Huawei EMMA (grid)
The Huawei EMMA (Energy Management Assistant) is a residential energy management controller that integrates metering, communication, and load coordination in a single unit. This ModbusCloud template reads the EMMA's built-in grid meter via Modbus TCP, capturing grid power, cumulative energy, and per-phase currents (A, B, C) at the grid connection point. The sign convention follows Huawei documentation: positive values indicate power fed to the grid, negative values indicate power drawn from the grid. With these readings in your ModbusCloud portal, you can track import and export behaviour in real time alongside your full Huawei PV and storage installation.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 5, read only
- Brand
- Huawei
- Last updated
Registers (5)
5 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| energy | Wh | Read | |||
| currents_a | A | Read | |||
| currents_b | A | Read | |||
| currents_c | A | Read |
Loading registers…
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Use cases
- Monitor real-time grid import and export power to verify that the EMMA's feed-in limit is being respected.
- Track cumulative grid energy to calculate net import costs over billing periods and compare against PV yield.
- Alert on sustained negative power values indicating unexpected grid draw outside expected self-consumption windows.
- Compare per-phase currents on phases A, B, and C to detect load imbalances across the three-phase connection.
- Verify that grid power drops to near zero during battery discharge cycles, confirming correct ESS operation.
Installation
Enable Modbus TCP on the EMMA using the FusionSolar app: open the app, select Services, Commission the device, Communication Settings, then Modbus TCP, and set TLS to disabled and enter the client IP of the ModbusCloud Gateway.
Connect the ModbusCloud Gateway by Ethernet to the same network as the EMMA, ensuring port 502 is reachable from the Gateway to the EMMA's IP address.
In the ModbusCloud portal, add the Gateway, import the Huawei EMMA (grid) template, and assign the correct unit ID (typically 0 for the EMMA's built-in meter).
Spot-check the power register (address 31657) in the portal live view and confirm the sign and magnitude match the FusionSolar app's grid power reading at the same moment.
Things to watch for
Port 502 is open but all registers return errors. Why?
The EMMA requires Modbus TCP to be explicitly enabled via the FusionSolar app using installer credentials. Without this step the service is inactive even if the port appears reachable. Also confirm TLS is disabled in the communication settings, as an encrypted connection will reject plain Modbus frames.
Grid power reads zero even though energy is clearly flowing. What is wrong?
Check that the correct unit ID is configured. The EMMA uses logical device addressing in Modbus TCP frames, so a mismatched unit ID returns no data rather than an error. Confirm the unit ID with the installer documentation and update it in the template assignment.
Power values look inverted: positive when drawing from grid, negative when exporting.
The Huawei EMMA sign convention is: positive means power fed to the grid, negative means power supplied from the grid. If your dashboard logic expects the opposite convention, apply a scaling factor of minus one on the power and energy registers in the ModbusCloud portal channel settings.
Phase current registers show large inconsistent values between polling cycles.
The int32 current registers span two consecutive Modbus registers and use big-endian byte order as documented in the Huawei SmartHEMS Modbus interface specification. Verify that the Gateway reads the full two-register block in a single request and that big-endian word order is selected in the template, otherwise the high and low words will be swapped.
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