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.

Funky DIY 3-way N2K network with backbone to grow

But let's start with what you can get away 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.

Legal N2K network with 8 female ports and a 4T backbone

(Video) Everything you need to know about NMEA2000 | SVB

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.

A legal N2K network with 12 female ports available as long as the total length of the drop cable to a device is > 6m from the 4-way backbone

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.


This Actisense Quick Network Block with split and fused power feeds has worked and lasted a long time but lacks the dual power input

(Video) NMEA 2000 Network Guide Video

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.

Actisense NMEA 2000 Power Drop Guide

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.

Maretron power tap with shared backbone power, shared feed and two female connectors

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?

(Video) How To Fit A Field Connector NMEA2000 (I Got The Wind Vane Working) Sailing Meraki | Ep.30

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 N2K Gender Changer Cable, male and female

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.

Gender specific N2K backbone with gender change cable

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 N2K FFC-xx Field Fit Connectors – alle vier Typen

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.

(Video) Ethernet vs NMEA 2000 Network...How, When, and Why?

From top to bottom: Field-ready N2K connectors from Maretron, Actisense and LTW

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.

Maretron MPower DC demo kit ready for configuration and testing

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.


How do I troubleshoot my NMEA 2000 network? ›

One of the best ways to troubleshoot an N2K network is to use the following basic steps:
  1. Power down the NMEA 2000 network and all attached devices.
  2. Power up everything one at a time until the problem starts. Write down what you powered up and in what order. Usually the last device is the culprit.
Dec 15, 2019

What is the correct supply voltage for a NMEA 2000 network? ›

For the NMEA 2000 network to work properly there must not be more than a 1.67 Vdc drop in the supply voltage between the T-connector with the power cable and the NMEA 2000 device located farthest from this T-connector.

Are all NMEA 2000 cables the same? ›

There are three types of NMEA 2000® cabling systems, Micro, Mid and Mini. The Micro/Mid cable system is generally used for smaller networks requiring less power (i.e., less than 4 amps per network leg) while the Mini cable system is used for larger networks (i.e., more than 4 amps but less than 8 amps per leg).

How many devices can connect to NMEA 2000? ›

An NMEA 2000 network can have up to 50 physical devices connected to the network at any one time.

Where do I connect my NMEA 2000 power cable? ›

If you are installing a NMEA 2000 power cable, you must connect it to the boat ignition switch or through another in-line switch. NMEA 2000 devices will drain your battery if the NMEA 2000 power cable is connected to the battery directly.

How do I test my NMEA signal? ›

Termination check
  1. Switch-off the power to the NMEA 2000 network.
  2. Connect the test cable to the diagnostic T-connector next to the power insertion point.
  3. Using the multimeter, measure the voltage between the RED and BLACK wires. ...
  4. Measure the resistance between the WHITE and BLUE wires.

How do I know if my NMEA 2000 is working? ›

  • The reading should be close to 60 Ohms.
  • If the resistance reading is 120, only one terminator is connected to the network. ...
  • If the resistance reading is very high, there are no terminators on the network or a break in one of the network components.
  • If the reading is far less than 60, there is a short in the network.

How do I connect NMEA 2000 devices? ›

All NMEA 2000 devices must connect to the backbone via a T-Piece, this is known as an 'instrument drop'. Each end of the backbone must be correctly terminated with a 120 Ohm resistor. These resistors are connected in parallel and therefore provide 60 Ohms termination resistance over the entire network.

What is the maximum cable length for NMEA 2000? ›

The maximum length of an NMEA 2000 cable used to connect any device or accessory to a T-Connector is 20 feet (6 meters). If a 20 feet cable is not long enough to connect the device or accessory to the T-Connector, a longer NMEA 2000 backbone cable connects to the NMEA 2000 network's backbone.

How many amps does a NMEA 2000 use? ›

There are two sizes of cabling defined by the DeviceNet/NMEA 2000 standard. The larger of the two sizes is denoted as "Mini" (or alternatively, "Thick") cable, and is rated to carry up to 8 Amperes of power supply current.

How do I test my NMEA signal with a multimeter? ›

Termination check
  1. Switch-off the power to the NMEA 2000 network.
  2. Connect the test cable to the diagnostic T-connector next to the power insertion point.
  3. Using the multimeter, measure the voltage between the RED and BLACK wires. ...
  4. Measure the resistance between the WHITE and BLUE wires.

What is the difference between a NMEA 2000 drop cable and a backbone cable? ›

The drop cables are smaller in diameter and more flexible than backbone cables for easy connection to NMEA 2000 devices. For connection to an NMEA 2000 tee connector. The yellow couplers connect to the corresponding Ancor tees creating a simplified, color coded network installation.

