Will be answered

saving float variables on a iridium UMC C3 server

JBOY 1 year ago updated by Vladimir Ovchinnikov 6 months ago 3


I have some temperature readings on my KNX bus which i want to log in the database (to visualize and perhaps do some control) on my UMC3 iridium server.

The temp value is a 2-byte float (in KNX: type 9.001 temperature (°C)).

It is inside the server project defined as a 'float 16bit', subtype 'Temperature C'

Now, if i want to save this kind of feedback into the database, it seems i have three options:

-save as a signed 32 bit

-save as a float 64bit

-save as text

At first, i tried to save as a signed 32bit. This works at integer level of 1°.

At second, seeing the accuracy of 1° is rather high, i want to switch to 0.1° accuracy.

So i changed the option to save as float 64bit. This does not work, i don't get any update nor new points in the database of the values, while this data format is much more compatible

I played with the 'deadband value', putting it to 0 and 0.1, this does not work.

I still see the raw bus values (eg. 21.29999°C) correctly in the server interface, also updating seems to be correct here.

So my question: how can i save my temp value with an accuracy of 0.1°C in the database?

I would like to stick to °C and not go to a scale of 0.1°C.

Is there a correct conversion routine for all the datatypes in KNX towards the javascript float 64?



Will be answered


At the moment it does not work as intended. By "Deadband" parameter we will make a change and check its work with float.

Good day Vladimir,

have you a news for this issue?

I try with last firmware ( and studio and still deadband not work as intended.



The bug is still in operation, because its cause covers several other important functions. We'll let you know when we're ready. Thanks for understanding.