Appendix B - Nmea 2000 Interfacing - Maretron SSC300 User Manual

Appendix B – NMEA 2000
SSC300 NMEA 2000
PGN 127250 – Vessel Heading
The SSC300 uses this PGN to indicate the vessel's heading. The Heading Sensor Reading (field
2) includes deviation, therefore Deviation (field 2) always contains zero. Variation (field 4) is not
provided by the SSC300, therefore this field always contains a value of 0x7FFF (data not
available). Since the SSC300's core technology is based on magnetometers, the Heading
Sensor Reference (field 5) is always set to magnetic.
Field 1: SID – The sequence identifier field is used to tie related PGNs together. For example,
the SSC300 will transmit identical SIDs for Vessel Heading (PGN 127250), Attitude
(127257), and Rate of Turn (127251) to indicate that the readings are linked together
(i.e., the data from each PGN was taken at the same time although they are reported
at slightly different times).
2: Heading Sensor Reading – This field is used to report the vessel's heading and
includes deviation assuming a deviation table has been successfully loaded through
the magnetic deviation calibration process.
3: Deviation – The deviation is included in field 2, therefore this field always reads as 0.
4: Variation – The SSC300 does not use this field so the field is transmitted with the value
0x7FFF (data not available). See PGN 127258 for information regarding the SSC300
and its ability to transmit magnetic variation.
5: Heading Sensor Reference – The SSC300 transmits a "1" in this field to indicate that
the heading is referenced to magnetic North
6: Reserved – This field is reserved by NMEA; therefore, the SSC300 sets all bits to a
logic 1.
PGN 127251 – Rate of Turn
The SSC300 uses this PGN to indicate the vessel's rate of turn.
Field 1: SID – The sequence identifier field is used to tie related PGNs together. For example,
the SSC300 will transmit identical SIDs for Vessel Heading (PGN 127250), Attitude
(127257), and Rate of Turn (127251) to indicate that the readings are linked together
(i.e., the data from each PGN was taken at the same time although they are reported
at slightly different times).
2: Rate of Turn – This field is used to report the vessel's rate of turn.
3: Reserved – This field is reserved by NMEA; therefore, the SSC300 sets all bits to a
logic 1.
PGN 127257 – Attitude
The SSC300 uses this PGN to indicate the vessel's attitude (pitch and roll). The Yaw (field 2) is
not used, therefore this field always contains 0x7FFF (data not available).
Field 1: SID – The sequence identifier field is used to tie related PGNs together. For example,
the SSC300 will transmit identical SIDs for Vessel Heading (PGN 127250), Attitude
(127257), and Rate of Turn (127251) to indicate that the readings are linked together
(i.e., the data from each PGN was taken at the same time although they are reported
at slightly different times).
Revision 1.0
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Periodic Data Transmitted PGNs
Appendix B – NMEA 2000
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Interfacing
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Interfacing Page B1