How to connect GARO GNM3D/T Series energy meter with Reduxi controller
Add your GARO GNM3D or GNM3T energy meter to the Reduxi Controller via Modbus RS485.
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Product photo of a light grey DIN-rail three-phase energy meter on a white background. Front: red 'GARO' logo at the top left, vertical text 'GNM3D-RS485' at the right, LCD with the unit 'kWh' (top row, value 0.01) and 'kW' (second row, value 0.0), red 'Touch' areas at the left and right edges, three touch buttons below the display with arrow symbols (up, enter, down). Label strip: 'YR 2017 338436A', 'CE M17 0120', '208-400VL-L 0.25-5(65)A, Class B 50Hz', '-25 C to 55 C', '1000imp/kWh', and a small LED at the lower right. Side label with terminal numbers 1 to 3, 11 to 13, N, 4 to 6, 7 to 12 and a wiring symbol. Screw terminals at the top and bottom.
1 Technical documentation
Find the instructions to connect and configure the meter on the manufacturer web page.
- GARO: GNM3D search – Link from the original article.
- GARO: Disc.ENERGYMETER 3P MODBUS RS485 (GNM3D) – Product page of the three-phase direct meter with Modbus RS485.
- GARO: GNM3D-RS485 manual (EN) – Manual with the RS485 connection and the meter communication settings.
- GARO: GNM3T-LP RS485 N manual (EN) – Manual of the CT-connected GNM3T variant.
- GARO: GNM3D and GNM3T Modbus protocol (EN) – Modbus RTU register tables and serial settings.
2 Required equipment
- Reduxi Controller
- GARO energy meter GNM3D or GNM3T with RS485 (Modbus) interface
- RS485 cable between the meter and the Reduxi Controller
- Laptop or tablet with internet access to configure the device in Reduxi
3 Meter communication settings
3.1 Default settings
The meter communicates over RS485 with Modbus RTU. The manufacturer protocol document lists these default settings:
| Parameter | Default value |
|---|---|
| Protocol | Modbus RTU over RS485 |
| Modbus address |
1 (range 1 to 247) |
| Baud rate |
9.6 kbps |
| Parity | None |
| Stop bits | 1 |
3.2 Set the Modbus address on the meter
Use this procedure only if the address, baud rate or parity on the meter differ from the values you need. The steps follow the GNM3D-RS485 manual and use the touch areas on the meter front:
9.6. Click left until PArIty appears and select no. Confirm the stop bit 1.4 Log in to the Reduxi web interface
You can open the Reduxi web interface in two ways:
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Screenshot of three Reduxi mobile app screens side by side, with cyan boxes and number badges 2 to 4. Left screen (dashboard, dark theme): menu icon at top left marked with a box and badge 2; 'reduxi' logo; tabs 'Real time data' (active) and 'Statistics'; price 5.79 € and temperature 3.2 °C; energy flow diagram with a house in the centre (-1.25 kW) and icons with values 69.0 W, 1.3 kW, 1.1 kW (red ring), -165.0 W with 97 % (red ring) and 0.0 W values at the bottom; tabs 'Power' and 'Energy'; bottom navigation: Dashboard, Diagnostics, Device control, Settings. Middle screen (side menu): 'reduxi' logo, 'Number of locations: 1233', heading 'Reduxi device management', entries '+ Add Reduxi location' and 'Reduxi devices' (marked with a box and badge 3), then 'My profile' and 'About app'. Right screen (device page): Back; picture of a black Reduxi controller with two Ethernet ports; status 'Connected'; card 'Update available': 'New update is available for your Reduxi device.' with button 'Download and install update'; card 'Connect to configurator': 'Tunnel connection enables remote access to your Reduxi configurator, without need to be connected to the same local network.' with button 'Activate tunnel connection' (marked with a box and badge 4); card 'Unit details' with field 'Unit ID'.
