On 05/10/15 15:54, Jan Kandziora wrote: > Am 05.10.2015 um 14:23 schrieb Alex R. Gibbs: >> However, other clients will have to wait if they happen >> to query owserver during the conversion/read. >> > No. That can only happen if you use parasite powered sensors. Because > parasite power occupies the bus during temperature conversion for > powering. That's a limitation of the hardware, you cannot do anything > about that. > > > With powered sensors, a client will only have to wait > > * if the particular sensor value is marked invalid, that is because > conversion on that sensor was never triggered or the last result was > already read out > > * if the particular sensor is currently at conversion stage and you are > reading uncached. > > > If you take the three precautions - powered sensors only; continously > trigger conversions within half the cache timeout, preferably > simultaneous ones; read cached values only - clients will never stall. > > One note here: some extra delay would actually be present. The simultaneous convert will execute the time-consuming conversion in the "background", true, but it will *not* read the actual results from each device in the background, afaik. On the next temperature read (i.e. when cache has expired), there *will* be bus traffic to actually read out the scratchpad (the results of the convert). Normally this is a very quick operation, but a bus operation DOES take place. If you are reading a lot of sensors, or something is blocking the bus, you will notice that this takes a bit longer than just reading a value which was cached in owfs. In most situations this isn't relevant though.
(I'm almost sure of this, and I cannot find any evidence of read operations executed in ow_simultanous. But please correct me if I'm wrong) Regards Johan ------------------------------------------------------------------------------ _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
