PGN reference

An NMEA 2000 message is identified by its PGN, its Parameter Group Number. The PGN says what the message is — 128267 is Water Depth, 129029 is a GNSS position — and every device on the bus broadcasts a handful of them.

This chapter lists every PGN this daemon decodes, every one it transmits, and how the multi-frame protocol works underneath. It is reference material for someone reading a candump capture or writing a compatible device; nothing here is needed to use the system.

Names below are the ones the decoders use.

Protocol PGNs

These carry the network itself rather than boat data. They are handled in the dispatcher and the address claim core.

PGN	Hex	Name	TX	RX
59392	0xE800	ISO Acknowledgment	yes	yes
59904	0xEA00	ISO Request	yes	yes
60928	0xEE00	Address Claimed	yes	yes
65240	0xFED8	Commanded Address		yes
126208	0x1ED00	Request / Command / Acknowledge Group Function	yes	yes
126464	0x1EE00	Transmit and Receive PGN Lists	yes	yes
126993	0x1F011	Heartbeat	yes
126996	0x1F014	Product Information	yes
126998	0x1F016	Configuration Information	yes

126208 is used in both directions: the daemon answers Request and Command group functions addressed to it, and transmits Command group functions to change a remote device's instance or one field of one of its PGNs — see Navigation.

The contents of 126996 and 126998 are set by the --nmea-version, --product-code, --model-id, --product-name, --serial-number, --cert-level, --load-equiv and --install-desc1 options. Defaults are in Reference.

Alerts

PGN	Hex	Name	TX	RX
126983	0x1F007	Alert	yes
126984	0x1F008	Alert Response		yes
126985	0x1F009	Alert Text	yes

126986, Alert Configuration, is defined but neither transmitted nor decoded. See Alarms.

Navigation and position

PGN	Hex	Name	Frames	Encoder
65267	0xFEF3	Vehicle Position (J1939)	single
65256	0xFEE8	Vehicle Direction/Speed (J1939)	single
129025	0x1F801	Position, Rapid Update	single	yes
129026	0x1F802	COG & SOG, Rapid Update	single	yes
129029	0x1F805	GNSS Position Data	fast	yes
129044	0x1F814	Datum	fast
129283	0x1F903	Cross Track Error	single	yes
129284	0x1F904	Navigation Data	fast	yes
129285	0x1F905	Route/WP Information	fast
129291	0x1F90B	Set & Drift, Rapid Update	single
130577	0x1FE11	Direction Data	fast	yes

Time and date

PGN	Hex	Name	Frames
126992	0x1F010	System Time	single
129033	0x1F809	Time & Date	single

GNSS and satellites

PGN	Hex	Name	Frames	Encoder
129539	0x1FA03	GNSS DOPs	single	yes
129540	0x1FA04	GNSS Satellites in View	fast	yes
129542	0x1FA06	GNSS Range Residuals	fast
129547	0x1FA0B	GNSS Pseudorange Error Statistics	fast

Steering and attitude

PGN	Hex	Name	Frames	Encoder
127237	0x1F105	Heading/Track Control	fast	yes
127245	0x1F10D	Rudder	single	yes
127250	0x1F112	Vessel Heading	single	yes
127251	0x1F113	Rate of Turn	single	yes
127257	0x1F119	Attitude	single	yes

Speed, depth and log

PGN	Hex	Name	Frames	Encoder
128000	0x1F400	Nautical Leeway Angle	single
128259	0x1F503	Speed, Water Referenced	single	yes
128267	0x1F50B	Water Depth	single	yes
128275	0x1F513	Distance Log	fast

Environment

PGN	Hex	Name	Frames	Encoder
127258	0x1F11A	Magnetic Variation	single
130306	0x1FD02	Wind Data	single	yes
130310	0x1FD06	Environmental Parameters	single	yes
130311	0x1FD07	Environmental Parameters (deprecated)	single
130312	0x1FD08	Temperature	single
130313	0x1FD09	Humidity	single
130314	0x1FD0A	Actual Pressure	single
130316	0x1FD0C	Temperature, Extended Range	single

