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by Jiří {x2} Činčura

Calibrating Aeotec Multisensor 6’s temperature using OpenZWave (in Domoticz)

6 Nov 2017 2 mins Domoticz, OpenZWave, Z-Wave

The Multisensor 6 from Aeotec is a nice little device. I have three of these in my house at the moment (and I’m sure I’m not done yet 😉). Being data geek I always calibrate the temperature (and humidity) sensor to match my own “calibration” devices (ESP-8266 with Si-7021). The steps described in official documentation are correct, but because I use OpenZWave (in Domoticz) I had to do some specific steps to make it work.

It’s mostly related to negative values, because that’s where the values fall appart. Let’s take the example from documentation. Setting the offset to -2,5 °C. That’s 256 - 25. 231 in dec or E7 in hex. Thus, the final value is 0xE701 (for °C). This is 59137 in dec. Sadly, typing this as a configuration value was not working for me (with the current version of Domoticz). I had to put ‭-6399‬. That’s the same value, but converted to short (compared to ushort). You can get the value simply by subtracting 65536 from the value you computed (i.e. 59137). Also you can switch the calculator in Windows, in Programmer mode, to WORD size and you’ll get the same value in DEC row.

WORD value in calculator

More examples (all for °C):

  • -0.6-1535
  • -0.5-1279
  • -0.3-767

It took me a while to understand what’s going on, luckily OpenZWave is open-source, and adjust my values accordingly. Hope it saves you some time.

Note: Yes I know I can calibrate the temperature directly in Domoticz. I just like it done on device.

Profile Picture Jiří Činčura is .NET, C# and Firebird expert. He focuses on data and business layers, language constructs, parallelism, databases and performance. For almost two decades he contributes to open-source, i.e. FirebirdClient. He works as a senior software engineer for Microsoft. Frequent speaker and blogger at