Nmea 2000 Network Troubleshooting - Dometic Seastar DCM User's Manual And Troubleshooting Manual

Troubleshooting Guide
4 .2 NMEA 2000
Network Troubleshooting
• Usually troubleshooting requires nothing more than a few
basic tools and knowledge of what a proper NMEA 2000
backbone construction should consist of. Given the tools
and knowledge, troubleshooting could be considered easy,
as all the parts are "Plug and play." Usually technicians use
the process of elimination to find and eliminate problems.
This method is recommended at times however, may not
always work swiftly if there is more than one piece of faulty
equipment on the network.
• It is recommended to take a NMEA cable and cut the female
end off of the cable, strip back the conductors from the
remaining male cable and terminate them onto a terminal
strip as shown in figure 3-1.
This simple tool will plug into any open position on the
network allowing for easy ability to meter different parts of
the network.
• If there is a problem with a NMEA 2000 network, it is
recommended to start by removing network devices one at
a time. If the network works properly immediately after
removing a device, t is safe to assume there may be a
problem with the device or the associated network drop
cable. If this method does not resolve the network
problems the next step would be to test the network by
metering.
When Metering a
NMEA 2000 network
The resistance between Net-H (White) and Net-L (Blue) should
be approx. 60 Ohms with the network power turned off.
If this parameter is not met:
• Verify proper construction of NMEA network while
checking for loose connections
• Replace terminating resistors
• If value is still incorrect: Remove all devices from network,
check value again, determine faulty network "T"s , cables or
network power isolators by using process of elimination.
Replace necessary items effecting the network backbone.
With network power on the network voltage (Red & Black
should not be below 11V or Above 15V If this parameter is not
met:
• Charge system batteries
• Check charging system for proper voltage output
• Verify proper construction of NMEA network while
checking for loose connections
• Replace power insertion "T"
16
• If value is still incorrect: Remove all devices from network,
check value again, determine faulty network "T"s , cables or
network power isolators by using process of elimination.
Replace necessary items effecting the network backbone.
The shield and DC (-) conductor should have continuity
Although it is possible NMEA networks can be effected by
interference it is unlikely.
This rule exists for purposes to shield the network from
interference.
If this parameter is not met:
• Check power insertion point for proper connection, where
the shield is connected to DC (-).
Figure 4.1
EN