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Screenshot made of two parts side by side. Left part: Reduxi mobile app screen on a dark background. Top: Back button; picture of a black Reduxi controller with two Ethernet ports and a terminal block; status 'Connected' with a Wi-Fi icon. Card 'Update available': 'New update is available for your Reduxi device.' with button 'Download and install update'. Card 'Connect to configurator' with a key icon: 'Tunnel connection enables remote access to your Reduxi configurator, without need to be connected to the same local network.' and button 'Open configurator', marked with a cyan box and number badge 5. Below: card 'Unit details' with a field 'Unit ID' (value not visible). Right part: Reduxi Configurator opened in a browser, marked with a cyan frame and number badge 6. Header: back arrow, 'Tunnel connection', reload icon. Left sidebar with icons (lightning, chip, lightning bolt, bar chart, gear). Page 'Home' with a green link icon. Green notice: 'New patch available. Click here to apply.' with a close X. Time 09:12:56. Energy flow diagram with a house in the centre (1.700 kW) and icons for grid (0.000 kW), solar (1.700 kW), battery (green, 0.000 kW and 0.800 kW), a device at left (0.900 kW), electric vehicle and a charger or device at bottom. Label 'Energy manager' at the bottom.
http://reduxi.local. You can find the controller's IP address in your router's device list or in the Reduxi app under Reduxi devices.admin · Password: admin (factory default)Text description of this image
Screenshot of the Reduxi Configurator login page in a Chrome browser window. The address bar shows 'Not secure' and 'reduxi.local'; the address bar is marked with a cyan box and an enlarged copy of it (cyan box, text 'Not secure reduxi.local') is shown at the left, connected by a cyan line. Page background: light grey line drawing of a house with solar panels (green), a wall box, an inverter, a car and a charger. Top left: 'reduxi configurator' logo. Login box in the centre with title 'Login', a language selector (English flag, 'English'), a username field and a password field, and a dark 'Login' button.
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Screenshot of the Reduxi Configurator web interface after login, light theme. Top left: 'reduxi configurator' logo. Header bar: 'Home' at left, green 'Connected' status at top right. Left sidebar: expanded section 'Devices' with a list of entries, then collapsed sections 'Manager' and 'Configuration' and 'Settings'. Main area: energy flow diagram. House in the centre with ring, value 24.20 kW. Grid icon at top left, 24.20 kW (red dot on its line). Solar icon at top right, value '-'. Left icon (battery or device), 6.700 kW (green dot on its line). Right icons (battery storage and a device), values '-'. EV charger icon at bottom left, 31.00 kW. A further device icon at bottom right. Label 'Energy manager' below the house.
5 Add the energy meter to Reduxi
Use these steps to add a new energy meter or to edit an existing one.
5.1 Basic settings
Log in locally to the Reduxi Configurator on the controller (see Point 4) and click + Add device. Then enter the basic settings.
5.2 Communication settings
Select the communication channel. Then enter the device configuration.
| Parameter | Value |
|---|---|
| Modbus unit ID | Normally 1 is used. It must match the address set on the meter (Point 3). |
5.3 Advanced settings
Enter and choose the advanced settings.
5.4 Test communication
Click Test communication at the bottom of the wizard. It reads the the energy meter once and saves nothing. If the test succeeds, click Done: only Done creates the device.
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Screenshot of the bottom button bar of a Reduxi Configurator page. Left: button 'Back'. Right: button 'Test communication' (marked with a cyan box) and dark button 'Done'.
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Screenshot of the Reduxi Configurator page 'Communication channel and device configuration'. Connection *: TCP/IP (dropdown). IP *: 192.168.50.243, with button 'Scan for IP'. Port *: 502, with button 'Test port'. Modbus unit ID *: 1. Buttons at the bottom: Back (left), Test communication and Done (right). The Done button is marked with a cyan box.
6 Check the readings
6.1 Last measurements
After communication is established, check the values of the energy meter under Devices in the Reduxi Configurator as an additional test.
✓ Summary
Preparation (Points 1–2): Open the manufacturer documents and gather the Reduxi Controller, the RS485 cable and a laptop.
Energy meter (Point 3): Check the Modbus address, baud rate and parity on the meter.
Add to Reduxi (Points 4–5): Log in to the Reduxi Configurator, add the device and run Test communication.
Go live (Point 6): Check the readings of the meter under Devices.
→ Common issues
| Issue | Solution |
|---|---|
| Test communication fails | Check that the Modbus unit ID, baud rate and parity in Reduxi match the meter settings (Points 3 and 5.2). Check the RS485 wiring. |
| Open configurator does not open or stays empty | The tunnel is not active yet. Wait about 30 seconds and check that the controller is online. |
Login with admin is rejected |
The password was changed during installation. Ask the installer. The Reduxi account password does not work here. |
reduxi.local does not load |
Your device is not in the same network as the controller. Use the IP address or the tunnel connection. |
| Communication test fails, device shows offline | Check reachability, IP address / port / unit ID, and that the protocol is enabled on the device. |