Dallas DS18B20 - Values 5 degrees to low ?

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kr0815
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Dallas DS18B20 - Values 5 degrees to low ?

#1 Post by kr0815 » 18 Nov 2015, 18:47

I have a test Setup with 2 x DS18B20, but they show wrong temperature
- value is about 10% of real value, so i had to multiply it by 10 with "%value%*10"
- now they are still about 5 degrees to high, i don´t have 26 degrees in my room.

I found some opics in other arduino Forums, People were also talking about exactly These 5 degrees, but i didn´t find a real answer

The DS18B20 are leftovers from other Projects, i never had such Problems before
I also swapped one of the 2 to another one, that was laying around and should be from another Batch - same results

What are your experiences ? Do you also have to multiply the values by 10 ?
I know the DS18B20 could be somehow "programmed", maybe that´s where the Problem starts ?

Best regards
Klaus

BertB
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#2 Post by BertB » 18 Nov 2015, 22:14

I have no problems at all.
Are you sure they are DS18B20?
The sensor are very precise

Backbone
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#3 Post by Backbone » 18 Nov 2015, 23:16

No problems here either.

Paco

kr0815
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#4 Post by kr0815 » 19 Nov 2015, 00:08

so for both of you, the Software Shows the right value, no Need to multiply by 10 ?
Oh, i looked in old Manuals, checked what i bought that time, could be they are 18S20 so S, no B ? Could that be the Problem ?

Backbone
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#5 Post by Backbone » 19 Nov 2015, 07:43

No need for correction or any multiplying.
All 6 sensors in use are spot on.
As far as I know the B or S version is only about the bit numbers.
https://www.maximintegrated.com/en/app- ... vp/id/4377
If you can use for this problem to be debugged an other Arduino code that can use the DS18 series and see if there is any difference in temp reading
http://iot-playground.com/2-uncategoris ... rduino-ide

This is what I use:
http://www.ebay.nl/itm/180970389726?_tr ... EBIDX%3AIT

Paco

DMeekelenkamp
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#6 Post by DMeekelenkamp » 19 Nov 2015, 13:00

Hello,

I used to have some problems with this sensor on a nodo
There 2 types of this sensor ds18b20 and the ds1820 the first sensor did work and the 2nd gave wrong values but if it was 5°C I don't know anymore.

I ordered both sensors at the same vendor but he randomly sold me the 2 types. So it was very confusing.

Greetings Dennis

kr0815
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#7 Post by kr0815 » 20 Nov 2015, 14:28

I found the Problem, it´s because im Using the S-Version isntead of the B-Version.
Even in the example ( https://github.com/esp8266/Arduino/blob ... rature.pde ) the Software Looks which Version is used, but in the code in --P004_Dallas.ino, i can´t find that Piece of code
Maybe in the next Versions ?

WilliButz
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Re: Dallas DS18B20 - Values 5 degrees to low ?

#8 Post by WilliButz » 24 Feb 2016, 14:48

Hi,

I played also with some Dallas 1820 sensors.

Wondered why I get strange numbers.
And yes I also have different type: 1820, 18B20

May be it is possible to add the 1820. The 18S20 is the replacement for 1820. Both have different calculation of the temperature.
The comparison to the 18B20:
https://www.maximintegrated.com/en/app- ... vp/id/4377

Here may be a good code:
https://github.com/milesburton/Arduino- ... ol-Library

Thank you!

WB

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