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["📡 MQTT"]
    WW -- WiFi --> Cloud["☁️ Cloud Portal"]

The IR reading head receives SML telegrams from the smart meter
The WattWächter parses OBIS codes (e.g., 1-0:1.8.0 for total consumption)
Data is stored internally (15-min resolution: 30 days, daily values: 2 years)
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 authentication

curl -X POST http://wattwaechter-XXXXXXXXXXXX.local/api/v1/settings \
  -H "Content-Type: application/json" \
  -d '{"api_auth_required": true}'

Tokens are passed via header:

Authorization: Bearer YOUR_TOKEN

MQTT Integration¶

The WattWächter can send telemetry data via MQTT to a broker — ideal for Home Assistant, ioBroker, and other smart home systems.

Configure MQTT

curl -X POST http://wattwaechter-XXXXXXXXXXXX.local/api/v1/settings \
  -H "Authorization: Bearer WRITE_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"mqtt": {"enable": true, "host": "mqtt.example.com", "port": 8883}}'

TLS with custom CA certificate

For MQTT brokers with a self-signed certificate:

curl -X POST http://wattwaechter-XXXXXXXXXXXX.local/api/v1/mqtt/ca \
  -H "Authorization: Bearer WRITE_TOKEN" \
  -H "Content-Type: text/plain" \
  --data-binary @my_broker_ca.pem

Troubleshooting¶

Device not reachable

Check LED status
Test ping: ping wattwaechter-XXXXXXXXXXXX.local
Find IP address
If LED is solid red: restart device (disconnect/reconnect USB)

No meter data

Is the IR reading head correctly placed on the optical interface?
Smart meter unlocked? → Meter Preparation
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.