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Home Assistant (USB)

The WattWächter WiFi/USB can be integrated directly into Home Assistant in USB mode via the EDL21 integration. In this mode, the WattWächter is connected via USB-C to the Home Assistant server (e.g. Raspberry Pi, NUC) and transmits data without going through WiFi.

Prerequisites

  • WattWächter WiFi/USB with access to the internals (for jumper configuration)
  • Home Assistant server with a free USB port
  • USB-C cable
  • Smart meter with an active SML data stream (PIN unlocked, Inf mode enabled)

Step 1 — Set jumpers to USB mode

The WattWächter ships configured for WiFi mode. For direct USB integration with Home Assistant, the jumpers need to be repositioned.

Important

Always disconnect the power supply before opening the housing!

Jumper positions for USB mode:

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

Jumpers USB mode

A detailed description of the jumper configuration can be found under Getting Started → Choose operating mode.

Step 2 — Connect WattWächter to Home Assistant

  1. Reattach the WattWächter to your smart meter and close the housing
  2. Connect the WattWächter via USB-C cable to a free USB port on your Home Assistant server
  3. The USB cable serves as both power supply and data line

Step 3 — Determine the USB device path

To let Home Assistant find the WattWächter, you need the USB device path.

  1. In Home Assistant, open Settings → System → Hardware
  2. Click on All Hardware
  3. Search for usb

You should see an entry like ttyUSB0 with a device path in the form /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0.

USB port in Home Assistant

Use a stable device path

Always use the path under /dev/serial/by-id/.... It remains stable across reboots and USB port changes — unlike /dev/ttyUSB0.

Step 4 — Add the EDL21 integration

  1. Open Settings → Devices & Services
  2. Click Add integration at the bottom right
  3. Search for edl21 and select the integration

Select EDL21 integration

Step 5 — Enter the USB path

In the dialog that follows, enter the USB device path from step 3 and confirm with OK.

Enter USB path

Step 6 — Name the device and assign an area

After a successful connection, Home Assistant creates a new device. You can assign a meaningful device name (e.g. Smart Meter) and an area (e.g. Basement).

Name device and assign area

Click Done to finish.

Step 7 — Verify the integration

The EDL21 integration now appears in the overview. Under the hub, you'll find the created device with its entities.

EDL21 integration with smart meter device

Click on the device to open the detail view with all sensors:

  • Current total active power (W)
  • Total negative active energy (Wh) — feed-in
  • Total positive active energy (Wh) — consumption
  • Meter point ID

Smart meter detail view

Troubleshooting

Problem Solution
USB device does not appear Check the jumper position (USB mode) and reconnect the cable