KNX Connector


The KNX connector is part of the KnxExt and it implements connector support for the KNX protocol. It follows the standard connector model:

  • Connectors: used to configure a JKNXC connection to a KNX access point (typically an IP interface)

  • Functions: provide access to read/write/learn from within your Axon scripts

Current support

Currently KnxExt supports the KNXNet/IP version of the KNX protocol. Reading and writing is supported via tunneling.

It doesn’t support password protected projects. The password would have to be removed in order to be able to use it in FIN.

Importing an ETS project (*.knxproj)

The startup point to any KNX configuration is defining the KNX topology of one or several installations using the ETS tool, which can be downloaded from the KNX Association website ( ).

Here’s a sample project opened in ETS, showing the network topology, group addresses and the diagnostics/monitoring views:

After creating and configuring a KNX project, a *.knxproj file will be available and can be imported into FIN.

To upload a *.knxproj file into a FIN project, go to FIN System Integrator Apps -> DB Builder -> Connectors -> Knx -> Projects, click on the Upload button and select a *knxproj file.

In the same view, there are options to Replace or Delete the uploaded *knxproj file. When uploading a *knxproj file into a FIN project, that file is available for all Knx connectors created under that FIN project.

Creating a KNX connector

The mandatory requirement to create a KnxConn is the connector Uri. Additionally you can opt to provide a *knxproj file or not.


The connector URI has the following format:



  • IP – the IP address of the KNX interface/gateway device we use to access the KNX network

  • port - default for KNX is 3671


You can test out your connector using the connector UI under the Equip Tree accessible from the DB Builder app.

If trying to establish connection to an endpoint using NAT (Network Address Translation), add the knxUseNat marker tag to the connector record. NAT usage without extra safety measures is not recommended. Port forwarding provides universal access to a local IP network and KNX system. Any Internet user can discover the open port on a static public IP address and can, for example, access the KNX network via ETS. It is recommended to connect to the endpoint via VPN and to change the default KNX port (3671) to one from the unreserved range (50000-60000).

Learning data points from an imported *.knxproj

From the KnxConn view, discover the data points from the chosen *knxproj. Before learning a data point as a point in FIN, you have the ability to first edit its definition in the knxproj file by using the Edit Datapoint button in the point discovery interface.

This can be used for datapoints that don’t originally come with a data point type assigned from the knxproj, to configure if they are readable and/or writable or if need to change some of the point information before adding it to the equip.

Once done, select the points to add into the Equip Tree by clicking Add/Add all or drag and drop the point(s) under an equip.



When editing a data point the changes are made on the imported knxproj file, therefore all other KnxConns using that *knxproj file will be impacted.

Translating KNX DPTs into Haystack types

The KNX standard comes with a complex system of data point typing, which the *.knxproj parser inside the knx.pod translates into the FIN/Haystack data types.

Specifying the DPT

You can specify the data point type in the following formats. Refer to the KNX specification available at

  • 1.009 (close/open encoding)

  • DPST-1-9 (close/open encoding)

  • DPT-1 (generic boolean, no subtype)

  • DPST-4-1[0] (retrieves the increase/decrease encoding bit of the generic DPST-4-1 data point type, which is an 8-bit encoding)

  • 4 or 4-xxx (generic DPST-4-xxx type)

  • 4.001 (DPT subtype)

  • 4.009.0 (first part of the DPST-4-9 DPT)


Units translation from KNX to Haystack is done via the units.props file found under /etc/sys/. In case your *.knxproj file defines a non-standard KNX unit, you can add it to the units.props file or change an already existing binding in that file. A FIN restart is required after altering this file.

Custom units

There are some KNX projects that have custom units that are not available or part of our default KNX units list, these custom units can be added through the Unit Bindings window. There could be units that are named differently than the norm, which would also need to be added as a custom unit.

To get to the Unit Bindings window, expand the Knx tree under Connectors.

In the Unit Bindings window on the right, the user will find the below options:

  • Add - This will allow the user to add new custom units.

  • Edit - This will allow the user to edit any existing custom unit that was added.

  • Delete - This will allow the user to delete any existing custom unit that was added.

  • Import - This will allow the user to import a knx custom units list (.props file) into a project.

  • Export - This will allow the user to export a copy of their custom units.

  • Show Default - This will show the user a list of all default KNX units. Any unit without the check mark in the Default column means it is a custom one.


When adding a new custom unit, the user will select the Add button.

The user will be presented with the below fields:

  • Key - this is where the user will type in the custom unit found in the knxproj that doesn’t exist in our KNX unit library.

  • Existing Unit - this option allows the user to pick from existing units found in our KNX unit library that would match their custom unit name represents. For example, if the knxproj has a unit defined as “kwh” instead of the standard “kWh”, which is found in our default KNX unit library (found in the “Show defaults” button), the user can use this option to map their “kwh” unit to the “kWh” standard unit.

  • Custom Unit - this option allows the user to add a custom unit that is not found in our default KNX unit library so that it can be read properly.

Existing Unit

If the user selects to add an existing unit, then they can select the quantity and symbol for the new unit to add.

Key = the unit name in the knxproj.

Custom Unit

If the user selects to add a custom unit, then they can select the name, quantity, scale and offset for the new custom unit to add.

Key = the unit name in the knxproj.

Names = Provide a name of the custom unit. It should be a descriptive summary of the unit using words separated by underbar such as "miles_per_hour". Multiple can be added and separated by comma.

Reading and Writing

Reading and writing the same objects on KNX can be performed on the same group address or on dedicated group addresses independently. For example, reading a batch of switches/binary outputs is done with the 1/1/* group addresses, while writing to these channels is performed with the 1/0/* group addresses, or they both reading and writing can be performed on the same group address.


There is a KNX tag called knxThrottle that can be used to control the frequency of the data reads. This tag is applied on the connector record.

knxThrottle (number - duration) - If not present, it falls back to 100m/s. Value of 0 is acceptable which removes the throttle.