Building a marine NMEA 2000 and NMEA 0183 network involves understanding the differences between these two standards and the specific requirements for each to ensure proper communication between marine electronics on a boat.
### **NMEA 0183 vs. NMEA 2000 Overview**
– **NMEA 0183**: An older, serial communication standard that uses a simple, single-talker, multiple-listener configuration. It’s generally slower (4.8 kbps) and uses ASCII text-based communication.
– **NMEA 2000 (N2K)**: A newer standard that supports faster data rates (250 kbps) and more devices with a multi-talker, multi-listener network, allowing more sophisticated communication between devices. It uses a Controller Area Network (CAN) protocol and has plug-and-play functionality.
### **Building an NMEA 0183 Network**
1. **Plan the Layout:**
– Identify the devices you want to connect (e.g., GPS, VHF radio, depth sounder, etc.). Understand which devices are talkers (output) and which are listeners (input).
– Determine the data sentences each device uses and ensure compatibility. You might need to use a multiplexer if you have more than one talker.
2. **Wiring:**
– NMEA 0183 typically uses two wires for data transmission: **A** (positive) and **B** (negative).
– Use shielded twisted-pair cables for connections to minimize interference.
– Connect the talker’s **A (TX+)** to the listener’s **A (RX+)** and the talker’s **B (TX-)** to the listener’s **B (RX-)**.
– Power the devices according to the manufacturer’s instructions, ensuring all are grounded properly.
3. **Testing:**
– Test the network after installation to ensure communication is working correctly between the devices.
### **Building an NMEA 2000 (N2K) Network**
1. **Plan the Layout:**
– List all NMEA 2000-compatible devices (e.g., chartplotter, autopilot, engine interface) and decide where to place the network backbone.
– The NMEA 2000 network is typically built around a backbone cable with multiple connections (T-connectors).
2. **Components Needed:**
– **Backbone cable**: The main communication line.
– **T-connectors**: For connecting each device to the backbone.
– **Drop cables**: Short cables to connect devices to the T-connectors.
– **Terminating resistors**: Two 120-ohm resistors required at each end of the backbone.
– **Power tap**: Supplies power to the NMEA 2000 network (usually 12V).
3. **Install the Backbone:**
– Run the backbone cable through the boat, keeping it as short as possible while reaching all devices.
– Attach T-connectors to the backbone where devices will connect.
– Ensure you have terminators at both ends of the backbone for proper communication.
4. **Connecting Devices:**
– Use drop cables to connect each NMEA 2000 device to a T-connector on the backbone.
– Only one power tap should be used for the entire network. It can be inserted anywhere along the backbone.
5. **Testing and Troubleshooting:**
– Once all devices are connected, power on the network and check each device for communication status.
– Use a diagnostic tool or check the device’s displays to confirm proper network functionality.
**Integrating NMEA 0183 with NMEA 2000**
1. **Use a Gateway Converter:**
– If you have a mix of NMEA 0183 and NMEA 2000 devices, use an NMEA 0183 to NMEA 2000 gateway. This device converts signals between the two standards.
2. **Connect the Gateway:**
– Connect the NMEA 0183 devices to the gateway using their respective A and B wires.
– Connect the gateway to the NMEA 2000 network via a T-connector.
**Best Practices**
– **Keep it Simple**: Use the shortest cable lengths possible to reduce signal degradation.
– **Avoid Interference**: Run network cables away from high-power electrical lines and sources of interference.
– **Waterproofing**: Ensure all connectors and cables are waterproof, and use marine-grade components to prevent corrosion. Shrink wrap all electrical connections.
– **Label Cables**: Clearly label cables and connections to help with future troubleshooting and maintenance.
When in doubt use or consult with a NMEA/MEI CERTIFIED INSTALLER!
