NMEA 2000
NMEA 2000 is a type of network for data transmission that is mainly used in the shipping industry. In NMEA networks, data is transmitted between different navigation devices or several navigation devices are combined to form a network ( GPS , depth gauge, log , anemometer, compass, autopilot). It can also be used to transmit control and monitoring data from the ship's command (power generator, ship's engine, control, fire alarm, etc.).
history
NMEA 2000 was developed in 2000 by the NMEA standards organization as the successor to NMEA 0183 . NMEA 2000 is an extension of SAE J1939 , which is used in the commercial vehicle sector and is based on the Controller Area Network (CAN) developed by Bosch and Intel .
Features and configuration
NMEA 2000 is a network system (NMEA 0183 is only an interface and does not support network functions). Up to 50 devices can be integrated and simultaneously senders and receivers. They communicate at 250 kbit / s (50 times faster than NMEA 0183) over a distance of up to 200 meters. 100 data records can be transferred simultaneously. NMEA 2000 configures itself. Neither a setup nor a central control unit is required. The system differentiates between security-relevant data and ordinary data. Failed devices have no disruptive influence on the overall system.
Most devices that are equipped with a NMEA 2000 interface go through a standardized test process and are "NMEA 2000 certified".
interface
The devices are connected with a 4-core shielded cable. Two twisted wires are used for the power supply, two twisted wires transmit the data, the braided shield is the grounding. If more than two devices are connected, a "T-piece" is inserted at any point in the cable for each additional device and the device is connected to it. The free cable ends are terminated with a terminal resistor, which connects the two signal lines (121 Ω, 1%, 250 mW). The maximum distance between two T-pieces is 100 m, the maximum cable length between T-piece and device (branch cable) is 6 m.
The plugs are not standardized. Each manufacturer uses different plugs, and some even have different plugs for different devices. The plugs are connected to the cables in a waterproof manner and are mostly sold as complete cable sets, but loose MicroC plugs are available.
colour | Surname | tension | function |
---|---|---|---|
White | CAN_High | +2.5V | signal |
blue | CAN_Low | −2.5 V | signal |
metallic | earth | - | shielding |
red | V + | +12 V | Power supply |
black | V− | 0 V | Power supply |
- exam
- The network is correctly connected when the resistance between the two signal lines (white and blue) is between 50 and 60 ohms when the power supply is interrupted.
- Power supply
- The power supply usually only serves to supply display instruments and measuring instruments with low power consumption (anemometer, GPS, etc.). Larger electricity consumers are fed by their own power supply (chart plotter, depth gauge, autopilot, radar, etc.).
- Dimensions
- The cable system is usually not connected to the ship's earth so that insulation faults can be detected via an earth fault indicator before damage can occur in the power grid. The exception are smaller boats, where the neutral conductor is often connected to the hull directly at the power supply with a copper tape. If several power supplies are used, only one may be connected to ground; the 12 V line between the power supplies must then be interrupted.
Manufacturer
The most important manufacturers who use NMEA 2000 in their own devices are: Furuno , Garmin , Lowrance , Navico , Raymarine , Simrad and B&G . The largest cable suppliers are Maretron and Molex , connectors come from Turck and Amphenol-Air LB. Some manufacturers use their own connectors and are not NMEA 2000 certified. That is why the bus systems SimNet ( Simrad / Navico ) and SeaTalk NG ( Raymarine ) are called, but Simrad now also mainly uses the 5-pin MicroC connector that has become the de facto standard. With the appropriate adapter cables, however, they are largely compatible with NMEA 2000.
Group number parameter (PGN)
In the NMEA 2000 standard, data is assigned to a group number.
- Network management
PGN | Data |
---|---|
Acknowledgment basic | |
Acknowledgment group function | |
Address claim | |
Address, Commanded | |
Configuration information | |
Command group function | |
126996 | Product information |
Proprietary, Addressed | |
Proprietary, Global | |
126464 | Received PGN List Group Function |
059904 | Request, basic |
126208 | Request group function |
Transport Protocol, Connection Management | |
Transport Protocol, Data Transfer | |
126464 | Transmitted PGN List Group Function |
- Application Data
PGN | Data |
---|---|
127257 | Attitude |
129302 | Battery status |
129302 | Bearing and distance between two marks |
127501 | Binary Switch Bank Status |
129026 | COG & SOG, Rapid Update |
129283 | Cross track error |
130322 | Current station data |
date | |
129549 | DGNSS Corrections |
130577 | Direction data |
128275 | Distance log |
DSC call information | |
127489 | Engine parameters, dynamic |
127488 | Engine parameters, rapid update |
127497 | Engine parameters, static |
130311 | Environmental parameters |
127505 | Fluid level |
129556 | GLONASS Almanac Data |
129538 | GNSS control status |
129550 | GNSS Differential Correction Receiver Interface |
129551 | GNSS Differential Correction Receiver Signal |
129539 | GNSS DOPs |
129029 | GNSS position data |
129547 | GNSS pseudorange error statistics |
129542 | GNSS pseudorange noise statistics |
129545 | GNSS RAIM output |
129546 | GNSS RAIM Settings |
129540 | GNSS Sats in View |
129541 | GPS Almanac Data Heading / Track Control |
130053 | Loran-C Range Data |
130054 | Loran-C Signal Data |
130052 | Loran-C TD Data |
130323 | Meteorological Station Data |
130324 | Moored Buoy Station Data |
129284 | Navigation data |
129025 | Position, rapid update |
129799 | Radio Frequency / Mode / Power |
127245 | Rudder |
130321 | Salinity Station Data |
129291 | Set & Drift, Rapid Update |
130576 | Small craft status |
128259 | speed |
127502 | Switch bank control |
126992 | System time |
130320 | Tide Station Data |
126992 | Time & Date |
129301 | Time to / from Mark |
128520 | Tracked target data |
127493 | Transmission parameters, dynamic |
Trip parameters, small craft | |
129045 | User date settings |
127250 | Vessel heading |
130578 | Vessel Speed Components |
128267 | Water depth |
130306 | Wind data |
Web links
- NMEA 2000 on the NMEA website
- List of NMEA 2000 certified products ( Memento from January 13, 2013 in the web archive archive.today )
- NMEA 2000 parameters, with group numbers and summary ( Memento from January 13, 2013 in the web archive archive.today ) (English)
- Description of NMEA networks - NMEA.de
- DeviceNet cable installation manual ( Memento from April 23, 2015 in the Internet Archive ) (English; PDF; 22 MB)
- LA Luft, L. Anderson, F. Cassidy: NMEA 2000: A Digital Interface for the 21st Century . (English; PDF; 0.1 MB)