M-Tec MTec
The M-Tec MTec is a hybrid battery storage inverter from Austrian manufacturer M-TEC, part of the Energy Butler product family. It combines a PV inverter with integrated battery management and communicates over Modbus RTU. This template reads instantaneous AC output power (register 706), accumulated energy (register 707), and internal temperature (register 401). A write register at address 1000 lets your control system cap the inverter's maximum output power. Connecting this template in ModbusCloud gives installers and asset managers live visibility and setpoint control across one or more M-Tec sites.
- Protocol
- Modbus RTU
- Connection
- RS485
- Registers
- 4, read and write
- Brand
- M-Tec
- Last updated
Registers (4)
3 read, 1 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| setmaxpower | W | Write | |||
| power | W | Read | |||
| energy | Wh | Read | |||
| temp | °C | Read |
Loading registers…
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Monitor instantaneous AC output power to verify inverter operation at expected load levels.
- Track accumulated energy over time to validate production figures against utility billing data.
- Alert on temperature readings that exceed normal operating thresholds to catch cooling issues early.
- Apply a maximum power setpoint remotely to limit export during grid curtailment events.
- Compare energy readings across multiple M-Tec MTec units on multi-site dashboards.
Installation
Enable Modbus RTU on the M-Tec MTec inverter by confirming the espressif gateway device is active on your local network and note its IP address and port (default port 5743, or 502 on firmware V27.52.4.0 and later).
Connect the ModbusCloud Gateway to the same LAN segment as the espressif Modbus server, ensuring the Gateway can reach the inverter's IP address and port over TCP.
In the ModbusCloud portal, add a new device, import the M-Tec MTec template, and set the Modbus unit ID to 252 (the default slave ID for this device) under the communication settings.
Verify the connection by spot-checking register 707 (power) in the live data view; a non-zero signed integer confirms the inverter is responding correctly.
Things to watch for
No values appear after import, though the gateway connects.
Confirm the Modbus framer is set to RTU, not plain TCP socket mode. The M-Tec MTec uses RTU framing over TCP via the espressif server. Also verify the slave ID is 252 and the port matches your firmware version: 5743 for firmware before V27.52.4.0, or 502 for that version and newer.
Power and energy registers return zero or implausible values.
Registers 706 and 707 are signed 16-bit integers. If your polling tool or gateway interprets them as unsigned, large negative values will appear as very high positive numbers. Ensure the data type is configured as int16. Also check that the inverter is actively running, as some devices report zero when idle.
Temperature register 401 reads a value that seems too high or too low.
Confirm whether a scaling factor applies. M-TEC Modbus documentation for similar devices sometimes encodes temperature as tenths of a degree Celsius (value divided by 10). Cross-check the raw register value against the inverter's local display or portal to determine the correct scaling for your firmware version.
Is it safe to write to the setmaxpower register at address 1000?
Use the setmaxpower write register with care. Setting a value below the inverter's configured minimum or above its rated capacity can trigger protection responses or affect warranty conditions. Always test with conservative values, confirm the inverter accepts the setpoint via the power register, and coordinate with the M-TEC installer before enabling automated writes.
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