On 12/06/2016 11:04 AM, Sven Giermann wrote:
I have no idea of what pyownet does or how it is implemented...
But I know from another project, that DS1820 reports 85.0 deg C when
it encounters errors. Unfortunately without any other error flag!
That's why I implemented a way to accept a temperature of 85.0 only,
if the previously read temp was in that range (82-88), otherwise I
just skip this reading and try once again.
yes, it is good to have this kind of sanity check. But of course there
is the possibly left, that you encounter an error while you are in the
intervall of 82 to 88.
In this case one could read 85 repeatedly and must eventually ask if
there is an error...
Important sensor I did double up physically in my system. Hey, those
things are cheaper than writing a lot of lines of code ;-)
Maybe pyownet knows of this behaviour (it's by design and described in
DS1820 datasheet) and therefore throws an error, when it reads exactly
85 deg C?!
I am most definatly sure that pyownet does do this. Especially since the
author of pyownet Stefano Miccoli already answered to this problem
yesterday, and he did not mention anything of the like...
Regarding the error report of a sensor:
I checked now again the data sheet of the DS18*B*20 and this sensor does
NOT report an error with 85 degC. However, like Jan already stated
before it says:
/*The power-on reset value of the temperature register is +85°C./
And there is the problem. The new node latesttemp should fix the
problem, but somehow I am experiencing problems...
Thank You for Your thoughts
Martin
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