MQTT Energy Meter: Publish IAMMETER Data to Your MQTT Broker

Publish IAMMETER Energy Data to an MQTT Broker

IAMMETER Wi-Fi energy meters can work as MQTT energy meters and publish real-time voltage, current, active power and energy data directly to your own MQTT broker. This provides a local and open way to integrate IAMMETER with a custom monitoring system, automation platform or Home Assistant.

The latest IAMMETER firmware lets you configure the MQTT connection directly from the meter's local WebUI.

1. Configure MQTT Publishing

1.1 MQTT Settings

Open the meter's local WebUI and go to the Settings page. Configure the MQTT connection using the fields shown below:

Setting	Configuration
Run Mode	Select MQTT
Address	Enter the MQTT broker address and port
Username/Password	Enter the broker credentials; leave blank only if anonymous connections are allowed
HA MQTT Discovery	Enable only for Home Assistant automatic discovery
Real-time topic	device/{SN}/realtime

After completing the settings, click Save. The meter will connect to the configured broker and publish its measurement data as an MQTT client.

The latest firmware WebUI supports the MQTT settings described above. There is no need to configure the broker username and password through a local API.

1.2 When to Enable HA MQTT Discovery

HA MQTT Discovery is only used for Home Assistant automatic discovery.

• If you are publishing data to a general MQTT broker or another third-party system, keep HA MQTT Discovery disabled.
• If Home Assistant is connected to the same MQTT broker and you want it to automatically discover the IAMMETER meter and create the corresponding device and sensor entities, enable HA MQTT Discovery.
• Enabling MQTT publishing does not require enabling HA MQTT Discovery. These are related but separate functions.

For the complete discovery procedure, see Enable MQTT Discovery in Home Assistant with IAMMETER. To compare MQTT Discovery with IAMMETER's other Home Assistant integration methods, including the official integration, Modbus/TCP and manual MQTT configuration, start from the IAMMETER Home Assistant integration guide.

2. MQTT Topic and Payload

2.1 Subscribe to the Real-time Topic

Topic: device/{SN}/realtime

Replace {SN} with the serial number of your IAMMETER meter. After the meter connects to the MQTT broker successfully, an MQTT client can subscribe to this topic to receive real-time measurement data.

2.2 Interpret the JSON Payload

Regardless of whether the meter is configured to upload data to a third-party server using HTTP/HTTPS, TCP/TLS or MQTT, or measurement data is retrieved through a local API, the measurement JSON format remains consistent.

For example, a single-phase meter publishes a Data array containing voltage, current, active power, forward active energy and reverse active energy:

{
  "method": "uploadsn",
  "mac": "B0F8932A295C",
  "version": "i.75.98.71y",
  "server": "em",
  "SN": "12345678",
  "Data": [228.91, 1.61, 225, 15066.47, 0]
}

Three-phase meters use a Datas array with separate measurement arrays for phases A, B and C. See the complete IAMMETER JSON data definition before parsing the payload in a third-party application.

3. Related Guides

• Upgrade to the latest IAMMETER firmware
• Enable MQTT Discovery in Home Assistant with IAMMETER
• IAMMETER MQTT JSON data format
• Other ways to integrate IAMMETER with a third-party server

4. Configuration for Older Firmware

The instructions below are retained for meters that still use an older firmware version and do not provide the current MQTT configuration options in the WebUI.

If your meter's WebUI looks like the screenshots below, follow this legacy procedure. Alternatively, upgrade to the latest firmware and use the WebUI procedure in Section 1.

4.1 Legacy Device Configuration

Configure the upload mode and MQTT broker address as follows:

• Run Mode: TCP
• TCP Address: mqtt://[URL of your MQTT server]:[port]

4.2 Legacy Username and Password Configuration

Username and password configuration requires firmware i.75.97.5 or later.

In this mode, the Wi-Fi energy meter works as an MQTT client and supports the following broker authentication methods:

1. Username and password
2. Client ID, using the meter's serial number as the Client ID
3. Anonymous connection

On older firmware, set the MQTT username and password through the meter's local API:

http://{local IP of the energy meter}/api/mqtt?user=laoliu&pwd=123456

Replace laoliu and 123456 with the actual MQTT broker username and password.

Legacy configuration notes:

• The maximum length of both the username and password is 20 characters.
• The & character is not supported in the username or password.

To retrieve the current MQTT authentication setting, use:

http://{local IP of the energy meter}/api/mqtt

The API does not return the MQTT password itself; it only returns the password length.