Glossary of Terms

NMEA: National Marine Electronics Association

NMEA 2000: NMEA Specified CAN Bus system, allowing all onboard NMEA 2000 electronics to communicate seamlessly, all connected to one network. Designed as a multi-talker, multi-listener serial data network, with data priority.

NMEA 0183: NMEA standardized format, which operates on both RS-232 and RS-422 serial comms, depending on which variant of NMEA 0183 the device uses.

OneNet: third-generation NMEA standard for marine data interfacing and network, operating on Ethernet. It has the power to bridge all three NMEA Standards together into a combined data network. OneNet is an open industry standard, based on the power of Internet Protocol v6 (IPv6).

IPv6: Internet Protocol Version 6 is the latest Internet Protocol Standard, acting as the latest standard to accommodate for the lack of available IPv4 addresses.

J1939: a communication protocol primarily used in the heavy-duty vehicle and marine industries. It is a CAN-based protocol that provides a standardised way for electronic devices to communicate with each other over a network.

CAN Bus: Controller Area Network Bus is a widely used communication protocol in the automotive and industrial automation industries. It is a network technology that allows various electronic devices and sensors to communicate with each other efficiently.

PGN: a Parameter Group Number is a unique numerical identifier used to categorise and define specific sets of data within the NMEA 2000 and J1939 communication protocols. PGNs contain every piece of NMEA 2000 data available.

Ethernet: the typical method used for creating wired networks, either LAN (local area network) or WAN (wide area network).

Backbone cable: main cable that connects all the devices in the network. It is the core of an NMEA 2000 network, whereby it should be rated for marine use and be of a suitable length to reach all devices on the boat whilst still conforming to NMEA 2000 and DeviceNet specifications.

Drop cable: this cable connects devices to the backbone and should be run from the backbone to each device location. A maximum of 6m is allowed for a drop cable.

Termination resistors: these resistors are installed at each end of the backbone cable to prevent signal reflections and ensure smooth communication between devices. Termination resistors are essential to ensure that the network functions correctly.

Power supply: this connection provides power to the network. The power supply should be rated for marine use and have enough power to supply all devices on the boat

Transducer: a transducer is an electrical sensor device that is used to measure depth. Some come with temperature sensors to measure the temperature of the water. There are several different types of transducers, and an array of suitable materials, depending on the material of the Hull.

Buffer: A buffer is designed to distribute data from one or two talker devices to multiple connected listeners. Buffers are typically low inputs, high outputs.

Multiplexer: A multiplexer or combiner is designed to collate the data from multiple inputs and output it via a low number of outputs. Multiplexers are typically high inputs, low outputs.

DST: Depth, speed, temperature transducer

Sensors and instruments: These devices collect various types of data, such as temperature, depth, and speed, and transmit the data across the network. Some common sensors and instruments include GPS receivers, depth sounders, and weather stations.

Display devices: These devices receive data from the network and display it in a user-friendly format, such as on a chartplotter or instrument display. Chartplotters are particularly useful for displaying navigational data, while instrument displays can be used to monitor the status of various systems on board.

AIS: stands for Automatic Identification System. This tracking system utilises AIS transceivers aboard ships, and the information from AIS is used in many scenarios, from leisure craft and surveyors, through to commercial vessels and coast guards. In simple terms, AIS is a collision avoidance system.

VHF: Very High Frequency radios which allow communication between boats. Channel 16 Mayday alerts are sent out via VHF.

DSC: stands for Digital Selective Calling and is a standard method of transmitting messages via VHF. Its primary use is for sending distress calls to both other vessels and shore systems.

MFD: multi-function displays are common devices and have the capability to display vast amounts of data

Radar: is a shortened term for Radio Detection and Ranging. They detect surrounding objects by transmitting RF energy and receiving small energy reflections off them.

GPS: stands for Global Positioning System. It is a satellite-based radio navigation system (RNSS) and is one of the Global Navigation Satellite Systems (GNSS)

GNSS: Global Navigation Satellite System is a combination of several Satellite position systems.

Data-logging: the capability to log important onboard data such as voyage data

Autoswitch: The autoswitch feature is designed to improve the reliability of navigation data, and act as a safety net. The idea of autoswitch is to have a primary and a secondary instrument (i.e. 2 GPS’ onboard). The device will listen to the primary GPS until it is turned off or fails, at which point it will switch to the secondary GPS input. The device will switch back once the primary input signal returns.

Ground loop: a ground loop exists when two or more paths to the ground connection of the ship’s DC battery supply are created

Isolation: prevents the two biggest issues plaguing DC power systems and the devices on them; ground loops and ground potential differences

ISO-Drive: Proudly engineered by Actisense, ISO-Drive™ technology is unique to our products and ensures each ‘Talker’ output is protected. ISO-Drive™ provides an isolated output, making installation simple and free from ground loops. This substantially reduces the risk of damage and hazards in connected equipment.

RINA Type Approval: “Type approval is a procedure for the approval of the product design, including drawing appraisal and prototype test performance, for compliance with classification or Flag Administration requirements. It basically implies that the design of the product is assessed once, and the approval is made valid for all subsequent products of identical design.”

Glossary of Terms

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