NMEA2000 connection. Please edjumacate me...

HawkX66 · Feb 16, 2021

I have an ICOM M330 VHF with NMEA2000 and a gps puck connection. I also have an Raymarine Element 9hv with NMEA2000 connection available.
If I wanted to connect the two of them, would I just need to buy one NMEA2000 cable and connect them or do you need the "back bone" that I've seen mentioned.

KevinC · Feb 16, 2021

HawkX66 said:
I have an ICOM M330 VHF with NMEA2000 and a gps puck connection. I also have an Raymarine Element 9hv with NMEA2000 connection available.
If I wanted to connect the two of them, would I just need to buy one NMEA2000 cable and connect them or do you need the "back bone" that I've seen mentioned.

The NEMA2000 (N2K) network is going to require power and terminators at the ends. I do not believe you can simply plug one into the other without power being provided. The starter kits generally will give you what you need to get started: power, terminators and a couple of T connections.

-Kevin

HawkX66 · Feb 16, 2021

KevinC said:
The NEMA2000 (N2K) network is going to require power and terminators at the ends. I do not believe you can simply plug one into the other without power being provided. The starter kits generally will give you what you need to get started: power, terminators and a couple of T connections.

-Kevin

Thanks Kevin. I've been trying to read up on it, but a couple things weren't clear. For instance, does the power from the back bone power the equipment also or do you still have to run separate power?

KevinC · Feb 16, 2021

HawkX66 said:
Thanks Kevin. I've been trying to read up on it, but a couple things weren't clear. For instance, does the power from the back bone power the equipment also or do you still have to run separate power?

Your main equipment (MFDs, VHFs, etc) still need to be powered direct - this is just for the network power. I believe it is used by the sensor devices that need power that you would attach (ie: GPS puck, etc) without having to power them.

-Kevin

HawkX66 · Feb 16, 2021

KevinC said:
Your main equipment (MFDs, VHFs, etc) still need to be powered direct - this is just for the network power. I believe it is used by the sensor devices that need power that you would attach (ie: GPS puck, etc) without having to power them.

-Kevin

Bummer. That would have been handy as heck! I guess you wouldn't want to pop one breaker and lose all electronics though, so that makes sense. Thanks for the help!

hughespat57 · Feb 16, 2021

assuming the two devices are physically close is why you want to keep it simple?
The simplest you can do is two very short "drop" cables, and a muli-Tee connector, with terminators on each end of the tee.

You are not required to provide a power feed to the backbone if all the NMEA devices have local power.

This way you can later extend the backbone by simply removing one terminator, add backbone cable and a tee, re-install the terminator on that tee. Locally you can add more devices to the multi-tee dependent on how big a one you buy

https://www.nmea.org/Assets/20090423 rtcm white paper nmea 2000.pdf

HawkX66 · Feb 16, 2021

Thanks Patrick. Now that I understand the power requirements I should be good to go. This is a pretty simple network by the looks of it.
I love my toys, electronics included, so I'll probably add on at some point. For now all I have is the Element 9hv and the VHF that will be connected. I'll have to see if there's a way to connect my Autometer GPS speedometer also.

Skybolt · Feb 16, 2021

HawkX66 said:
... Now that I understand the power requirements I should be good to go. This is a pretty simple network by the looks of it. ...

Most NMEA 2000 devices are not self powered and if they are, it is most likely turned off by default. But you need to be carful and know if they are self powered or not and how to turn it on/off. You can not have more then one device powering the bus. In most cases it's better to have a switched power source for the NMEA 2000 bus and leave the individual devices internal bus power set to off. Less confusion when you start expanding the network.

HawkX66 · Feb 16, 2021

SKybolt said:
Most NMEA 2000 devices are not self powered and if they are, it is most likely turned off by default. But you need to be carful and know if they are self powered or not and how to turn it on/off. You can not have more then one device powering the bus. In most cases it's better to have a switched power source for the NMEA 2000 bus and leave the individual devices internal bus power set to off. Less confusion when you start expanding the network.

I plan on having switched power to the backbone. The only thing I'm trying to figure out now is if there is an adapter to go from NMEA 2000 to my GPS speedometer. It looks like there is a way, I just need to find out how the adapter connects before I buy it.

Skybolt · Feb 16, 2021

Not sure what type of gauge that is (make and model). The "External NMEA Data" is most likely NMEA 0183 which is a device to device non networked connection like RS-232. NMEA 2000 is a networked connection, CAN-Bus or Device Net as it is called. Which is a totally different thing and goes way past the connector type and has strict protocols associated with it. Completely different animals that require a converter to be used together on the same bus.

HawkX66 · Feb 16, 2021

SKybolt said:
Not sure what type of gauge that is (make and model). The "External NMEA Data" is most likely NMEA 0183 which is a device to device non networked connection like RS-232. NMEA 2000 is a networked connection, CAN-Bus or Device Net as it is called. Which is a totally different thing and goes way past the connector type and has strict protocols associated with it. Completely different animals that require a converter to be used together on the same bus.

