2. Discover ECUs¶

canair discover sweeps a range of CAN addresses, sends each a diagnostic session request (10 01), and classifies which ones respond. Crucially, with --register it writes the responders into your profile's ecus/ — so discovery is how your empty profile gets its first content.

Sweep and register¶

canair discover --register

This probes the default address range (700–7EF, where most OBD-II ECUs live), then adds a file under ecus/ for each newly-found ECU. Preview without writing:

canair discover --register --dry-run

Already-registered ECUs are skipped, so it's safe to re-run as you find more.

Also read identity in one pass¶

Add --identify to run identity decoding on each live ECU right after the sweep — pulling part numbers, hardware/software versions, and the VIN where available:

canair discover --register --identify

Useful options¶

Flag	Why
`--range START-END`	Scan a different address range, e.g. `--range 600-6FF`
`--delay SECONDS`	Slow the pacing for finicky/slow buses (default `0.2`)
`--dry-run`	With `--register`, preview additions without writing
`--save`	Also record the sweep result to `captures/`
`--json`	Machine-readable output

What gets written¶

Each newly-registered ECU becomes an ecus/<name>.yaml file with a placeholder name (derived from its address), its TX/RX addresses, and a note recording when and how it was discovered. You'll rename and enrich these as you learn what each one is — the identity step is the fastest way to start.

Confirm what landed:

canair ecu            # list registered ECUs
canair validate all   # everything still valid

No car handy? (starting a profile offline)¶

discover needs a live vehicle. If you're bootstrapping a blank profile for contribution — e.g. seeding one ECU you know exists from another model-year — register it offline with canair ecu add (the offline counterpart to discover --register; the write is validated and comment-preserving, never hand-editing ecus/):

canair --profile my-car ecu add 7C6 --name CLU \
    --description "Cluster (instrument panel)" \
    --notes "Shares 0x7C6 with another model-year; no PIDs decoded yet."

Flags: --name (defaults to Unknown-<TX>), --description, --id-protocol (UDS/KWP2000), --notes, --overwrite (replace existing identity fields), and --dir (target a specific ecus/). Re-running with the same TX is idempotent. Everything after this step assumes you'll enrich the ECU with a live car.

Next: 3. Read identity →