External heading data is relevant for various applications, such as when instruments are mounted on buoys or attached to structures where a normal magnetic compass cannot be used. To enable the integration of an external GNSS compass, activate the external sensor functionality by sending the following command in the terminal:
SETEXTSENSOR,EN=1For more information about the command interface, see the Integrators Guide – Signature.
This command allows the Signature instrument to receive heading data from the GNSS compass via either a serial or Ethernet connection.
When enabled:
The instrument will use the external heading data when available.
If no external heading is detected, the instrument will automatically fall back to the internal compass.
Power considerations
Enabling the external sensor increases power consumption. If using Ethernet, the connection supports NMEA data transmission via UDP using port 9003, which allows both sending and retrieving data. Be aware that using the Ethernet port generally consumes more power than the serial connection.
Status messages
The instrument provides a status message indicating whether an HDT message has been received from the GNSS compass.
Which heading source is in use (HDT or the Signature’s internal compass) can be checked in the Extended Status bit when downloading data.
Example values:
40960(seen only once) =1010000000000000→ indicates a flush is happening.32768=1000000000000000→ means that the rest of the word (Extended Status) should be interpreted according to the bit structure.
For more details about how to interpret the Extended Status bit, please refer to the Integrators Guide – Signature.
Important note
If an HDT message is received, it replaces the Signature’s internal heading value in all calculations.
There will not be a separate file containing internal compass data that you can revert to.
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