Multiple MFD12 sharing one NMEA2k bus?

wkearney99

Furuno Super Fan
Is it possible to connect one NMEA2k bus across 4 MFD12 displays?

Right now I have a network of devices that requires 3 of the 4 MFD12 to be always on. NMEA0183 into one MFD12, one NMEA2k into a second and then a whole other NMEA2k into a 3rd, along with sirius weather, radar and AIS on Ethernet (all 3 are furuno units).

Lower station:
Hub101 - all 4 displays, weather, radar and AIS (one port left free)

MFD1
- 0183
-- B&G gauges (and what used to be a depth/temp sensor)
- 2k
-- Airmair DST2000 (depth/speed/temp)
-- PG-700 heading

MFD2 - Ethernet only

Upper station:
MDF3
- 2K
-- two B&G Triton2 gauges

MDF4
- 0183
--GP-320b GPS antenna

I plan on eliminating the use of 0183 for GPS by replacing it with an NMEA2k unit.

I'm assuming a cable change would be necessary in order to avoid having more than one MFD12 trying to power the bus at the same time.

Is it possible? If so, what cabling pieces would be necessary to make it happen?
 
I should add there's also a Simrad AP26 autpilot connected, but it was not powered up when I was debugging the rest of the connections. I'm assuming it's likely plugged in with the other 0183 devices.
 
By design the MFD12 (NN3D) can NOT have NMEA 2000 to more than one MFD. The only way you can have NMEA 2000 connected to more than one display is if they are completely different buses. This is because the NN3D network bridges the NMEA 2000 data via the normal network connection. If you have two (or more) connected to the same NMEA 2000 bus, you create data loop problems. Unlike the newer TZT or TZT2, you don't connect each display to the NMEA 2000 bus.
 
Ok, thanks for the reply.

Is there no way around this? Short of replacing the MFDs, of course. That's not on the budget horizon at the moment.

Is there no way to tell the MFDs to use one specific source network for the data and not others?

I get the data loop scenario, as I'm familiar with networks in general. As in, dual-homing hosts doesn't come without configuration complications, to say nothing of just straight-up looped connections.

But to put all that effort into including NMEA2k and not support the likely scenario of multiple displays?

If it's genuinely impossible then is there any downside to funneling all of the NMEA2k devices through just one MFD? Is there going to be a performance bottleneck that would affect performance? Both on that MFD and on the others trying to get the data over Ethernet.

I'd like to have the option to not have all four MFDs running at the same time. That and I'd like to have some redundancy in the event one of them goes on the fritz. Worst-case I'd have enough leeway in the NMEA2k networking cabling (or suitable extensions on-hand) to allow manually dis/re-connecting the bus in the event of an MFD failure. Or am I then getting into a more complex scenario of having to totally re-initialize the configuration?

I'm coming from a boat that had considerably less battery capacity than this one. I like to avoid wasting DC power by having devices running when they're not needed.
 
Sorry, it was how the NN3D design was done. The entire system is designed to turn on together (using the power sync feature) and go off together. Any machine not needed will boot up and go into sleep mode. One MFD per NMEA 2000 bus, ONLY. It has advantages if you want to have several NMEA 2000 buses and let the system see everything. It is how it is programmed and designed. If you want to have the system work properly, you will follow the design rules. The NMEA data input on one machine (even 0183) is shared to all machines. Everything has pluses and minuses.
 
Ok, are there any performance downsides to funneling them all through just one MFD12? Will that slow down the MFD itself or the data streams to the other units?

Are any of the display pages more computationally intensive than the others? On the lower helm I could have the master running something less intensive if that would help.

I'm fine with whatever design requirements go into the system. Knowing them is key. I've not run across much that mentions the pros/cons/gotchas on setup options. There's alwys going to be some. I'm new to these units, so bear with me if I'm asking dumb questions. My goal is make sure what I've got it as properly set up as it should be.

I've got the "ime44440d_1_mfd8_12__rel_feb_2014.pdf" file. On pg 12 it mentions putting "as many instruments as possible" connected directly to the Master. Which is not how mine are currently set up. Fortunately there's very good access to allow rearranging the NMEA2k cables accordingly.

Are there any other PDFs online of the setup/initialization process? Or any do/don't/best practices tech notes?
 
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