1-Wire - Sensors show 85°C above 53°C, how do I fix this on Windows XP?

Question

Hello,
I have a 1-wire sensor system connected in the attic to an old computer on xp. I measure through a soldered com port circuit with passive power supply.Unfortunately above 53C sensors show 85C below 53 show perfectly

what could be the cause? I have read about changing the transmission, but how? There are several descriptions for linux which I do not want to switch to....

Steryd3 · Answer

A bit strange- when I used this sensor in a microprocessor system (on an AVR) there was no such phenomenon. The transmission does not change - only the temperature values sent from the sensor change. The value 85 - from what I remember - is characteristic insofar as it is the result of the first measurement from the sensor - after the first power-up. If I were you, I would take a look at the sensor to see if there is any assembly error or mechanical damage which becomes apparent when it is heated up. Alternatively, try replacing the sensor - it costs a few PLN and can explain a lot.

Anonymous · Answer

I have also tried on the sensors ddicated for cookers and liquid measurements that I got for the pica (galmet) when connected to the cooker they work ok, when connected to the system 50 some and 85C. Other than that there are no problems even minus temperatures they read....
PS. galmet sensors have 2 wires so connecting the power supply is out, ordinary even connecting 1 under the whole bus gives the above mentioned error.
There was a description on the net about changing from 500ms to 250ms per sensor.... ok, lampomittari has this possibility, but also nothing. I also checked the speeds of the com port from the lowest to the highest....

Jacek Rutkowski · Answer

If you are using the full resolution of the DS18B20 sensors then the conversion time is 750ms and for at least this time a logical single should be sustained on the bus before you start reading.

Anonymous · Answer

Ok, but if in Logtemp there is no possibility of adjusting and there is only how long the reading should take. Should I lengthen the reading? Because I have tried up to 5 min and nothing. Or maybe the com port speed?

3-2-1-zwarcie · Answer

Try swapping the power supply from the parasitic to the normal one (i.e. connecting the sensor on 3 wires). I heard somewhere that the sensor may not be getting enough power through the parasitic.

Anonymous · Answer

It helped a little now I am looking for a lank controller

1-Wire - Sensors show 85°C above 53°C, how do I fix this on Windows XP?

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