ELAUSYS JA-KNX gateway

The ELAUSYS JA-KNX gateway enables communication between Jablotron 100 alarm systems and KNX installations. KNX is the standard for wired home automation and building automation. It is used in many (office) buildings, large complexes but also in homes, and is known for its high reliability.
By connecting Jablotron 100 to KNX, the KNX installation gains access to all available information. Conversely, it can also activate the alarm system or switch Jablotron outputs. This offers interesting possibilities. Jablotron sensors on windows can then be used to switch air conditioning or heating (off) when windows are open.

Alternatives

There are alternatives to realize such a connection. Jablotron can also be integrated into Home Assistant (HA) and HA can in turn easily exchange information with KNX.
I considered that, but ultimately did not do it. Such an alternative is, as it were, a configurable gateway – man in the middle – where the Jablotron and KNX side must always be maintained. In addition, Jablotron and KNX have proven reliability, where HA does not yet have such a track record.

Hardware installation

ELAUSYS promises seamless integration, and for the software that is completely true. However, for the hardware it is different. The interface does not have direct access to the Jablotron bus and therefore an intermediate step is followed; The KNX interface communicates to RS485 and is then connected to the Jablotron 100 using the JA-121T (RS485 interface). This means that you always need a JA-121T - for which I had no other application - which approximately doubles the required investment. Fortunately, the connection between the ELAUSYS KNX interface and the JA-121T is easy to realize with four wires. No terminating resistors are required.
Because the interface is ultimately connected to the Jablotron bus, it offers the same flexibility as the connection of other bus components. The KNX interface does not have to be physically placed in the central unit, but ‘somewhere’ where the KNX and Jablotron buses are available. I had already taken the connection into account in the design and did place the interface in the central unit. The KNX connection is equipped as standard with the well-known Red/Black KNX connector.

Software installation

The software installation is very simple. In the Jablotron environment, only the JA-121T needs to be added to the device list. The gateway does not need to be configured further.
On the KNX side, the interface is immediately recognized in ETS – that is the KNX configuration software – and the configuration file can be retrieved online. The interface is now ready for use.

Device status

The interface can report the status of 96 devices such as PIR sensors or window contacts. Incidentally, devices are referred to as ‘Zone’ in the software. Each device is available within KNX as a group object with a switch status that can be ‘On’ or ‘Off’. Of course, these are only readable.
What is unfortunate is that the information is not available in real time. The central unit does not put such information on the bus itself, so the interface must always retrieve all the information cycle. Depending on the query round, it can take 3 to 20 seconds before the status is updated. That is fine for the status of an open window, but annoying if, for example, you want to switch on the lighting when a door is opened. This can be solved by sending the device status in Jablotron to a PG, the status of which is updated immediately.

PGs

The PG inputs/outputs of the Jablotron central unit can be read and written via two KNX group objects (switches). This works immediately with a small delay of about one second.
The number of PGs is limited to 32.

Alarm

Alarm zones can be switched on or off via KNX, and various types of alarms can be triggered. I don't use that (yet).

Experience

We have had the ELAUSYS Jablotron/KNX connection active for over half a year now. What is particularly striking is that the interface is not noticeable and simply does its job reliably. We use the interface for status messages and for controlling lighting. We have not had a single failure.