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Common KNX Issues

Table of content

Check configuration detects issues

If the Check configuration function is showing errors, there are a few reasons listed below that are almost always the cause of the problem. Please double check if any of them applies to your configuration.

1. Missing Read (R) or Transmit (T) flags on STATUS objects

On each STATUS object (e.g. light On/Off STATUS) a Read (R) flag makes sure that the 1Home Server is allowed to read the value on the KNX device, while the Transmit (T) flag ensures that any changes made to the device are transmitted across the system and are thus also sent to your Matter app of choice and other systems running on your 1Home Server.

Solution: Set the Read (R) and Transmit (T) flags on your STATUS objects. Follow the guide for each supported KNX device type to learn which flags need to be set on which group objects.

2. KNX device is using KNX Secure

Does the problematic KNX device have a blue shield shown next to the group objects in the ETS as shown in the image below?

KNX Data Secure

This means that the KNX device is using KNX Secure which prevents 1Home Server from communicating with it.

Solution: If your KNX device is configured as a KNX Secure device, a workaround is required for the 1Home Server to be able to communicate with it. Fix the issues with KNX Secure.

3. A KNX Line Coupler is blocking the traffic

⚠️ Even if the line coupler is configured to pass all telegrams it is sometimes still blocking some of the traffic! We have seen this for example with the Schneider KNX Coupler (MTN6500-0101) device and some others.

Solution: To identify if a KNX Line Coupler is preventing 1Home Server from communicating with your KNX device, please connect the 1Home Server directly to the bus cable on which the KNX device in question is connected so that the Line Coupler is NOT between both devices. Disabling all filters or setting the settings to routing is sometimes not enough.

Once you have identified that line coupler is indeed blocking the traffic, you can now look into the correct configuration of the KNX Line Coupler.

4. Using a secondary KNX group address

If you are using a secondary group address (see the image below for an example) for your STATUS objects in 1Home Server, the 1Home Server will not be able to read the status of the device. This is due to the fact that only a primary group address can be read from the KNX.

Secondary Group Address

Solution: Use the primary address for your STATUS objects.

5. KNX BUS voltage problem

There are two possibilities for this:

  1. There are too many devices on the KNX line compared to the capacity of your KNX power supply. Make sure that your power supply has enough capacity (in mA) to cover all your KNX devices. You can see an estimated consumption of your KNX devices on each line in the ETS under the Devices view, under the Parameters section.
  2. We have seen a case, where an auxiliary power of a KNX device was connected directly to the KNX BUS and not to the auxiliary power cable. This made some devices unable to work correctly while others still worked well. Please make sure that the KNX bus cable is only used on the KNX bus ports.

6. Still facing issues?

If none of the above helped you solve the issue, follow the steps below:

  1. Connect to the KNX installation via your ETS5 or ETS6 using the 1Home Server built in KNX IP-interface.
  2. See if you can interact with your KNX device (try reading and writing it). If this works but you still have issues with the device in 1Home Server, double check that the correct group addresses are used. Otherwise reach out to our support for further diagnosis.
  3. If you are unable to interact with the KNX device, there is something filtering the communication between it and the 1Home Server. Please check again the above issues regarding the KNX Line Coupler and KNX Data Secure.
  4. If this still didn't help you identify the issue and you have another KNX IP interface at hand, repeat the above steps using this second KNX IP interface. If this one works, then reach out to our support. If it also doesn't work, then the issue lies somewhere in your KNX configuration.
  5. If nothing of the above worked, please submit a 1Home Server Bug Report..