Pub. 988-0154-172 NMEA 2000 Networks General Information NMEA 2000 is a communication bus network specifically designed for boats. This is an industry standard developed by the National Marine Electronics Association(NMEA). To help you get the most out of this technology Lowrance has introduced a line of products that can communicate over a NMEA 2000 network. This instruction sheet outlines the basics of what it takes to create a NMEA 2000 network. It also will explain how to use this network to connect your Lowrance and LEI products and provide some tips on configuring and using the operational network. Setup and Installation of Terminology There are several key phrases you will need to know before we can explain how the NMEA 2000 system works. Some of these are technical terms, some of them are names taken from the NMEA 2000 standard and some of them are our own names developed for clarity. All of them will help you understand what we are saying. "NMEA 2000 Network" or "LowranceNET " When we talk about the NMEA 2000 network we are talking about the communications link between two or more devices that transfer NMEA 2000 information. "LowranceNET" is the NMEA 2000 networking system developed by Lowrance Electronics. Think of this as a computer network or the phone wiring in your house. If you pick up a phone in your living room you can hear someone talking into the phone in the bedroom. A NMEA 2000 network is a way to let more than one display unit "listen in" on the GPS antenna's conversation or to let more than one sonar display unit overhear the messages being sent by a temperature sensor. You can even view engine diagnostics and fuel level on digital gauges or display units located anywhere on your boat. If you have a Lowrance display unit with an LGC-2000 GPS module installed then you have a NMEA 2000 network. The connectors and cables that came with your LGC-2000 actually function as a dedicated 1 NMEA 2000 network passing GPS signal information along the network (that is, the extension cables) to the GPS display unit. This is a very limited application of the term "network." The other end of the scale is a network bus (described in the following segment) built into your boat with nodes at intervals allowing you to connect several GPS or sonar display units, temperature or water speed sensors, digital gauges or any other NMEA 2000 device. Such a network could display the temperature readings from two different sensors (one at the water surface and another in your live well) as well as the GPS signal from an LGC-2000 and even the reading from a fuel-flow sensor attached to your fuel line. The network could share all of this information with a sonar-GPS combo display unit mounted in the dash, a smaller sonar-only display unit at the stern and another up on the bow by your trolling motor. All three display units attached to the bus would have access to all of the sensor information from every accessory attached to the network. The network design would look like the one in the following diagram. Sonar unit at bow Sonar-GPS unit in dash LGC2000 EP-35 temp sensor in live well Sonar unit at stern 25' extension cable EP-10 fuel flow sensor EP-35 temp sensor at water surface NMEA 2000 network with three sonar or sonar-GPS combo display units, each receiving position information from the LGC-2000, temperature information from temp sensors at two different locations and fuel use information from a fuel flow sensor. 2 That is the advantage of a NMEA 2000 network. Every display unit, gauge or sensor attached to the network communicates with all the others. Of course location, speed and temperature are not the only kinds of information that can be shared. Other capabilities include the ability to share the amount of fuel remaining in your tanks, detailed engine information such as oil pressure and fuel efficiency and much more. NOTE: You probably noticed there is no transducer mentioned in that list or anywhere else in this document. The full sonar chart reading from a transducer takes too much bandwidth for a NMEA 2000 network which means sonar charts cannot be shared. Every sonar display unit requires its own transducer to draw charts. However, if you have a sonar display unit (with a working transducer) connected to the NMEA bus it will share the digital depth with every other display unit on the network. "NMEA 2000 Bus" or "Network Bus" Technically, any physical cable properly installed and used to transfer network information is a "network bus" but in our documentation we use this term to refer to the standard manufacturer installation appearing in new boats. This network bus is an installed and operational network cable running the length of your boat, already connected to a power supply and properly terminated. Such a bus provides network nodes at various locations around your boat. "Network Backbone" and "Network Nodes" A network bus is built of network nodes spread along a backbone. Network nodes are made by fitting T-shaped connectors into the backbone (using the sockets on the sides) and attaching a display unit or sensor at the bottom of the T. If we stick with the earlier example, the T connectors along the length of a boat are the equivalent of phone jacks spread throughout a house. Phones in a home have to be connected to each other to communicate and in the same way only sensors and display units plugged into the NMEA network can share information. The backbone is like the phone wiring that runs throughout a home; it connects these nodes. Connections found in the middle of the bus will have one or more of these T connectors with the backbone cables plugged into both sides. Connections at the end of a network will have the backbone plugged into one side and a terminator plugged into the other as shown in the following figure. 