What is the difference between marine wire and household wire? ›

Beyond being tinned, marine cable is larger than say automotive cable at the same size. So, 6 AWG marine cable contains more copper than 6 AWG automotive cable. The more copper, the better the current carrying capacity of the cable. Marine cable also carries a pliable and durable PVC jacket.

What are the 2 types of cables connect network equipment? ›

Shielded and unshielded twisted pair cables are often recognized as the common twisted pair network cable types in networking solution, which can be described as STP and UTP twisted pair cable respectively.

What is the difference between NMEA and NMEA 2000? ›

NMEA 0183 operates on a 1-to-1 connection method using RS232/RS422, where multiplexers and buffers are required to connect multiple devices 'together'. NMEA 2000 uses CAN with a backbone / drop cable network system, where all devices on the network talk to one another.

Are all NMEA 2000 devices compatible? ›

NMEA 2000 is based on the SAE J1939 high-level protocol, but instead defines its own messages. NMEA 2000 devices and J1939 devices can be made to co-exist on the same physical network.

Does NMEA 2000 provide power to devices? ›

A large amount of NMEA 2000 devices are powered solely from the backbone, and this power is used to operate the device. Whilst this is the case for most devices, not all devices are powered from the NMEA 2000 network completely.

How many wires does a NMEA 2000 cable have? ›

An NMEA 2000 cable contains five wires: two for 12 VDC power and ground, two for the data pair, and one shield wire.

How many wires are there in a NMEA network cable? ›

1.1 Network Topology

The NMEA 2000® cable system includes five wires within a single waterproof cable: two signal wires, power and ground wires, and a drain wire.

Does NMEA 2000 have Ethernet? ›

The Gateway is equipped with a standard Ethernet RJ45 connector, and you may need a proprietary adapter to connect it with your vessel's network; direct connection to PC with standard computer cable is also supported.

What voltage does NMEA use? ›

4 - NMEA Listener Specification

A listener must operate with a minimum differential input voltage of 2.0 Volts, and not take more than 2.0mA from the line at that voltage. The NMEA standard document shows a circuit that will meet this requirement.

What does NMEA stand for? ›

NMEA is an acronym for the National Marine Electronics Association. NMEA existed well before GPS was invented. According to the NMEA website, the association was formed in 1957 by a group of electronic dealers to create better communications with manufacturers.

How long CAN a NMEA 2000 drop be? ›

According to the NMEA 2000 standards, the maximum length of a drop cable is 6 m. However, it is always best to use the shortest drop-cable length as possible.

Between which two pins wires should you measure the NMEA 2000 network resistance? ›

Measure the resistance between pins 1 (Bare) and 3 (Black) of a network connector. This measurement should be a very high resistance (OPEN).

What might occur in NMEA 2000 network topology If one device in line should fail? ›

What might occur in NMEA 2000 network topology if one device in line should fail? There will be no interruption to all other devices. Yes, the system will take the device off the network. But, what if the backbone cable fails, then no network.

What engines are compatible with NMEA 2000? ›

They are Yamaha, Suzuki, Honda and Evinrude. Honda - All 225 Hondas from 2010 and nwer, as well as the 60 and 250HP Hondas are NMEA2000 Capable. They require a Honda NMEA Interface Cable. This cable will attach to a plug inside the engine cowling on one end, and then connect to a NMEA2000 T Connector on the other end.

What is needed for NMEA 2000? ›

The main components of a NMEA 2000 network are T-connectors, terminators, backbone/drop cables, and a power cable. *The field-installable connectors are used to create custom-length drop cables and custom-length backbone extension cables.

How do I get NMEA from GPS? ›

To read NMEA GPS data,
  1. Find an application such as AT Command Tester that can parse data from the NMEA port.
  2. Connect the GPS device over the interface that is supported by the device.
  3. Display NMEA GPS data read from the NMEA port.

How long can a NMEA 2000 drop cable be? ›

The maximum length of an NMEA 2000 cable used to connect any device or accessory to a T-Connector is 20 feet (6 meters).

How long can a NMEA 2000 drop be? ›

According to the NMEA 2000 standards, the maximum length of a drop cable is 6 m. However, it is always best to use the shortest drop-cable length as possible.


1. Installing an NMEA 2000 Backbone on a Boat
(Pacific Yacht Systems)
2. Tech Tuesday NMEA 2000
3. Support: Creating a NMEA 2000® Network
4. NMEA 2000 power consumption and devices
(Dragon Marine Systems)
5. NMEA 2000 Top Tip: Using a 4-Way-T vs multiple T-pieces ▶ Actisense A2K-4WT
6. Actisense NMEA 2000 network 4-way drop cable (A2K-4WD)
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