Specifications

location. Grounding at more than one location may
produce ground loops, which can cause problems with
communications on the network. In addition to the ground
wire, connect the drain or SHIELD wire at the supply ground
location and NO other place.
5. Checking Your Network
Verify that the network has been correctly designed and
installed by reviewing the following checklist:
Number of devices does not exceed 50•
Maximum Mini cable distance between any two •
devices does not exceed 200 meters (656 feet)
Maximum Micro/Mid cable distance between any two •
devices does not exceed 100 meters (328 feet)
Maximum cumulative drop line length does not exceed •
78 meters (256 feet)
No drop should be greater than 6 meters (20 feet)•
Termination resistors are installed on both ends of the •
trunk
The network is grounded at a single location•
The SHIELD wire is connected to a single point, the •
supply ground
If you are having difficulties with the network make sure to
check the following most common network problems:
More or less than two terminating resistors •
Loose connections, make sure that all connectors are •
securely fastened
Excessive trunk line length-especially with Micro cable •
Excessive drop line cable length •
Improper shield and ground connection at the •
power supply
Shorts and opens in field-attachable connectors •
Failure to perform power distribution calculations for •
new installations and when adding new devices
Using a typical device current rather than maximum •
current for power distribution calculations
In order to insure the proper installation and configuration of
an NMEA 2000® network, it is a good idea to have available at
least one N2KMeter. The N2KMeter greatly simplifies network
diagnostics and can detect many fault conditions including:
Opens and shorts•
Incorrect topology•
Bad nodes•
Bad termination•
Improper shield connection•
Intermittent problems•
Excessive scan rate•
Common mode voltage•
Figure 7
Middle-Powered Network
73
5 meters 20 meters 5 meters 0.3 meters 0.3 meters
Speed Log
0.3 meters
2 loads
TRTR
0.3 meter
2 loads
Depth Repeater
0.3 meter
2 loads
Compass Display
2 meters
1 load
Electronic Compass
Autopilot
1 meter
1 load
Power from
Battery
TR
Trunk Line
Drop Line
Device or Node
Drop Te e