How to connect SAJ CM2 BESS with Reduxi controller
Integrate the SAJ CM2 BESS with the Reduxi Controller through Modbus TCP. This gives you maximum flexibility and lower cost and energy use.
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Product photo of the SAJ CM2 Smart C&I All-in-One BESS: a tall, narrow silver-grey cabinet with the SAJ logo at the top left, a black vertical strip on the front with small green and red indicator lights, a yellow warning sign near the lower right of the front door and a grille at the bottom, standing on a dark base. Background is a blue-grey gradient with diagonal light streaks.
1 Preparation
1.1 Technical documentation
- CM2 Quick Installation Guide – Quick installation guide for the SAJ CM2
- CM2 Full Installation Manual – Full user manual of the SAJ CM2
- SAJ CM2 series product page – Product page of the Smart C&I All-in-One BESS
1.2 Required equipment
- Reduxi Controller
- SAJ CM2 battery system (CM2-EMS BESS)
- Ethernet cable and a local router
- Laptop or tablet with internet access to configure the device in Reduxi
2 Connect the SAJ CM2 to the Reduxi Controller
2.1 Requirements
For the CM2-EMS BESS to communicate with the Reduxi Controller, you need two things:
- Modbus TCP/IP must be open.
- The IP address of the SAJ CM2 battery system.
2.2 Connect the SAJ CM2 to the local network
The SAJ CM2 and the Reduxi Controller must be on the same network.
- Connect the CM2 BESS to the local router through Ethernet. For detailed instructions, see the CM2 manual.
- The Modbus port 502 on the CM2 opens automatically when you connect it through Ethernet.
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Diagram of the network connection between a Reduxi Controller, a router and a SAJ CM2 battery cabinet, on a white background. Top left: black Reduxi Controller with the reduxi logo, label Controller. Middle: white Wi-Fi router with two antennas, label Router. Right: tall grey battery cabinet with SAJ logo at the top, black front strip and ventilation grille at the bottom. Lines: solid blue line labelled Ethernet from the Controller down to the Router; solid blue line labelled Ethernet from the Router to the SAJ cabinet; dashed light-blue line from the Router down to a globe icon with the letters WWW (internet).
3 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.
4 Add the SAJ CM2 to Reduxi
Use these steps to add a new SAJ CM2 or to edit an existing one.
4.1 Basic settings
Log in locally to the Reduxi Configurator on the controller (see Point 3) and click + Add device.
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Screenshot of the left sidebar of the Reduxi Configurator. Top: reduxi logo with the text CONFIGURATOR. Collapsed sections: Devices (plus icon) and Strategies (plus icon). Below, two buttons side by side: Add device (plus icon, marked with a blue highlight box) and Add strategy (plus icon). Below them two entries: Settings and Profile. The area to the right of the sidebar is empty white.
In the first step (basic settings), select the basic parameters of the device:
- Device type:
Hybrid Inverter - Type:
SAJ CM2 - Name: a name according to the model
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Screenshot of the Reduxi Configurator device wizard, step 1 Basic settings. Step indicator: 1 Basic settings (active), 2 Communication channel (greyed). Heading: Basic settings. Fields: Device type *: Hybrid inverter; Type *: Saj CM2; Name *: Saj CM2. Buttons: Back, Next.
4.2 Communication settings
Enter the Modbus ID and the IP address that you obtained from the SAJ CM2 system.
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Screenshot of the Reduxi Configurator device wizard, step 2 Communication channel. Step indicator: 1 Basic settings, 2 Communication channel (active). Heading: Communication channel and device configuration. Fields: Connection *: TCP/IP; IP *: empty, highlighted with a red box; Port *: 502; Modbus unit ID *: 1. Buttons: Back, Test communication, Done.
4.3 Test communication
Click Test communication at the bottom of the wizard. It reads the SAJ CM2 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.
If the test fails, check that you entered the correct Modbus ID and IP address. If the problem remains, contact the Reduxi Support Team.
5 Check the readings
5.1 Last measurements
After communication is established, check the values under Devices – SAJ CM2 in the Reduxi Configurator as an additional test.
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Screenshot of the Reduxi Configurator Last measurements view of the SAJ CM2 (page header and left menu not part of the image). Card Control type: toggle Auto (highlighted green) and Manual; timestamp 02. 10. 2025 16:10:53. Card Battery: Active power: -0.7 kW; Current: -2.10 A; Voltage: 316.90 V; Capacity: 7.3 kWh; Max. capacity: 10.1 kWh; State: DISCHARGING; State of charge: 72.00 %; State of health: 100.00 %; Min. state of charge: 0.00 %; Import active energy: 79.3 kWh; Export active energy: 70.2 kWh; Min. active power: -7.9 kW; Max. active power: 7.9 kW. Card PV: Active power: -0.2 kW; Current: -0.60 A; Voltage: 339.40 V; Export active energy: 70.5 kWh; Min. active power: -8.0 kW. Card Load: Active power: 0.9 kW; Import active energy: 196.7 kWh. Timestamps are 02. 10. 2025, between 16:11:18 and 16:11:20.
5.2 Enable control by Reduxi
For advanced battery control, integrate the device into the Reduxi strategy. Under Devices – SAJ CM2 in the Reduxi Configurator, set the control type to AUTO. Only then do strategy commands affect the battery.
To achieve maximum flexibility and energy cost reduction with dynamic prices and dynamic tariffs, define a strategy as described in Strategies for Reduxi controller.
After you add the device, you can also monitor and control it in the Reduxi application.
✓ Summary
Preparation (Points 1–2): Use the SAJ CM2 manuals. Connect the CM2 to the local router with Ethernet, on the same network as the Reduxi Controller.
SAJ CM2 (Point 2): Modbus TCP/IP must be open. Port 502 opens automatically. Note the IP address and the Modbus ID.
Add to Reduxi (Points 3–4): Log in to the Reduxi web interface. Add the device, enter the Modbus ID and the IP address, and run Test communication.
Go live (Point 5): Check the last measurements. Set the control type to AUTO and define a strategy.
→ Common issues
| Issue | Solution |
|---|---|
| Test communication fails | Check the Modbus ID and the IP address. Check that the SAJ CM2 and the Reduxi Controller are on the same network. Check that Modbus TCP/IP is open. |
| 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. |