIL PROTECTED]>
> *To:* [email protected]
> <mailto:[email protected]>
> *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]
> <mailto:[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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>
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