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WattWächter Plus

WattWächter Plus

The WattWächter Plus reads energy data from your smart meter via an IR reading head and makes it available locally and through the cloud.

Features

  • Real-Time Monitoring

    Current power (W) and meter readings (kWh) directly from your smart meter

  • WiFi & Bluetooth 5.0

    Wireless connection to your home network and easy setup via app

  • REST API

    Full access to all data via local endpoints

  • Cloud Portal

    Remote access via the Cloud Portal

  • MQTT

    Integration with Home Assistant, ioBroker, and other smart home systems

  • OTA Updates

    Automatic firmware updates via the cloud

How It Works

flowchart LR
    SM["Smart Meter"] -- IR --> WW["⚡ WattWächter"]
    WW -- WiFi --> API["🌐 REST API"]
    WW -- WiFi --> MQTT["<span style='display:inline-flex;align-items:center;gap:4px;white-space:nowrap'><img src='/assets/images/mqtt-logo.svg?v=2' style='width:14px;height:14px'/>MQTT</span>"]
    WW -- WiFi --> Cloud["☁️ Cloud Portal"]
  1. The WattWächter receives SML telegrams from the smart meter
  2. The WattWächter parses OBIS codes (e.g., 1-0:1.8.0 for total consumption)
  3. Data is stored internally (15-min resolution: 30 days, daily values: 2 years)
  4. Served via REST API, MQTT, and/or cloud portal

Specifications

Property Value
Connectivity WiFi 802.11 b/g/n, Bluetooth 5.0 LE
Interface IR reading head (SML/OBIS protocol, D0 interface)
Power supply USB-C, 5V (min. 500mA)
Storage 15-min resolution (30 days) + daily values (2 years)
Status indicator RGB LED (meaning)
Hostname wattwaechter-XXXXXXXXXXXX.local (mDNS)

Data Collection

OBIS Codes

The following OBIS codes are provided by nearly all modern meters after unlocking:

OBIS Code Description Unit
1-0:1.8.0 Total consumption (import) kWh
1-0:2.8.0 Total feed-in (export) kWh
1-0:16.7.0 Current power W
Additional OBIS codes

Which additional OBIS codes your meter provides depends on the manufacturer's or network operator's configuration and cannot be changed — even if the meter's display shows more values. The WattWächter delivers all values it receives from the meter. You can check which ones are available in the web UI under Live Dashboard → All meter values or via the API at /api/v1/history/latest.

Tariffs

OBIS Code Description Unit
1-0:1.8.1 Consumption tariff 1 kWh
1-0:1.8.2 Consumption tariff 2 kWh
1-0:1.8.3 Consumption tariff 3 kWh
1-0:1.8.4 Consumption tariff 4 kWh
1-0:2.8.1 Feed-in tariff 1 kWh
1-0:2.8.2 Feed-in tariff 2 kWh
1-0:2.8.3 Feed-in tariff 3 kWh
1-0:2.8.4 Feed-in tariff 4 kWh

Voltage, Current & Power

OBIS Code Description Unit
1-0:14.7.0 Frequency Hz
1-0:32.7.0 Voltage L1 V
1-0:52.7.0 Voltage L2 V
1-0:72.7.0 Voltage L3 V
1-0:31.7.0 Current L1 A
1-0:51.7.0 Current L2 A
1-0:71.7.0 Current L3 A
1-0:21.7.0 Power L1 W
1-0:41.7.0 Power L2 W
1-0:61.7.0 Power L3 W

Phase angles

OBIS Code Description
1-0:81.7.1 Phase angle U L2/L1
1-0:81.7.2 Phase angle U L3/L1
1-0:81.7.4 Phase angle I/U L1
1-0:81.7.15 Phase angle I/U L2
1-0:81.7.26 Phase angle I/U L3

Device information

OBIS Code Description
1-0:0.2.0 Firmware version
1-0:0.9.1 Time
1-0:96.50.1 Manufacturer code
1-0:96.1.0 Meter number

Authentication

The API is accessible without authentication by default. For shared networks, we recommend enabling token-based authentication.

Token Permission
READ Token Fetch data, check status
WRITE Token Change settings, start OTA, reboot

→ Enable and manage tokens: Settings → API Authentication. HTTP details and token rotation: REST API.

MQTT Integration

The WattWächter can send telemetry data via MQTT to a broker — ideal for Home Assistant, ioBroker, and other smart home systems. Topic structure, payload format and Home Assistant auto-discovery are documented under Interfaces → MQTT.

→ Configure broker, port, publish interval and CA certificate: Settings → MQTT.

Home Assistant

A dedicated Home Assistant integration with auto-discovery is available — see Integrations → Home Assistant.

Troubleshooting

Device not reachable
  1. Check LED status
  2. Test ping: ping wattwaechter-XXXXXXXXXXXX.local
  3. Find IP address
  4. If LED is solid red: restart device (disconnect/reconnect USB)
No meter data
  1. Is the IR reading head correctly placed on the optical interface?
  2. Smart meter unlocked? → Meter Preparation
  3. Check values: curl http://wattwaechter-XXXXXXXXXXXX.local/api/v1/history/latest
Factory Reset

Hold the function button for 7 seconds. All data will be deleted.