EnviroLink- NMEA 2000 Barometer & Marine Weather Station

What NMEA 2000 data does EnviroLink use?

EnviroLink automatically detects and uses compatible data available on the NMEA 2000 network, including:

• PGN 130306 – Wind Data: wind speed, wind angle, and wind reference
• PGN 127250 – Vessel Heading: used when a north-referenced wind direction must be calculated
• PGN 130316 – Water Temperature: used for water temperature logging

No manual configuration is normally required.

Which types of wind data are supported?

EnviroLink supports all common NMEA 2000 wind references:

• True Wind Direction / True Wind Speed (TWD/TWS)
• True Wind Angle / True Wind Speed (TWA/TWS)
• Apparent Wind Angle / Apparent Wind Speed (AWA/AWS)

The wind reference is automatically identified from the Wind Data PGN (130306).

How does EnviroLink choose which wind source to use?

If multiple wind instruments are present on the network, EnviroLink automatically selects the best available source using the following priority:

1. True Wind Direction / True Wind Speed (TWD/TWS)
2. True Wind Angle / True Wind Speed (TWA/TWS)
3. Apparent Wind Angle / Apparent Wind Speed (AWA/AWS)

If more than one device provides the same type of data, EnviroLink selects the first valid source based on its NMEA 2000 source address.

This ensures the most useful wind information is logged without requiring manual source selection.

How is wind direction determined?

The method depends on the type of wind data available.

1. True Wind Direction (TWD)
   If True Wind Direction is available, it is already referenced to north.
   EnviroLink logs the wind speed and direction directly.
2. True Wind Angle (TWA)
   If True Wind Angle is received, EnviroLink uses the vessel heading to calculate a north-referenced wind direction:
   Wind Direction = Vessel Heading + True Wind Angle
   The result is normalised to a value between 0° and 360°.
   If heading data is unavailable, EnviroLink still logs the wind speed, but the wind direction is recorded as unavailable.
3. Apparent Wind Angle (AWA)
   If only Apparent Wind Angle is available, EnviroLink can estimate a north-referenced wind direction using the vessel heading.
   This assumes little or no vessel movement through the water, where Apparent Wind Angle closely approximates True Wind Angle.
   When heading data is unavailable, only wind speed is logged.

What does a wind direction value of 999 mean?

A value of 999 indicates that wind direction could not be determined.

This typically occurs when EnviroLink receives wind speed and a relative wind angle (TWA or AWA), but no valid vessel heading is available to calculate a north-referenced direction.

What is the fixed_wind_sensor_north option?

Some fixed wind sensors provide wind direction already referenced to north rather than relative to the vessel.

When fixed_wind_sensor_north is enabled, EnviroLink treats the received angle as an absolute direction and logs it directly without applying the vessel heading.

What happens if wind data is lost?

Wind and heading data are considered invalid if no new data is received for 10 seconds.

If this timeout is exceeded, EnviroLink stops using the stale values for subsequent log entries, ensuring recorded data reflects the current network status.

Does EnviroLink log True Wind Angle (TWA)?

No. EnviroLink does not log or display True Wind Angle (TWA) as a separate parameter.

Instead, EnviroLink records a north-referenced wind direction (0–360°) whenever it can be determined.

Depending on the data available on the NMEA 2000 network, this may be:

• True Wind Direction (TWD) received directly from a wind instrument.
• Wind Direction calculated from True Wind Angle (TWA) using the vessel heading.
• Wind Direction calculated from Apparent Wind Angle (AWA) using the vessel heading when no true wind direction is available.

If heading data is unavailable, EnviroLink records the wind speed but marks the wind direction as unavailable.