Actisense NMEA 2000 cables and connectors and network design tips (2023)

If you need a small NMEA 2000 network, the Actisense all-in-one 4-way device above left is a particularly simple and robust solution. In fact, it includes all of the components seen in the starter kit to the right, and the resulting network is slightly better in that it offers four N2K sockets for drop cables to devices like plotters and sensors, while one of the starter kit's four ports is occupied by the drop in performance.

On the other hand, theActisenseRIB-Starterkitis the better choice if the N2K network backbone ever needs to be expanded. You can simply run cables from one or both ends of the 4-way cable and move one or both backbone terminators to the new end(s). The Terminators are now built into hers4-way network for small boatsmeans that the backbone cannot be expanded.

However, you can do a lot more with a short N2K backbone and drop cables than many people realise, and that's a small part of what I'll explain below. I've had fun emulating various network designs on my new test and photo bank and they will hopefully illustrate what you can and can't do within the NMEA 2000 standard, as well as some techniques that are simply good practice.

But let's start with what you can get away with...at least on a small NMEA 2000 network...and at least most of the time. I can't really remember when or why I put this funky 3-way backbone and power drop together, but I know it works well while exemplifying numerous bad practices. The terminators, for example, are from different manufacturers (although theyshouldoffer the same resistance), and I think that thin power drop wires can contain power wires that are even smaller than the 22 AWG that's normal with the N2K micro wiring that most boats use.

As I understand it, the key feature of reliable N2K wiring and connector designclean impedance in the data cables, which means consistently good connections and proper backbone termination. Second, there can't be a large voltage drop since the 12V DC is passed from the power drop cable to the far ends of the network. (And please ignore the wire nuts, which should never be seen on a boat.)

But for microcable networks, NMEA allows up to 50 devices on a backbone up to 100 meters (328 ft) long with numerous drop cables up to 6 m (20 ft) long (but no longer than 78 m or 256 ft). total branch length). This is a large network and I've been told that the NMEA has been conservative about what other standards allow for itDeviceNet Micro C "physical layer"(also called cables and connectors).

In short, you can go pretty crazy with small N2K networks and probably get away with it, and I did.

Additionally, a drop (aka spur) from an N2K backbone (aka trunk) can involve much more than a cable to a device. The maximum drop length of 6 m (20 feet) can be branched in a number of ways, and there are multiports specifically designed for this purpose, such as those from ActisenseA2K-4WD NMEA 2000 4-Way Instrument TrayorMaretrons Micro Multi Port. (Note that the latter multi is well made by Turck, and if you're frugal and adventurous, note that I've found an inexpensive yet industrial strengthTurck 8x multiport on eBaywhich still work fine on Gizmo).

But you can also use regular T-connectors to split a drop. So what you see above is an 8-port N2K network based on the very short backbone of the Actisense All-in-One but extended with a 0.5m Maretron cable and aActisense A2K-4WTusually used along a main line. All 8 ports are female, which is what you want gender specific since N2K device ports are always male (aka pins). And it meets the NMEA 2000 standard penalty as long as the five drops added are no longer than 5.5m, as I will illustrate.

So I've now added another 4-way tee to get a network with 12 female ports available, although they're all still dropped from the same tiny backbone. And I've added some real N2K devices to better discuss how the drop cable length calculations work. For example, the red Actisense NGT-1 ISO gateway drops from the small backbone via the device's 0.5m cable and 1.5m N2K cable for a total of 2m. Meanwhile, the gray Maretron USB100 gateway drops over the same 0.5m cable plus the two gray 2m cables for a total of 4.5m.

Bottom line: Each unit is well within the 6m micro-drop limit, even if you add a little for the tees in between, and the full 6.5m is a small dent in the overall 78m drop budget. Beyond that 9 more ports are available with additional maximum drop cables from 3.5m to 6m depending on where you start. Are you still there?

Maretron's free N2KBuilder PC software tool may be a wonderful way to document an N2K network and test factors such as correct cable length"Better than sliced ​​bread" since 2009. N2KBuilder works with any NMEA 2000 device and can also estimate total 12V power requirements and possible voltage drops, which is our next topic.

N2K-Power-Drops

In a way it's another example of N2K network funkiness you can get away with - notice how many different types of microcable I've used for the drops - but this ActisenseQNB-1 fast network blockFor years, the original 14-foot center console has served well in the harsh electrical environmentGizmo,and also on a boat I loaned it to (hence the mysterious tape label I think). But here I would like to point out the two blade fuses as an introduction to the intricacies of high-performance power drops. You see, the QNB offers split backbone power but no dual power entry points, and I suspect most readers have no idea what that means.

