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NMEA-2000 Parameter Groups

by James W. Hebert

An overview is presented of NMEA-2000 parameter groups, currently limited to two groups which contain engine data, one group for navigation data, and three groups which contain vessel heading and attitude data. This information has been collected from publicly-available sources.

The NMEA-2000 Protocol

Detailed information about the NMEA-2000 protocol is difficult to obtain without purchasing expensive documents, which then require a non-disclosure agreement. The information below has been obtained from published information about NMEA-2000 parameter groups, and does not come from any sources which are restricted by non-disclosure agreements. I have collected the information from a variety of sources on the internet, and I simply aggregate it here for convenience.

In the NMEA-2000 protocol data is encapsulated into datagrams called parameter groups. The parameter groups are identified by number, and typically referred to by their parameter group number or PGN. In order to clearly specify the capabilities of a particular device, more and more manufacturers of NMEA-2000 devices are now including a NMEA-2000 PGN list to define what data their devices can receive from or send to the network.

Many modern outboard engines are certified for connection to NMEA-2000 networks. These modern engines transmit data about themselves to the network, where the data can be received by a variety of devices, processed, and displayed to an operator. An engine with NMEA-2000 certification will send data to the network. Once the data is on the network, there can be multiple devices listening for this data, and the same data can be displayed on several instruments or screens and in multiple places. The data can even be ingested and logged by a data logger. In the beginning of NMEA-2000 there were a limited number of engines which provided a NMEA-2000 port, and it was typical that the engine manufacturer would also provide the instrumentation to receive the data from the network. As the NMEA-2000 protocol became more popular, a variety of manufacturers began to produce NMEA-2000 instruments which could receive engine data from a network, and it is now common that data from an engine will be received and displayed on a device made by another manufacturer.

Engine Data in NMEA-2000

For engine data there are two parameter groups which provide data, PGN 127488 and PGN 127489. We now look at these PGN's in detail.

PGN 127488: Engine Parameters, Rapid Update

PGN 127488 provides data with a high update rate--ten times per second--about a limited number of engine parameters which are liable to rapidly change.

PGN 127488
Engine ParameterTypical Display Range
Engine Speed0 - 10,000 RPM
Boost Pressure0 - 400 PSI
Tilt-Trim Position0 - 100 %

Field Details

PGN 127489: Engine Parameters, Dynamic

PGN 127489 carries data about a wide range of engine parameters with an update rate of once per second.

PGN 127489
Engine ParameterTypical Display Range
Oil Pressure0 - 400 PSI
Oil Temperature0 - 500 ° F
Temperature0 - 500 ° F
Alternator Volts0 - 100 Volts
Fuel Rate0 - 800 GPH
Total Hours0 - 999999
Coolant Pressure0 - 400 PSI
Fuel Pressure0 - 400 PSI
Check Engine0 - 1 (OFF-ON)
Over Temp0 - 1 (OFF-ON)
Low Oil Pressure0 - 1 (OFF-ON)
Low Oil Level0 - 1 (OFF-ON)
Low Fuel Pressure0 - 1 (OFF-ON)
Low System Voltage0 - 1 (OFF-ON)
Coolant Level0 - 1 (OFF-ON)
Water Flow0 - 1 (OFF-ON)
Water In Fuel0 - 1 (OFF-ON)
Charge Indicator0 - 1 (OFF-ON)
Preheat Indicator0 - 1 (OFF-ON)
High Boost Pressure0 - 1 (OFF-ON)
Rev Limit Exceeded0 - 1 (OFF-ON)
EGR System0 - 1 (OFF-ON)
Throttle Position Sensor0 - 1 (OFF-ON)
Emergency Stop Mode0 - 1 (OFF-ON)
Warning Level 10 - 1 (OFF-ON)
Warning Level 20 - 1 (OFF-ON)
Power Reduction0 - 1 (OFF-ON)
Maintenance Needed0 - 1 (OFF-ON)
Comm Error0 - 1 (OFF-ON)
Sub or Secondary Throttle0 - 1 (OFF-ON)
Engine Shutting Down0 - 1 (OFF-ON)
Engine ParameterTypical Display Range
Percent Load0 - 100 %
Percent Torque0 - 124 %

Field Details

Navigation Data in NMEA-2000

Navigation data in NMEA-2000 is sent in 43 different parameter groups. One PGN is documented here.

PGN 129026: COG and SOG, Rapid Update

PGN 129026 provides data about the vessel speed over ground and course over ground with rapid update. The designator rapid update refers to the frequency of this PGN being sent. A typical frequency is four times per second (4-Hz).

PGN 129026
Vessel Heading
Sequence ID
COG Reference
Reserved (6 bits)
Course Over Ground
Speed Over Ground

Field Details

Vessel Heading and Attitude Data

Information about vessel heading and attitude is sent in three parameter groups. Only a limited detail is available about these PGN datagrams.

PGN 127250: Vessel Heading

PGN 127250 provides data about the vessel heading from a heading sensor.

PGN 127250
Vessel Heading
Sequence ID
Heading Sensor Reading
Heading Sensor Reference

Field Details

PGN 127251: Rate of Turn

PGN 127251 provides data about the vessel rate of turn, the rate at which the vessel heading is changing.

PGN 127251
Rate of Turn
Sequence ID
Rate of Turn

Field Details

PGN 127571: Attitude

PGN 127257 provides data about the vessel attitude, the position of the vessel relative to the horizontal and vertical planes.

PGN 127257
Sequence ID

Field Details

PGN 127505: Fluid Levels

PGN 127505 provides data about the fluid levels in tanks.

PGN 127505
Fluid Levels
Fluid Instance
Fluid Type
Fluid Level
Tank Capacity

Field Details

DISCLAIMER: This information is believed to be accurate but there is no guarantee. We do our best!

Copyright © 2012 by James W. Hebert. Unauthorized reproduction prohibited!

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