Is there a way to set the cache delay? There is the case where you don't want sensors read every second (for power consumption, load, or other reasons), but want values instantly. Setting the cache delay would address this, and the shell script could read this value and adjust accordingly. Also, is the time of the cache reading available? The above are issues also solved with the database approach.
C > On Sep 23, 2015, at 10:35 AM, Jan Kandziora <j...@gmx.de> wrote: > >> Am 23.09.2015 um 14:35 schrieb Alex R. Gibbs: >> >> We have dozens of DS18B20 temperature sensors at 3 telescopes. I'd like to >> poll >> them and cache the results so that other programs can retrieve the latest >> temperatures with less than 50ms delay. > So basically, you want the other programs to access the cache *only* and never > trigger a conversion themselves because that may take while. That's something > you > cannot enforce with owfs, you can only ensure it by taking additional > precautions. > > 1. Power all sensors. That's required because we want to use simultaneous > conversion > in the next step. Why do you want that? Because you wrote "dozens of sensors" > and > conversion for dozens of sensors would take up dozens of seconds if you do > single > conversions. > > 2. Trigger a simultaneous temperature conversion every n seconds (with n being > smaller than the cache timeout for temperature). You do that by writing "1" to > /simultaneous/temperature. Use a simple script like this: > > > #!/bin/sh > while : ; do owwrite -s localhost:4304 /simultaneous/temperature/ 1 ; sleep 1 > ; done > > > Don't forget to wait a second so the first conversion result is ready. > > > 3. Read the cached values in the sensor directories as often as you like. > They should > never trigger a conversion by themselves because the script from step 2 has > already done > that. > > > Kind regards > > Jan > > ------------------------------------------------------------------------------ > Monitor Your Dynamic Infrastructure at Any Scale With Datadog! > Get real-time metrics from all of your servers, apps and tools > in one place. > SourceForge users - Click here to start your Free Trial of Datadog now! > http://pubads.g.doubleclick.net/gampad/clk?id=241902991&iu=/4140 > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers ------------------------------------------------------------------------------ Monitor Your Dynamic Infrastructure at Any Scale With Datadog! Get real-time metrics from all of your servers, apps and tools in one place. SourceForge users - Click here to start your Free Trial of Datadog now! http://pubads.g.doubleclick.net/gampad/clk?id=241902991&iu=/4140 _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
