Re: [Owfs-developers] Simultaneous not working

[Mick S. <mi...@su...>]

Well this gets more curious.  I am now measuring the time for each read, 
reading type, power and latesttemp.  Time for all is generally < 0.1 
seconds, but then when I hit the slow loop the read for type is around 
0.7 seconds, the others still < 0.1 seconds.  I don't really need type 
so I removed it and re-tested, on slow loops the power read is around 
0.7 seconds, latesttemp still < 0.1 seconds.  So I removed power as 
well, just reading latesttemp, on slow loops that is now around 0.7 
seconds.  So it seems that at some point a sensor takes many times 
longer for its next read, irrespective of which field is read.

I have now tested with 19, 11 and 2 sensors and the slow loop occurs 
every 120 seconds.  I am intrigued to know what causes this, any ideas?

Thanks

Mick

On 06/08/2020 10:23, Mick Sulley wrote:
>
> OK I will log read times and see what that shows.
>
> You say 'I also log if the error of the 1wire bus changes.' how do you 
> do that?
>
> No I don't really need to read that fast, this is just a test setup to 
> get a better understanding so I can hopefully fine tune my main system.
>
> There should not be anything else running.  I just tried running top 
> at the same time, I monitored it at the point of the slow scan and 
> didn't see anything else significant.
>
> Mick
>
> On 06/08/2020 09:06, Martin Patzak wrote:
>> It looks like your timing has improved after all!
>>
>> in your original Python-code you could time every read for each sensor.
>> I have also powered sensors and a read is usually faster than 0.1 
>> seconds.
>> I log in a file if the read took longer than 0.3 seconds, which is 
>> almost never the case.
>> I also log in the file if the whole reading loop took longer than 3 
>> seconds, which again is almost never the case.
>>
>> I also log if the error of the 1wire bus changes.
>>
>> I read 25 sensors every full and every half minute, so maybe you 
>> could implement a delay as well and see if things get more consistent.
>> Do you need to read so fast in a loop for you application?
>>
>> What else is running on your machine? You could run top in parallel 
>> to your python loop.
>>
>>
>
>
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