Build an NMEA 2000 network – Everything you need to know for a safe installation

Learn what NMEA 2000 is, the benefits of the standard, the minimum network requirements, and how to test and diagnose your installation.

Who are NMEA?
NMEA stands for National Marine Electronics Association, a non-profit organization working to improve data communication between manufacturers of marine electronics. Read more at www.nmea.org.

What is NMEA 2000?

NMEA 2000 is a standard developed by NMEA to create a unified system for communication between marine devices. It makes installation easy and allows different instruments to share data. Note that "open standard" means it is available for purchase at a reasonable cost, not free.

For best results, you should use NMEA 2000-certified devices that meet all requirements and are fully tested.

Benefits of NMEA 2000

• Easy "plug and play" installation.
• Reliable network that is self-configuring – no restarts required when adding devices.
• Support for up to 50 compatible devices on the same network.
• Ability to retain NMEA 0183 devices by using a gateway such as Actisense NGW-1.

Minimum requirements for an NMEA 2000 network

1. A fused power insertion point, e.g., Actisense A2K-MPT-2.
2. NMEA 2000-certified devices, cables, and connectors.
3. Two termination resistors (120 Ohm each).

Actisense Starter Kits contain everything you need to build a basic network.

Physical layer and backbone

NMEA 2000 uses the DeviceNet standard for cables and connectors, providing robust and waterproof connections. The backbone is the main cable where all devices connect via T-pieces. Each end of the backbone must be terminated with a 120 Ohm resistor for proper function.

Cable types

• Micro: For smaller installations and instrument drops.
• Mid: For larger backbone installations.
• Mini: For very large networks with high load.

The Actisense A2K series offers pre-cut cable lengths and bulk cable for custom installations.

Connections

All NMEA 2000 connectors follow the DeviceNet standard with screw couplings for easy and secure installation. Actisense offers T-pieces, four-way pieces, and field-attachable connectors for flexible solutions.

Power supply

Power can be supplied via A2K-MPT-2, A2K-SBN, or QNB-1. These solutions provide secure power distribution and isolation for the network.

Common terms

• Backbone: The main cable to which all devices are connected.
• Drop Cable: The cable connecting a device to the backbone (max 6 m).
• PGN: Parameter Group Number – messages used for data sharing.

How to test and diagnose the network?

Check voltage at the insertion point and network ends (should be between 9V and 14V). Also, check that the network has correct termination resistance (60 Ohm total). If there are problems, divide the network into sections and test incrementally.

Watch the Actisense instructional video

Summary

NMEA 2000 provides a robust, simple, and scalable network for marine devices. Use certified products, correct cabling, and follow the standard's guidelines for a safe installation.