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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

→ Tariffs, voltage, current, power, phase angles and device information: Additional OBIS codes.

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.