UDP input format

To send sensor measurements to the Hub, connect your device to the Hub’s Wi-Fi network and broadcast UDP messages on the appropriate port below. Each message contains the measurement and status information reported by your device.

Input ports

Send 1–50 messages per second for each input. For analog inputs, send each channel on its own port.

Connection and measurement status

The Hub marks an input disconnected if no message arrives for five seconds. It checks each analog channel separately. Keep transmitting at 1–50 Hz during normal operation.

These indicators describe different conditions:

A connected sensor can still report a measurement problem. Check health and, where provided, availability and range status before using a value. A value can remain in the log after the sensor disconnects. Use the new-measurement flag to distinguish a new sensor reading from a repeated one.

Encoding

Each message begins with a version byte, followed by the fields in table order. The Type column gives each field’s size:

The Scale column describes how the Hub converts a stored integer to a measurement. To send a measurement, divide it by that scale. For example, send an OAT of 20.5°C as the signed integer 2050, because the scale is 1 / 100. Follow the description for fields with offsets or status bits. These UDP messages have no log-file header, payload length, or Fletcher-16 checksum.

Send multibyte fields in little-endian order, least significant byte first, with no padding between fields. Air-data version 0 messages are 22 bytes and version 1 messages are 28 bytes. Analog values use IEEE-754 single-precision floating point.

Air data

Port 2001 · input · 1-50 Hz

The Hub can receive external static/differential pressure, airspeed, altitude, wind, outside-air-temperature, and angle-of-attack measurements. The Hub forwards indicated and true airspeed through its GDL 90 AHRS output, subject to the connection and availability rules described there.

Compatibility

Air-data message v1 was introduced in Hub firmware 3 and adds CAS and wind estimates. It requires firmware 3 or later and is not compatible with firmware 1 or 2. External-device developers should support both message versions and let users select the version appropriate for their Hub firmware.

The receiver accepts version 0 only when the message is exactly 22 bytes. For version 1 or higher, it requires at least 28 bytes and reads the version 1 fields. It ignores any bytes after those fields. A newer sender must therefore keep the version 1 fields in the same positions and use the same encoding.

Version 0 fields

Version 1 fields

For both versions, decode aoa as the signed integer divided by 100. Status bit 0x2000 selects degrees when set and a dimensionless pressure ratio when clear. For example, a stored value of 125 represents 1.25 degrees or a ratio of 1.25.

Status flags

A set bit has the meaning below. CAS and wind availability (0x4000, 0x8000) were added in version 1.

External AGL altimeter

Port 2002 · input · 1-50 Hz

The external AGL message provides measured height above ground for analysis of approach, flare, landing, and rollout.

AGL status

Analog inputs

Ports 2006-2009 · input · 1-50 Hz per channel · introduced in firmware 6

Up to four analog channels are supported. A device may measure one channel or all four. Send each channel independently to its assigned port: channel 0 → 2006, channel 1 → 2007, channel 2 → 2008, channel 3 → 2009.

The table below describes one channel. voltage is the measured input voltage. value is the reading after calibration, stored as a 32-bit floating-point number. Its units depend on the external device.

Analog status