Engine and transmission

PGN	Hex	Name	Frames	Encoder
127488	0x1F200	Engine Parameters, Rapid Update	single	yes
127489	0x1F201	Engine Parameters, Dynamic	fast	yes
127490	0x1F202	Engine Parameters, Static	fast
127493	0x1F205	Transmission Parameters, Dynamic	single	yes
127494	0x1F206	Transmission Parameters, Static	fast
127496	0x1F208	Trip Parameters, Vessel	fast	yes
127497	0x1F209	Trip Parameters, Engine	fast	yes
127498	0x1F20A	Engine Parameters, Static	fast
130576	0x1FE30	Trim Tab Status	single	yes

J1939 engine PGNs

Some engines and gensets on a marine bus speak J1939 rather than NMEA 2000 for their own data. These are decoded too:

PGN	Hex	Name
61443	0xF003	Electronic Engine Controller 2 (EEC2)
61444	0xF004	Electronic Engine Controller 1 (EEC1)
61445	0xF005	Electronic Engine Controller 3 (EEC3)
65214	0xFEBE	Auxiliary I/O Status (AUXIO)
65242	0xFEDA	Software Identification (SOFT)
65253	0xFEE5	Engine Hours, Revolutions
65260	0xFEEC	Vehicle Identification Number (VIN)
65262	0xFEEE	Engine Temperature 1 (ET1)
65263	0xFEEF	Engine Fluid Level/Pressure 1 (EFLP1)
65266	0xFEF2	Fuel Economy, Liquid (LFE)
65270	0xFEF6	Inlet/Exhaust Conditions 1 (IC1)
65271	0xFEF7	Vehicle Electrical Power 1 (VEP1)
65272	0xFEF8	Transmission Fluids (TF)

Electrical

PGN	Hex	Name	Frames
127501	0x1F20D	Binary Switch Bank Status	single
127503	0x1F20F	AC Input Status	fast
127504	0x1F210	AC Output Status	fast
127505	0x1F211	Fluid Level	single
127506	0x1F212	DC Detailed Status	fast
127507	0x1F213	Charger Status	fast
127508	0x1F214	Battery Status	single
127509	0x1F215	Inverter Status	fast
127513	0x1F219	Battery Configuration Status	fast
127744	0x1F300	AC Power / Current, Phase A	single
127745	0x1F301	AC Power / Current, Phase B	single
127746	0x1F302	AC Power / Current, Phase C	single
127747	0x1F303	AC Voltage / Frequency, Phase A	single
127748	0x1F304	AC Voltage / Frequency, Phase B	single
127749	0x1F305	AC Voltage / Frequency, Phase C	single
127750	0x1F306	Converter Status	single
127751	0x1F307	DC Voltage / Current	single

AIS

PGN	Hex	Name	Frames	Encoder
129038	0x1F80E	AIS Class A Position Report	fast	yes
129039	0x1F80F	AIS Class B Position Report	fast	yes
129040	0x1F810	AIS Class B Extended Position Report	fast
129041	0x1F811	AIS Aids to Navigation Report	fast	yes
129793	0x1FB01	AIS UTC and Date Report	fast
129794	0x1FB02	AIS Class A Static and Voyage Related Data	fast	yes
129795	0x1FB03	AIS Addressed Binary Message	fast
129796	0x1FB04	AIS Acknowledge	fast
129797	0x1FB05	AIS Binary Broadcast Message	fast
129798	0x1FB06	AIS SAR Aircraft Position Report	fast	yes
129801	0x1FB09	AIS Addressed Safety Related Message	fast
129802	0x1FB0A	AIS Safety Related Broadcast Message	fast	yes
129809	0x1FB11	AIS Class B Static Data, Part A	fast	yes
129810	0x1FB12	AIS Class B Static Data, Part B	fast	yes
129812	0x1FB14	AIS Single Slot Binary Message	fast

The encoders exist because the simulator transmits realistic AIS traffic; the daemon itself does not transmit AIS on a boat.

