Introduction

In 2024, wanting the power smart meter’s values in real time from inside the house, I started a homemade script to read Route B over a Wi-SUN USB dongle. But poking SK commands over serial, parsing ECHONET Lite, and the “I sent it but nothing comes back” timeout handling were tedious enough that I shelved it, vault notes and all. Years later, while messing with Home Assistant, I noticed a route_b_smart_meter official integration in Core that does the whole thing I never wrote. Plug in the dongle, enter the B-route ID and password, and instantaneous power and cumulative consumption appeared. A record of a tool catching up, after the fact, to something I’d given up on as “too tedious.”

Background — reading Route B yourself is quietly a pain

For a low-voltage smart meter, if you apply to your utility for Route B access, you can read ECHONET Lite directly over Wi-SUN from inside the house. The application issues an auth ID and password, and a Wi-SUN USB dongle lets you talk to the meter.

I understood that much. The problem was what came after. Talking to the dongle means poking SK commands (SKVER / SKSCAN / SKSENDTO …) over serial and assembling and parsing ECHONET Lite frames yourself. The requirements memo I left in the vault back then literally says:

• Timeout handling — required, because sometimes you send data and nothing comes back
• Decode handling — need to consider cases that won’t decode as unicode

In short, you have to write endless tedious serial-comms error handling. It looked fun, but I put it off. That note sank into the Archive with a “someday” verdict.

I left it alone, and the official one caught up

Years later, while messing with Home Assistant, I noticed a route_b_smart_meter (Route B Smart Meter) integration running.

At first I figured “I probably grabbed it from HACS.” But checking, it’s neither in custom_components/ nor in the HACS installed list. In HA’s startup log, the custom-integration warning (“We found a custom integration …”) shows only for my other homemade things, not for route_b_smart_meter. The punchline: it’s a first-party core integration with official docs.

In other words, the SK-command serial poking + ECHONET Lite parsing + retries that I’d skipped “because it’s tedious” — HA core now does all of it internally.

Implementation — three fields in a config form

1. Apply for Route B access (apply to the utility → an auth ID and password arrive). I’d done this long ago.

2. Plug in the Wi-SUN USB dongle. For a unit that shows up as an FTDI serial, the path looks like:

   /dev/serial/by-id/usb-FTDI_FT230X_Basic_UART_XXXXXXXX-if00-port0

3. Add the integration in HA → just enter device (the serial path above) / B-route ID / password.

4. Sensors appear:

   Sensor	Content
   Instantaneous power	how many W right now
   Instantaneous current (R/T phase)	current per phase
   Cumulative consumption	running kWh total

I didn’t write a single line of code. The processing I tried and abandoned in 2024 came down to three fields in a config form.

Gotchas

• The B-route ID goes straight into the entity ID. The auth ID becomes part of the entity name, like sensor.route_b_smart_meter_XXXXXXXX_total_consumption. Leak it via a screenshot or a YAML copy-paste and it’s exposed, so mask it when sharing or writing it up (I’ve replaced it with XXXXXXXX here too).
• Connecting can take a while. The “nothing comes back” problem I got stuck on is alive and well; the integration retries internally. Be patient with the first scan.
• Route B basically allows one concurrent connection. If another device (a HEMS, say) is holding the meter, it conflicts.
• There’s dongle / Wi-SUN version dependence. I use a dongle that shows up as FTDI. Check whether yours is supported beforehand.

Results

Once you have the sensors, the rest is HA’s world. I wired it up like this:

• Aggregate the cumulative consumption daily with utility_meter to make “today’s power use.”
• Use that to have my Echo Dot announce, every day at 21:00, “Here’s today’s power report. Today’s electricity is about ¥◯◯,” an automation (consumption × unit price for a rough estimate).
• And if instantaneous power exceeds 2000W for 5 minutes, Alexa warns me. Useful when the AC and microwave pile up, say.

I recovered the value of the script I never wrote in 2024 “because it was tedious,” at zero code. The announcement side’s build-out is continuous with another post (the HA × Alexa story).

Wrap-up

• Reading a smart meter’s Route B yourself needs SK-command serial poking + ECHONET Lite parsing + error handling. Tedious, so I’d shelved it.
• While I left it alone, an official route_b_smart_meter integration landed in HA Core, and a dongle + B-route ID / password is all it takes to get instantaneous power and cumulative consumption.
• Things you “wanted to do but gave up on as tedious” sometimes have a tool (HA core, this time) catch up later. Shelved notes are worth revisiting now and then.
• When publishing, don’t forget to mask the B-route ID (it sneaks into the entity ID) and the password.

References

• Route B Smart Meter — Home Assistant official integration