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X. NMEA Settings and Autopilot Control
This chapter describes how to control NMEA 2000 (SeaTalk NG) autopilot from
the application using NMEA 0183 protocol and the settings available on the “NMEA
Settings” page of the administration web site.
1. True wind calculation
The wind sensor always measures apparent wind; true wind angle is calculated using
SOG or STW data and true wind direction requires COG or heading. A chart plotter
can join all these data and send calculated values to NMEA 2000, but usually TWD,
TWA and TWS are not available.
Historically, STW/HDG are used to calculate true wind. However, this is not correct
in places with strong current, and the «true» value of true wind can be obtained
using the SOG/HDG pair. Therefore, our gateways offers four options: SOG/HDG
(if you love truth), SOG/COG (if you have GPS only), STW/HDG (if tradition is most
important), or you can disable calculations. In the last case the gateway reports true
wind data only if they are calculated by another device available on NMEA 2000
network.
The default setting «Any» means that the gateway will detect what data are available
on the network and will calculate true wind data using the best possible option.
2. Talker ID
You can configure the talker ID (two next characters after $ or ! sign) for
NMEA 0183 output sentences. The default setting for the talker ID is «YD»
and gateway sentences looks like:
