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Multiple NMEA 0183 Devices and

Old 02-22-2013, 02:22 PM
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Default Multiple NMEA 0183 Devices and

Best way to hook them up.

I have 2, Raymarine E90W's and 2 ICOM M504 VHF radios.

Would like to have redundancy at the MFD and radio end.

I can think of a few ways to hook all this together but would like input from others on best way.

I can hook each radio to one MFD each but would be worried that NMEA data may "collide" on the Raymarine network between the two MFDs (E90s) or I can put toggle switches to choose which radio and MFD are "active".

Any other ideas? How would you do it?
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Old 02-22-2013, 03:22 PM
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I would connect each of the radios to one MFD. The MFD's will do the necessary filtering if needed to avoid duplicate messages on SeaTalk ng and HS.
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Old 02-22-2013, 04:30 PM
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I'd just take one gps and put the nmea wires u need on a buss and connect ur radios to that buss.
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Old 02-22-2013, 07:53 PM
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Originally Posted by bradv View Post
I'd just take one gps and put the nmea wires u need on a buss and connect ur radios to that buss.

I thought of that too. I think that the problem would lie in the fact that both radios are NMEA talkers too - they output location data for DSC contacts - so you'd have the radios spitting out duplicate data onto the bus. As I said, I think that's what would happen.

The other problem would be that I'd lose redundancy of the position data from the MFDs to the emergency DSC distress call on the radios if for some reason that one MFD was down or off.

Thanks. It's a good suggestion but I'm thinking there's a better way.

Unless someone chimes in with a better way to do this, I'm inclined to do what Abbor said. One radio to each MFD and hope that comms between the two MFDs doesn't get screwed up with duplicate data.

I did my boat a little differently. I have a C70 and a C80 and 2 radios but only one of the radios is DSC capable. I sent the MFD NMEA outputs thru a DPDT toggle and I can choose via that toggle which of the MFDs is actually "talking" on the bus. Default for mine is that the C80 is the talker but both MFDs recieve the data from the radio full time. Heck, maybe that's my answer to the duplicate data between the two MFDs and whether it'll screw something up. It's not exactly the same, but close. That setup has worked great on mine for ~4 years now.
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Old 02-22-2013, 09:08 PM
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NMEA 183 talkers can not be connected togeteher, NMEA 183 is a point-to-point connection, not a bus or network.

The alternative if you wan't full reduendancy is to add one NMEA 183 to NMEA 2000 converter for each VHF and then connect everything together using SeaTalk ng or NMEA 2000. A couple of SeaTalk ng to NMEA 2000 micro-C adapters would also be needed in addition to a NMEA 2000 or SeaTalk ng starter kit. I would recommend using a standard micro-C backbone and adapters to connect to your MFD's since I dislike non-standard NMEA 2000 cabling.

The converter to use is Actisense NGW-1.

http://www.actisense.com/products/nmea-2000/ngw1.html
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Old 02-22-2013, 09:15 PM
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Ok, let me get this straight in my brain. You're saying that I can't connect 1 radio tx to one MFD rx and the MFD tx to the radio rx and then do the same with the other radio and MFD? That wouldn't be a network, that would be 2, 2 way point to points -- wouldn't it?

I like your convert to NMEA 2000 idea the most. I have to buy some of this stuff anyway to hook the Yamaha Command Link network up to the E90s.
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Old 02-22-2013, 09:31 PM
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If using NMEA 183 you have to create two point-to-point connections. Tx and Rx between VHF1 and MFD1 and Tx and Rx between VHF2 and MFD2. If going the NMEA 2000 route everything will be networked to give the best redundancy. A networked system will still be operational with one dead VHF and one dead MFD independent of which of the unit have failed.

I also prefer NMEA 2000 cabling, due to this my next VHF will be a Simrad RS35, RS35 has in addition to NMEA 2000 also built-in AIS receiver.
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Old 02-23-2013, 03:26 AM
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Still do a buss and each gps goes to a radio. Not sure why the dsc vhf would be talking on the 0183 network. And if it did those would be a different set of wires since its either an input or output wire.
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Old 02-23-2013, 05:45 AM
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Yes, the radios actually have input and output. If you are talking to another boat using DSC, position data for that boat is apparently encoded into a header in their transmissions. The radio pulls out that data and puts it on the 0183 output and the MFD will plot it.
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Old 02-23-2013, 07:45 AM
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Originally Posted by bradv View Post
Still do a buss and each gps goes to a radio.
No. As "abbor" pointed out, NMEA 0183 is ALWAYS a point-to-point connection; it does not support a "buss" topology.


Not sure why the dsc vhf would be talking on the 0183 network.
Because so many VHFs (particularly including the OP's) fail to support NMEA 2000. So 0183 is all we have.


And if it did those would be a different set of wires since its either an input or output wire.
Well, a different pair, but the same "set". A full NMEA 0183 port has four terminals: TX+, TX-, RX+ and RX-. And again, without a multiplexer, only one "Talker" can connect to any given "Listener".



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Old 02-23-2013, 08:00 AM
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Originally Posted by abbor View Post
If using NMEA 183 you have to create two point-to-point connections. Tx and Rx between VHF1 and MFD1 and Tx and Rx between VHF2 and MFD2. If going the NMEA 2000 route everything will be networked to give the best redundancy. A networked system will still be operational with one dead VHF and one dead MFD independent of which of the unit have failed.

I also prefer NMEA 2000 cabling, due to this my next VHF will be a Simrad RS35, RS35 has in addition to NMEA 2000 also built-in AIS receiver.
Doing that tight now with two Standard GX2150's and a Garmin 7215 and 7012. Each VHF to one MFD to share DSC and AIS data at 38,400 baud not the much slower 4800. MFD's will share DSC/AIS data over their "ethernet" Garmin network. N2K would be easier to connect and it's baud rate is faster than 0183 but with numerous N2K devices on the network transmitting in sequence, the dedicated 0183 connection could feasibly be a faster method of exchange.
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Old 02-23-2013, 02:29 PM
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I will be doing it on the NMEA2000 buss. Abbor's idea on that is far superior in terms of redundancy and practicality than any other way I can think of. As one of these radios is in the flybridge and one is in the console, doing it any other way would leave the possibility that you could push the "red button" and a distress call could go out w/o coordinates. This way, as long as at least one of the displays is operational, you can push the red button on either radio and expect the system to be fully operational.
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Old 02-23-2013, 07:08 PM
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Originally Posted by Back-in-Black View Post
I will be doing it on the NMEA2000 buss. Abbor's idea on that is far superior in terms of redundancy and practicality than any other way I can think of. As one of these radios is in the flybridge and one is in the console, doing it any other way would leave the possibility that you could push the "red button" and a distress call could go out w/o coordinates. This way, as long as at least one of the displays is operational, you can push the red button on either radio and expect the system to be fully operational.
As Abbor said - Simrad RS35 has NMEA2000. So does the new Lowrance Link-8 - the only difference is the RS35 supports 2 wireless handsets - where the Link-8 does not. But both support dual channel AIS reception.

I just bought a Lowrance Link-8 for my dads boat. I'll have it in about 10 days - and I'll let you know what I think about it. The Link-8 has a street price of around $305 - which is less than most charge for a pure NMEA2000 AIS receiver.
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