Iwrote first about N2K power taps(aka power drops) in 2009, and the best methods for working with the limitations of microcable 22-gauge power cords remain the same: Plug in the 12V power supply near the center of the network to power the power cord - / to minimize resistance history, and also split the tap so each side gets the full 4A max injection (and also because you might want the ability to depower half the network).

As robust and flexible as the Actisense QNB is - consider the choice of gland or micro C-port models, or you can mix and match your ownA2K PMW connectors— it has no separate power supply lines. You can feed the internal power terminal block with a heavy gauge wire fused at 8 or more amps and each side of the network will get 4 amps to power each device's N2K processor as well as any N2K powered sensors, but you can switch the sides not switch separately. It's subtle indeed, but potentially important for someone wanting to constantly keep part of an N2K network alive on a meager power budget.

Meanwhile, the two QPD Quick Power Drop models that IDiscussed along with other N2K network details in 2012, provide dual power entriesAndSplit feeds along with other QNB extras like reverse polarity and data activity LEDs as shown inActisense Power Feed-Leitfaden (PDF)partially seen above. However, the QPD has been discontinued, even though it existsmany still in the supply chainand this isn't the kind of product where you have to worry about updates.

But how about this simple yet fully split oneA2K-MPT-1 Micro Power T-Stück? It will certainly get the job done, but it also introduces a particularly subtle N2K gender issue.

The Actisense Power Drop Tee is very similarThe bright yellow Micro/Mid PowerTap Tee by MaretronExcept one thing. While the Actisense tee is like a regular N2K tee - leaving a female and male connector free once the device or power drop is plugged in - the Maretron power tee has two female connectors.

The idea - which isn't mentioned in the NMEA 2000 standard - is that on a network where all connectors point to power, hot power connections are never exposed to potential problems. You can see the gender symmetry in the chart I found atold but golden DIY site, and while again this is subtly good practice, why not when the cost and effort are virtually nil?

And in the virtuoso Actisense/Maretron tennis game of high-performance N2K network hardware, it's the former that makes gender reassignment fairly easy.

gender change

Actisense offeredA2K-GC Lite Gender-Changer-Kabelfor quite a while, although it's only recently that I've had hands-on experience. As with all of their N2K networking hardware and Maretron's, the quality is excellent. But I dare say that those humble little cables did indeed evoke shouts of hallelujah. on certain occasions, like when a boot-crushed installer discovers that the ongoing N2K trunk extension is gendered.

And here's another way a sex change cable can come in handy. The black female-to-female swappable cable on the left turns a standard Actisense 4-way and single power cable into a Maretron-like gender-secured cable with all connector pins pointing to the 12V supply. Of course, field-installable N2K connectors are another way to solve gender issues, albeit not as easily.

Field installable connectors

Actisense also sent me a complete set of their male/female straight/rectangular onesA2K Field Fit connectorscheck over. It's no surprise that they're well designed and made, but there are important subtleties in this area too, and I have a slight fondness forMaretron's micro/mid field attachments.

More precisely, I warn against itAmphenol LTW Field installableSee connections below above and I hope the photo shows why. After running a bare N2K micro cable through the various sealing and strain relief bits on the left - all quite functional - there comes a moment when you need to fish five thin, stripped wires in five specific places, and good routing helps really.

In my view, Maretron is the winner with color-coded and detailed labels, Actisense is a close second with deeply engraved black-versus-gold numbers that hold the key to the pinout diagram in the box, and...well, I've tried Revealing it The pin numbers are embossed on the black plastic amphenol in this carefully lit close-up, but you might want a serious magnifying glass at work.

To be honest, I try to avoid using field attachables because of the extra work and occasional bugs I've experienced (possibly due to my own impatient work), but I know they're very useful for some installations. And there are subtle differences.

I hope this has been an uplifting discussion of NMEA 2000 micro networking, which is now a critical component on almost every new or refurbished recreational boat. Actisense and Maretron certainly aren't the cheapest sources, but is this an area where going cheap makes sense?

I'm closing with the last network I put together on my project bank before I go on vacation at the end of March. It's a more standard design than what you saw above and you only see part of it because the black wire on the top right is the backbone going to the base system of the lab and the power drop. But, hallelujah, all components shown are a demo kit of a powerful yet affordable Maretron MPower digital shifting system that is slowly coming to market.

As hoped, MPower is much like thatOctoplex Octolite shown at MIBS2018, but it is fully integrated with current Maretron surveillance equipment - even without the high-end N2KView - and will eventually be available to small builders and knowledgeable DIYers via the normal Maretron channels. More to come, and I look forward to the official release of Actisense as wellW2K-1 NMEA 2000 to WiFiModule that was impressively demonstrated at METS.