3 Cable from sensor or display unit LEI or Lowrance device needs an open T. Terminator at the very end of the bus Backbone cable (to rest of bus) NMEA 2000 network node located at the end of a NMEA 2000 backbone. All of the T connectors on your boat's network will probably be filled but if you want to add another node to a working network just add a T connector from LEI (ordering information appears on the back page of this booklet). If you are adding a Lowrance or LEI NMEA 2000 sensor it will come with its own T connector making the process even easier. This T connector allows you to add a device to your NMEA 2000 bus creating a network node. The "soft" T connector, shown above with a "hard" T connector, is another option for connecting devices in a NMEA 2000 network. The soft T works the same as a hard T. The soft T is used to install a network node in areas were a hard T will not fit. 4 "Linear Architecture" NMEA 2000 networks are designed using a linear architecture and it is important for you to maintain this pattern whenever you modify your network (such as adding nodes). When we say "linear architecture" we are referring to the way the network's backbone is assembled and to the way you attach T connectors along it. Note that every T connector has one female socket and two male sockets. This means you could connect it in two different ways. You could plug the sensor or display unit into the bottom of the T and the backbone cable into the side of the T (as we recommend). You could also plug the sensor or display unit into the side of the T and the backbone connection in the bottom of the T. The sockets would allow you to make that connection but you would lose linear architecture. Consider the following images. Sonar or GPS display unit Sonar or GPS display unit LGC2000 EP-35 temp sensor EP-35 temp sensor LGC2000 Correct architecture Incorrect architecture Two possible network designs. The design on the left maintains a linear architecture while the one on the right does not. You should always maintain linear architecture when building a NMEA 2000 network. Both of the network designs in these images contain the same set of components. Both networks are terminated and all of the connectors are able to attach together. However, the design on the left is easier to maintain and expand. It also allows you to make sure the two terminators are at the ends of the backbone. Since the system on the right is non-linear there is not a clear end. Always maintain linear architecture when modifying your network. Just make sure to attach display units or sensors to the bottom of the T. Attach the sides of the T to other T connectors, to backbone extension cables or to terminators ­ nothing else. 5 For reference purposes all of the example network designs you will find in this document show networks built with a linear architecture. Adding a Network Node You can add a node anywhere along the network backbone where a connection already exists. This connection could be at the end of the network (between a T connector and a terminator) between two T connectors, between a T connector and a backbone extension cable or between two extension cables. Wherever you want to add the new node simply separate the sockets of the old connection and attach your new T connector between them. Lowrance or LEI device connects to new T connector. Add T-shaped connector to add device to bus (maintaining linear architecture). Attach terminator at end of bus. Existing network node Add a new device to a NMEA 2000 bus by attaching a T connector between two T connectors, between a T connector and the end terminator, or between two backbone extension cables. If you want to add a node at the end of the line (as shown in the previous figure) remove the terminator from the very last connector, securely attach the new T connector, and attach the terminator on the new connector. Either method will allow you to add a device. NOTE: If your network only includes one terminator (such as the network created when a single display unit is connected to an LGC-2000) you will need to add a Node Kit before you can add additional network nodes. You only need to purchase a Node Kit once. After that you can add nodes as described in the previous section. Most manufacturer-installed networks will already have two terminators so a Node Kit will not be necessary. Adding an Extension Cable LEI provides LowranceNET extension cables in various lengths so that you can position all of the items on your network exactly where you want 6 them on your boat. Every extension cable has a male connector on one end and a female connector on the other allowing you to insert it anywhere the network has a connection. For instance, you might have a cluster of T connectors at the bow of your boat and attached to the last T on the cluster is a 15' extension cable running to your console. On the end of this extension cable you could have another cluster of T connectors and another extension cable running to the stern of the boat where you have more T connectors for more devices. We recommend you keep your network backbone to less than about 300 feet (100 meters). You can also attach an extension cable between a device on the network and the T connector allowing you to more easily position the device right where you want it. You should never use more than 15' (about 5 meters) of extension cable between a device and the network backbone. Building a LowranceNET NMEA 2000 Network In 2005, the original equipment manufacturers (OEM) began installing NMEA 2000 networks as standard equipment in new boats. If your boat does not have an OEM-installed NMEA 2000 network you will have to install your own. This instruction sheet will explain how to install a LowranceNET NMEA 2000 network using cables available from LEI. Installing a NMEA 2000 network is not complicated. If you can grasp a few essential concepts you can design a network to fit your needs and keep it running smoothly. Power In order for a NMEA 2000 network to operate the bus must be connected to a switched power source (a power source that you can turn on and off ­ generally a switch on your boat's accessory panel). NMEA 2000 networks require 12 volts DC power. If your boat came with a NMEA 2000 bus it should already be connected to a switched power source that draws from the boat's battery. To confirm how the bus was installed, consult your boat dealer or manufacturer. · No matter how large or small the network, no matter how many devices are sharing information along it, a NMEA 2000 network must be connected to a 12-volt power source to operate. If you are only running a display unit and an LGC-2000 on the mininetwork as described earlier you will still have to connect the display unit's NMEA 2000 Power cable to a switched power source in order to power the network. 7 · Always use a switched power source for your NMEA 2000 bus. Do not connect the NMEA 2000 Power cable directly to your boat's battery. You need to be able to turn the network's power on and off. Extension cable To network T connector Data cable ...