Filtering

lplex supports filtering frames by PGN, manufacturer, device instance, and CAN NAME. Filters can be applied at the API level (query parameters), in buffered sessions, and in lplexdump.

Filter types

Filter	Description	Example
PGN	NMEA 2000 Parameter Group Number (include)	129025 (position), 130306 (wind)
Exclude PGN	NMEA 2000 Parameter Group Number (exclude)	60928 (address claim)
Manufacturer	Device manufacturer name	Garmin, Victron
Instance	Device instance number (0-252)	0, 1
NAME	64-bit ISO 11783 CAN NAME (hex)	0x00A1B2C3D4E5F600

Filter logic

• Multiple values of the same type are OR'd: -pgn 129025 -pgn 129026 matches either PGN.
• Different filter types are AND'd: -pgn 129025 -manufacturer Garmin matches PGN 129025 frames only from Garmin devices.

(pgn=129025 OR pgn=129026) AND (manufacturer=Garmin)

lplexdump filters

Use repeatable flags:

# Wind and position data from Garmin
lplexdump -pgn 129025 -pgn 130306 -manufacturer Garmin

# Everything except address claims and product info
lplexdump -exclude-pgn 60928 -exclude-pgn 126996

# All data from device instance 0
lplexdump -instance 0

# Specific device by NAME
lplexdump -name 0x00A1B2C3D4E5F600

HTTP API filters

Ephemeral mode

Pass filter parameters as query strings on GET /events:

curl -N "http://inuc1.local:8089/events?pgn=129025&pgn=130306&manufacturer=Garmin"

# Exclude specific PGNs
curl -N "http://inuc1.local:8089/events?exclude_pgn=60928&exclude_pgn=126996"

Buffered mode

Set the filter when creating the session:

curl -X PUT http://inuc1.local:8089/clients/myapp \
  -d '{
    "buffer_timeout": "PT5M",
    "filter": {
      "pgn": [129025, 130306],
      "manufacturer": ["Garmin"]
    }
  }'

Values endpoint

Filter last-known values:

curl "http://inuc1.local:8089/values?pgn=129025&manufacturer=Garmin"

Resolved filters

When a filter uses manufacturer, instance, or name, lplex resolves these to source addresses at the time the filter is created. This means:

• Device-based filters don't require device registry lookups during iteration
• If a device changes its source address (e.g., address claim conflict), the filter may need to be recreated
• For ephemeral connections, filters are resolved on each new connection
• For buffered sessions, filters are resolved when the session is created

Filter object (JSON)

The filter object used in session creation and client libraries:

{
  "pgn": [129025, 129026, 130306],
  "exclude_pgn": [60928, 126996],
  "manufacturer": ["Garmin", "Victron"],
  "instance": [0, 1],
  "name": ["0x00A1B2C3D4E5F600"]
}

All fields are optional. An empty filter (or no filter) matches all frames. pgn (include) and exclude_pgn can be combined: include is checked first, then exclude.