Troubleshooting NMEA 2000 Systems on Boats

Hello,

I recently have had several vessels I have surveyed with issues with their digital gauges freezing or not responding which turned out to be issues within the NMEA 2000 backbone or gauges (corrupted digital data). Many boat owners do not really understand how these systems work, how they communicate with each other, and are sometimes mislead by others in believing the engine or batteries are the problem when it is infact typically a corrupted "T" fitting, gauge, or terminator. I recently wrote a blog explaining how these systems work and how simple they are in troubleshooting them. These systems are the future of boats and more and more vessels being built are outfitted with these digital data systems. The blog is at:

https://suenosazulesmarinesurveying...shooting-nema-2000-systems-in-marine-engines/

I hope it helps everyone understand how they work and how easy it is to troubleshoot them.

 

NMEA 2000 is a joke.
No one professional are really taking it serious. it's hard to read out data and make use of it + the bus are sensitive to distances witch is a real pain on large bridges where you need to communicate with systems spread on the whole bridge. The old NMEA standard will survive until they come up with something better than 2000. Going to be something that will be on hobby vessels only.
Sorry for my rant, but I cant let anyone get away with saying it's the future without some resistance.

 

G'day Suenos,
Interesting link.
"The system runs off a high / low voltage system (low is 1.5 – 2.5 volts and high is 2.5 – 3.5 volts). The two voltages on the high / low mirror each other to confirm accurate data to the ECM. "
Complementary differential signals.

And ground is reference.

In light of what I have just experienced the maintenance of electrical isolation between CanL & Can H & ground is critical.
Any insulation break down could potentially lead to corruption, in my case M ohms.
Thankyou.

 

For those of us limited to a multi-meter are there any simple tests we can undertake that might detect faulty components?

I found a faulty T-connector in my NMEA system by removing 1 T-connector at a time and checking for improvement. But that's a slow and laborious process.

 

How do I check the health of my NMEA 2000 cabling before powering my network? https://www.maretron.com/support/knowledgebase/phpkbv7/article.php?id=443

 

Thanks. Is there a mistake in Step (5) on that page?

Step (5) refers to both Pin 4 and Pin 5 having a blue wire

Previous steps refer to Pin 4 having a white wire.