Fronius KNX Gateway

Read a Fronius inverter from KNX

The INV-KNX-FR puts a Fronius inverter on the KNX bus through the local network. Production, grid exchange, battery state and string data become ordinary KNX group objects in ETS, refreshed every 1 to 255 minutes — for a HyperVisu dashboard, a KNX energy manager or plain logic that switches loads when the sun is out. It connects over the inverter's Ethernet port (Modbus TCP, port 502, SunSpec int+SF).

What it does

Publish production on the bus. AC power, daily and total energy, voltage and current per phase, frequency, power factor and inverter temperature — each as a typed KNX object.

Show each PV string. Voltage and current for 2 strings — spot a shaded or faulty string from the visualisation.

Follow the battery. Running status (charging, discharging, full, holding…) and SOC on the bus.

Know the grid balance. The Fronius Smart Meter delivers grid import or export as one signed object — set its Modbus ID (200 or 240) in ETS.

Act on it without a server. 64 logic functions in the gateway: gates with 8 inputs, 4-step sequences, weekly calendar triggers and maths — e.g. "surplus above 2 kW for 5 min → switch the water heater".

What it spares you

• No Fronius cloud API, no account, no internet dependency: the gateway reads the inverter on the local network.
• No PC, software bridge or visualisation server between the inverter and the bus.
• No new ETS application to learn: all Elausys inverter gateways share one application; only the inverter model differs.
• No separate 12 V rail: any 12–30 VDC supply, such as the Elausys PSA-15W.

Scenarios

• The Fronius inverter exports more than 2 kW: the gateway's logic switches the water heater through an Elausys SAE-816 channel.

• Surplus at noon: the EV charger enable and the pool pump start from KNX; both stop when a cloud passes for more than 10 minutes.

• Battery SOC above 90 % in the afternoon: the KNX heating switches to comfort setpoint to store heat in the slab.

• HyperVisu shows production, consumption and grid exchange next to the lighting and heating of the house.

• A KNX push-button LED turns green while the house is exporting.

Technical proof

• Inverter side: Fronius Gen24 (model 3) and Symo Hybrid / Symo / Primo with Datamanager (model 6); the SunSpec Modbus TCP interface over Ethernet RJ45
• Inverter setting: Modbus TCP enabled (Datamanager or Gen24 web interface), port 502, SunSpec model type int+SF, Unit ID 1
• ETS parameter: inverter model 3 (Gen24) or 6 (Symo Hybrid / Datamanager); Smart Meter ID in Device Options
• KNX side: refresh rate 1–255 min; single- or three-phase network selectable in ETS
• Logic: 64 functions — logic gates (8 inputs), 4-step sequences, triggers with weekly calendar, math operations
• Power: 12–30 VDC external on screw terminal; KNX bus < 16 mA @ 29 VDC; galvanic isolation between Ethernet and bus
• Housing: 2 SU (35 mm) for 35 mm DIN rail; +5 to +45 °C
• KNX connection: pluggable micro terminal, push-wire 0.6–0.8 mm solid conductor
• Network settings on the embedded web page (default IP 192.168.1.51); firmware update from the same page
• Configuration: ETS5 / ETS6

KNX group objects

Local, standard, independent

Every value is a standard KNX group object in ETS — nothing hidden in a proprietary app. The gateway polls the inverter on the local network; no internet connection, account or subscription is involved. The Fronius monitoring portal keeps working alongside.

FAQ

Which Fronius inverters? Gen24 and Gen24 Plus, Symo, Symo Hybrid and Primo — with Modbus TCP enabled in the inverter or Datamanager web interface.

Does it read the Fronius Smart Meter? Yes. Enable the Powermeter option in ETS and enter the meter's Modbus ID (usually 200 or 240).

Which SunSpec setting? Model type int+SF, port 502.

Does it work with HyperVisu? Yes. The objects are standard KNX objects; HyperVisu reads and charts them like any other.

More information

• KNX gateways for solar inverters — range overview
• Documentation and ETS application

• Inverters: Fronius Gen24, Symo, Symo Hybrid, Primo (SunSpec Modbus)
• Protocol: the SunSpec Modbus TCP interface, Ethernet RJ45
• Data: AC power, energy, voltage, current, frequency, PF, temperature
• PV strings: 1–2 strings
• Battery: 1 battery — status, SOC
• Power meter: Fronius Smart Meter (Modbus ID 200/240 set in ETS)
• Refresh rate: 1–255 min
• Logic functions: 64
• Power supply: 12–30 VDC external, screw terminal
• KNX bus current: < 16 mA @ 29 VDC, galvanic isolation
• Operating temperature: +5 to +45 °C
• Housing: 2 SU, 35 mm DIN rail
• Configuration: ETS5 / ETS6