It's an Autometer Pro Comp Marine speedo. I'd just like to figure out a way where I don't have to mount the gps puck that came with it if possible.

Product
200635-33

https://www.autometer.com/3-3-8-gps-speedometer-0-50-mph-marine-silver.html

Skybolt · Feb 16, 2021

HawkX66 said:
... I'd just like to figure out a way where I don't have to mount the gps puck that came with it if possible. ...

Bad news, it looks like that doesn't support any NMEA data at all and requires a GPS connection to be used correctly. Auto-Meter isn't a marine application device. It's meant for cars and trucks. They are looking for an analog GPS signal.

"Requires AutoMeter 5283 GPS antenna or can work with most aftermarket GPS antenna/receivers with use of AutoMeter 5214 mating wire harness"

HawkX66 · Feb 16, 2021

SKybolt said:
Bad news, it looks like that doesn't support any NMEA data at all and requires a GPS connection to be used correctly. Auto-Meter isn't a marine application device. It's meant for cars and trucks. They are looking for an analog GPS signal.

"Requires AutoMeter 5283 GPS antenna or can work with most aftermarket GPS antenna/receivers with use of AutoMeter 5214 mating wire harness"

It's Autometer's Marine application speedo, but it looks like I'll have to use the puck that came with it. I'll mount it under the dash away from any metal or power and see how it works. Fiberglass is suppose to be invisible to GPS and there's only window above it so we'll see. Not a big deal. It would have been nice though.

Skybolt · Feb 16, 2021

HawkX66 said:
It's Autometer's Marine application speedo, but it looks like I'll have to use the puck that came with it. I'll mount it under the dash away from any metal or power and see how it works. Fiberglass is suppose to be invisible to GPS and there's only window above it so we'll see. Not a big deal. It would have been nice though.

Sorry, should have said their not noted for their marine applications. But you my not be happy with the update times if the receiver isn't able to get a strong signal. Even though there supposed to be invisible, I've noticed it doesn't really work that way. Good luck!

HawkX66 · Feb 16, 2021

SKybolt said:
Sorry, should have said their not noted for their marine applications. But you my not be happy with the update times if the receiver isn't able to get a strong signal. Even though there supposed to be invisible, I've noticed it doesn't really work that way. Good luck!

I might have to put it on the windshield then. Oh well... Thanks for the comments!

Todd320 · Feb 16, 2021

That gauge appears to be recalculating speed based upon gps coordinates. Your Raymarine device is already doing that calculation. You might be able to find a NMEA 2K gauge that is simpler in that it just reads the calculated speed information from NMEA 2k, and displays it.

HawkX66 · Feb 16, 2021

Todd320 said:
That gauge appears to be recalculating speed based upon gps coordinates. Your Raymarine device is already doing that calculation. You might be able to find a NMEA 2K gauge that is simpler in that it just reads the calculated speed information from NMEA 2k, and displays it.

I'm sure there's another gauge out there that would do that, but I already invested in these matching gauges and it's not really a big deal to me. It would have been a nice to have though.

b_arrington · Feb 16, 2021

hughespat57 said:
assuming the two devices are physically close is why you want to keep it simple?
The simplest you can do is two very short "drop" cables, and a muli-Tee connector, with terminators on each end of the tee.

You are not required to provide a power feed to the backbone if all the NMEA devices have local power.

This way you can later extend the backbone by simply removing one terminator, add backbone cable and a tee, re-install the terminator on that tee. Locally you can add more devices to the multi-tee dependent on how big a one you buy

https://www.nmea.org/Assets/20090423 rtcm white paper nmea 2000.pdf

This may be correct that if the N2K devices are all separately powered that the network doesn't need it's own power source (I didn't read the technical doc linked). However, everything I've read indicates that best practice is to have the network have it's own power source. This is via a 12v connection to one of the terminals. I think it I were installing the network I would power it, even for a simple application.

Skybolt · Feb 16, 2021

b_arrington said:
This may be correct that if the N2K devices are all separately powered that the network doesn't need it's own power source (I didn't read the technical doc linked). However, everything I've read indicates that best practice is to have the network have it's own power source. This is via a 12v connection to one of the terminals. I think it I were installing the network I would power it, even for a simple application.

Yep I agree, my previous post states that as well. But multiple devices can not power the same NMEA 2000 segment even if they are powered. Most devices that have there own power supply, do not power the NMEA 2000 section of their electronics and require that to be powered from the N2K network itself. Hence the LEN always listed on the device itself.

dtfeld · Feb 16, 2021

You'll need a NEMA2000 starter kit. Gets you power on the backbone , the terminating resistor's and 2 drop cables. This will connect 2 devices. and you can add from there. If its just 2 items at the helm, this might work, the variable being the length of cables you need.

NMEA2000 connection. Please edjumacate me...

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