DSC

PGN	Hex	Name	Frames
129808	0x1FB10	DSC Call Information	fast

Route and waypoint service

PGN	Hex	Name	Frames	Encoder
130064	0x1FC40	Route and WP Service — Database List	fast
130065	0x1FC41	Route and WP Service — Route List	fast
130066	0x1FC42	Route and WP Service — Route/WP-List Attributes	fast	yes
130067	0x1FC43	Route and WP Service — Route, WP Name & Position	fast	yes
130068	0x1FC44	Route and WP Service — Route, WP Name	fast
130069	0x1FC45	Route and WP Service — XTE Limit & Navigation Method	fast
130074	0x1FC4A	Route and WP Service — WP List, WP Name & Position	fast

Radar and target tracking

PGN	Hex	Name	Frames
128520	0x1F608	Tracked Target Data	fast
128521	0x1F609	Tracked Target Information	fast
128522	0x1F60A	Radar Guard Zone	fast
128523	0x1F60B	Radar Data Processing Status	fast
128524	0x1F60C	Radar Sweep Status	fast

Thrusters, windlass and watermaker

PGN	Hex	Name	Frames	Encoder
128006	0x1F406	Thruster Control Status	single	yes
128007	0x1F407	Thruster Information	single	yes
128008	0x1F408	Thruster Motor Status	single	yes
128777	0x1F709	Anchor Windlass Operating Status	single
128780	0x1F70C	Linear Actuator	single
130567	0x1FE07	Watermaker Input Setting and Status	fast
130568	0x1FE08	Watermaker Operating Status	fast
130569	0x1FE09	Watermaker Production Status	fast

Fast Packet

Single CAN frames carry 8 bytes. Anything longer uses NMEA 2000's Fast Packet protocol, which splits the message across consecutive frames of the same PGN.

Property	Value
Maximum payload	223 bytes
Reassembly timeout	750 ms
Frame counter	first byte, bits 0–4
Sequence counter	first byte, bits 5–7
Timeout check interval	100 ms

The first frame carries the sequence and frame counters, the total byte count and the first 6 payload bytes; every subsequent frame carries the counters and 7 more bytes. The 3-bit sequence counter lets two Fast Packet messages of the same PGN interleave without being confused for one another, and the reassembler keys its sessions on it.

An incomplete message is dropped when the 750 ms timer expires. The daemon counts completed, dropped and processed frames and prints the totals at shutdown:

Fast Packet: Stats completed=1234 dropped=2 frames=9876

--fp-delay USEC sets the gap between transmitted Fast Packet frames, default 1000 µs. Some chartplotters lose frames sent back to back.

The Linux kernel's J1939 stack may reassemble a Fast Packet itself, in which case the whole payload arrives in a single read and bypasses the reassembler entirely. Both paths end in the same handler.

--pgn-list-fp-only restricts the transmitted PGN List (126464) to what fits in one Fast Packet message — 74 PGNs — rather than using ISO transport for a longer list. It is a compatibility workaround for plotters that cannot read the longer form.

Proprietary PGNs

NMEA 2000 reserves four ranges for manufacturer-specific messages. The first two bytes of the payload carry an 11-bit manufacturer code and a 3-bit industry group; the rest is manufacturer-defined.

Range	Hex	Frames	Addressing
61184–61439	0xEF00–0xEFFF	single	destination-specific
65280–65535	0xFF00–0xFFFF	single	broadcast
126720–126975	0x1EF00–0x1EFFF	fast	destination-specific
130816–131071	0x1FF00–0x1FFFF	fast	broadcast

An unrecognised proprietary PGN is logged and ignored; it never produces an error. --verbose-pgn-proprietary logs them with their manufacturer code and payload, which is the starting point for adding support for a new one.

Supported proprietary PGNs

Manufacturer	Code	PGN	Hex	Name	Frames
Cyclops Marine	641	65293	0xFF0D	Load Data	single

Unknown PGNs

A PGN with no decoder is logged with its number, source address and payload length, and otherwise ignored. That is deliberate: a marine bus carries traffic from equipment this daemon has never heard of, and a gateway that treated the unknown as an error would be useless.

Name tables

Three JSON tables ship with the package and are loaded at startup from --data-dir:

File	Content
manufacturers.json	NMEA manufacturer code to name
functionNames.json	J1939 function code to name
pgn.json	PGN number to name

pgn.json has a standard array of { "pgn": …, "name": … } and an empty proprietary object reserved for manufacturer-specific definitions.

A missing or unreadable table is not fatal: the daemon logs the failure and reports numeric codes instead of names.

Standards

PGN numbers, their field layouts and the Fast Packet protocol are defined by NMEA 2000 (IEC 61162-3). The 6xxxx-range PGNs and the NAME and address-claim machinery come from SAE J1939. Neither standard is reproduced here; MUXEN's copies are third-party material and are not part of this manual.