# Fronius

> Sysmo

Source: https://voltmasters.io/en/docs/device-integrations/pv-inverters/fronius/

#### Enabling Modbus TCP (SunSpec) on Fronius Inverter

**1\. Access the inverter's local web interface**  
Connect to your local network and enter the inverter's IP address in your browser. This opens the Fronius web interface.

**2\. Go to Settings → Modbus**  
In the left-hand menu, click **MODBUS**.

**3\. Enable Modbus TCP data transfer**  
Under "Gegevensoverdracht via Modbus" (Data transfer via Modbus), select **tcp**.

**4\. Set the SunSpec Model Type**  
Under "Sunspec Model Type," select **int + SF** (integer + scale factor). This is the standard SunSpec register format most third-party EMS platforms, including ours, expect.

**5\. Verify the Modbus port**  
The default Modbus port is **502**. Leave this unless your network setup requires a different port.

**6\. Enable inverter control via Modbus**  
Make sure the checkbox **"Inverterbesturing via Modbus"** (Inverter control via Modbus) is checked. This allows the EMS to send control commands (curtailment, setpoints, etc.), not just read data.

**7\. Confirm and save**  
Click the checkmark (✓) icon top-right to save the settings.

![The Modbus page in the Fronius inverter settings, in Dutch, with data transfer over Modbus set to tcp and the Sunspec model type set to int plus SF.](https://voltmasters.io/assets/docs/image-1.webp)

**8\. Enable data logging during night hours**  
Go to **FRONIUS SOLAR.WEB** in the left menu, and under "Datalogging tijdens de nachturen" (Data logging during night hours), select **Ja** (Yes). This prevents the inverter from powering down its communication interface overnight, which would otherwise cause the EMS to lose connection during nighttime hours.

**9\. Save these settings too** with the ✓ icon.

![The Fronius Solar.web settings page, in Dutch, with datalogging during the night hours set to yes.](https://voltmasters.io/assets/docs/image.webp)