For: Operators using the Energy Portal

External meters let you connect non-Monta hardware to your site's load management. Use them to monitor power on nodes without replacing existing infrastructure.

Supported meter types

The Energy Portal supports four meter types. Each node can have one external meter at a time.

• Monta MQTT — Connect any MQTT-capable device. Publish meter data to Monta's broker using an auto-generated UUID.
• ABB Modbus — Connect an ABB meter already present on the site via a charge point identity.
• Perific — Connect a Perific hardware meter using its identifier.
• Viocon — Connect a Viocon hardware meter using its identifier.

Add an external meter

1. Open the Energy Portal at energy.monta.app.
2. Select your site from the sites list.
3. Go to Load Management.
4. Find the External Meters section and select Add Meter.
5. Select the node where the meter will be attached. Nodes with an existing meter are greyed out and cannot be selected.
6. Select your meter type.
7. Set the meter identity:

• Monta MQTT — A UUID is auto-generated. Copy it using the copy button — you need it to configure your MQTT client.
• ABB Modbus — Select a charge point identity from the list of EVSEs on the site.
• Perific — Enter the meter identifier (for example, PERIFIC-001).
• Viocon — Enter the meter identifier (for example, VIOCON-001).

1. Select Add External Meter.

The meter appears in the External Meters table, linked to its node.

Configure your MQTT client (Monta MQTT only)

After adding a Monta MQTT meter, connect your device to Monta's broker.

Get broker credentials

Broker credentials (username and password) are not generated automatically. Request them from your Monta representative or from support before connecting.

Connection details

• Broker: ssl://mqtt.monta.app:8883
• Topic: meter/monta/{your-meter-uuid}
• Protocol: MQTT over TLS (port 8883)

Publish meter data

Send JSON messages to the topic using this format:

{
  "meterUuid": "your-meter-uuid",
  "meterValues": {
    "currentL1A": 10.5,
    "currentL2A": 11.2,
    "currentL3A": 9.8,
    "voltageL1V": 230.0,
    "voltageL2V": 231.0,
    "voltageL3V": 229.5,
    "powerL1W": 2415.0,
    "powerL2W": 2587.2,
    "powerL3W": 2249.1,
    "powerW": 7251.3
  }
}

All fields in meterValues are optional. Include at least current or power per phase for accurate load management.

Field reference

• currentL1A, currentL2A, currentL3A — Amperes — Phase current
• voltageL1V, voltageL2V, voltageL3V — Volts — Phase voltage
• powerL1W, powerL2W, powerL3W — Watts — Phase active power
• powerW — Watts — Total active power
• measuredAt — ISO 8601 — Measurement timestamp (optional)

Once your device starts publishing, readings appear in the monitoring view and are used for load management.

Remove an external meter

1. Go to Load Management on your site.
2. Find the meter in the External Meters table.
3. Select the ⋮ (more options) button on the meter row.
4. Select Remove Meter.
5. Confirm by selecting Remove Meter in the dialog.

The meter is disconnected from the node. The physical device is not affected.