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Getting Started

The WattWächter WiFi/USB arrives fully assembled with pre-installed software. For setup you need:

Prepare the meter first

Before connecting the WattWächter, your electricity meter must be unlocked (PIN from your grid operator). Follow the Meter Preparation guide to do so.

1. Select Operating Mode

How you set the operating mode depends on your WattWächter's generation. You can identify yours from the product overview.

On Gen.2 the Wi-Fi mode is always active — no jumper configuration required. For the Wi-Fi setup, skip ahead to Step 2.

Optional: USB data output

Data can additionally be made available via the USB interface (e.g. for a direct connection to a computer or Raspberry Pi). This is configured via the WattWächter's web interface and is therefore only possible once the Wi-Fi connection has been established — see Enable USB data output at the end of the page.

On Gen.1 the operating mode is set via jumper positions on the circuit board. Wi-Fi mode is pre-configured at the factory.

Warning

Always disconnect the power supply before opening the housing!

PIN assignment for operating modes:

PIN assignment operating modes

Wi-Fi Mode (factory default)

In Wi-Fi mode, the WattWächter connects to your existing Wi-Fi network. Data can be retrieved via web browser or MQTT.

Jumper positions:

  • PIN 02 & 03
  • PIN 08 & 09
  • PIN 06 & 12

Jumper Wi-Fi mode

USB Mode

In USB mode, the WattWächter transmits data directly via USB-C to a computer or Raspberry Pi. The USB cable serves as both power supply and data connection.

Jumper positions:

  • PIN 03 & 04
  • PIN 09 & 10
  • Optional: PIN 06 & 12

Jumper USB mode

2. Connect Power Supply

Connect the WattWächter via a USB-C cable to a power adapter (5 V, min. 500 mA, max. 15 W) or a battery pack. The blue LED (RX) lights up continuously once the WattWächter is powered.

Power banks not recommended

Conventional power banks often have an auto-shutoff feature that deactivates the output at low power draw (< 0.5 W). Use a battery pack without auto-shutoff instead.

USB Mode

In USB mode, the USB-C cable serves as both power supply and data connection.

3. Set Up Wi-Fi

After powering on, the WattWächter creates its own Wi-Fi network named "WattWaechter-..." (followed by an alphanumeric identifier).

  1. Connect to this network (no password required)
  2. Open a web browser and navigate to 192.168.4.1
  3. Select your local Wi-Fi network and enter the password

Tasmota Wi-Fi configuration

After a successful connection, the WattWächter displays its new local IP address.

Tasmota Wi-Fi connected

Tip

Write down the displayed IP address – you'll use it to access the WattWächter's web interface on your local network.

4. Configure Meter Script

Depending on your meter type, a matching script needs to be configured. An overview of available scripts can be found at Meter Scripts.

  1. Open the WattWächter's web interface using the IP address noted earlier
  2. Navigate to Tools → Edit Script
  3. Enable the Script enable checkbox
  4. Paste the complete script for your meter type
  5. Click Save

Tasmota script configuration

5. Position the Sensor Head

The WattWächter attaches magnetically to the meter. Position it directly over the IR interface (infrared diodes) of your smart meter – typically with the cable facing upward.

PIN activation required

For your meter to transmit measurement data via infrared, the extended data display must be activated on the meter. You need the PIN code from your grid operator. Enter it directly on the meter, then set PIN to Off and Inf to On in the meter menu.

Once everything is set up correctly, the measurement values will be displayed in the WattWächter's web interface.

Optional: Enable USB data output (Gen.2)

On Gen.2 Wi-Fi mode is always active. In addition, data can also be made available via the USB interface — e.g. to connect the WattWächter directly to a computer or Raspberry Pi.

Only possible after Wi-Fi setup

USB data output is enabled via the WattWächter's console or web interface. You can only reach it after you have established the Wi-Fi connection (Step 3).

Option 1 — Via console command (one-shot)

Open the WattWächter console and enter:

sensor53 u1

USB data output is enabled immediately. The setting is not stored persistently and resets after a reboot.

Option 2 — Via script (persistent on boot)

To enable USB data output automatically after every reboot, add the following line to the boot block >B in the script editor (Console → Edit script):

>B
=>sensor53 u1

After saving and rebooting, the WattWächter enables USB data output automatically on startup.