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 (on Gen.1, additionally 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 — Enable USB data output¶

How data is output via USB depends on which generation of WattWächter you have. Check the product overview to identify yours.

Gen.2: Wi-Fi mode is always active. You enable USB data output additionally via a software command — no jumper configuration required. See Getting Started → Enable USB data output (Gen.2).
Gen.1: Reposition the jumpers on the circuit board to USB mode. See Getting Started → Select Operating Mode (Gen.1).

Step 2 — Connect WattWächter to Home Assistant¶

Reattach the WattWächter to your smart meter (on Gen.1, close the housing first)
Connect the WattWächter via USB-C cable to a free USB port on your Home Assistant server
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.

In Home Assistant, open Settings → System → Hardware
Click on All Hardware
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.

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¶

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

Step 5 — Enter the USB path¶

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

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).

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.

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

Troubleshooting¶

Problem	Solution
USB device does not appear (Gen.2)	Check that USB data output is enabled (`sensor53 u1`) and reconnect the cable
USB device does not appear (Gen.1)	Check the jumper position (USB mode) and reconnect the cable