How to read KNX group values form bOS server

PIotr Witkowski 2 years ago in Devices / KNX updated by Jürgen Jürgenson 2 years ago 9


Its it possibe to read group value from bOS server. :E.g: "GroupValueRead" sent from KNX network and then get response "GroupValueResponse" from bOS?

I tried to change "Read" flag to "TRUE" under Commuunication section but bOS is still not responding to "GroupValueRead"


On ETS, you need to be sure that the flag R is actually active on the group address you want to read, otherwise KNX won't give you the feedback on demand. If it doesn't you can force to activate the R flag (don't forget to download to the device).

On bOS side, you have the option "Read Value Cyclically" under the Status option.

When this option is active, you can set a cyclical reading delay (in minutes).

Don't know if this is what you're looking for.

Best regards

Thanks for answer Ricardo. It seems my question was missuderstood.

I want to do somethign exactly oposite. KNX device wants to read from bOS this value.

KNX device sent "GroupValueRead" over KNX/IP to bOS and then bOS server responds "GroupValueResponse" with actual value. E.g: after KNX device (panel display) reload it wants to read all actual values from bOS server.

Solution what you provided is exactly oposite. bOS server reads actual values from KNX network.


Does the register you are writing to from bOS have Write flags active then? 

It should work fine: Make a dummy register in ETS. For example temperature 2bytes 9,001. If it has write flags active it should see/update values that are coming from bOS.

Image 4301

Tested with jigsaw, worked fine for me.


The output and test what you did. Is it "GroupValueResponse" on previously received "GroupValueRead" or its just "cyclic sending of write" value?


It's not cyclically sending. It updates it's value if it has changed in bOS.

But if you want to read it from ETS/KNX you need to activate the read flag in bOS.

Image 4305

Point is that after enabling "read" flag the bOS it not responding to "read" message received from KNX network. Have you check such scneario in your test ?

1. Send "read" message (GroupValueRead) from KNX to bOS

2. Observe whether bOS responded with "reply" (GroupValueResponse) to KNX network

Yes it does respond. 

Image 4312

OK. Thanks to Comfortlick support problem solved. It tuned out:

  • If Conenction Type is "KNXNet/IP (Falcon) it dosent work
  • If Connection Type is "KNX IP" it does work <-  bOS responds to "GroupValueRead".

Not sure what are the differences between these two. Anyway thanks eveyone who was involed and spend some time to help me. Problem SOLVED.

Oh, good to know. Didn't even think about it. On my jigsaw the connection type was set to jigsaw so with it, it works too.