Basic nmea 2000 question .......

[CPD]

I have bits of an 0813 (system is too posh a word !) and looking at replacing instruments and display(s) so will have to look at nmea 2000 (and am very open to doing so).

If in an nmea 2000 network you have two separate transducers measuring the same thing (I'm thinking specifically speed through the water - lets say transducer A and transducer B), then on your display instruments (perhaps a shiny MFD), how would you know which was which ?. (My question is based on my very basic understanding that various parameters have "codes" telling the network what the following data is, followed by the data itself, which makes up the nmea 2000 'sentence' ?. If the 2 'codes' are for the same parameter ie speed through the water, then ???

I hope the question makes sense ??. Many thanks.

 

[kwb78]

NMEA2000 is a bit more complex than 0183. Devices have their own ID on the network so it is possible to have more than one sending the same type of data without them interfering with each other. Most MFDs can recognise data from multiple transducers of the same type and will either automatically select the one it thinks is best, or allow you to determine their priority.

 

[[70521]]

MDF? What does that TLA mean?

 

[vas]

As kwb78 states, on an mfd, you CAN select source. On my Garmin setup though I wond be able to show BOTH instruments data though. Not sure how other brands h/w deal with this.
Things get slightly more complicated if on the same bus you have the typical square 4-5in multidisplays. Not sure you can select sources on them, pretty sure I cannot on my Garmin gmis.
Only yesterday swapped reported seawater temp from dst800 that was reporting 60c to the fish finder (admittedly on Garmin network connection and not straight n2k).

 

[vas]

MDF? What does that TLA mean?

What does TLA mean?
Multifunctional display is mfd (if that's what you're asking)

 

[Hoolie]

What does TLA mean?

Three Letter Abbreviation

 

[Hoolie]

My Raymarine i70's can select some data sources where the same data is available. My system is a bit mixed generations of kit and I haven't yet bottomed out exactly what the limitations are.

 

[Norman_E]

Just remember that your existing transducers will be either sending NMEA0183 data or may even be using propriety data for a specific instrument. If they send NMEA0183 sentences, and you want to keep using them then a simple and not too expensive solution is to use NMEA0183 to 2000 converters. I had an Actisense NGW1 converting wind data from an olsd system to NMEA2000 and it was very successful. NGW-1 NMEA 2000® Gateway
Another useful resource is here Maretron | N2KBuilder I designed my system on it. If you put in all your cable lengths it even shows you the voltages at each point in the system.

 

[adwuk]

I had an Actisense NGW1 converting wind data from an old system to NMEA2000 and it was very successful.

The only problem that may present is if two sources on the 0183 side are transmitting the same data. Anything that it converted from 0183 to 2000 by the gateway will have the gateway as the source, not the original transducer, and so you won't be able to select one over the other. That said, we have an Actisense gateway, and it has allowed us to keep an old plotter going alongside the new instrument network.

 

[prv]

The only problem that may present is if two sources on the 0183 side are transmitting the same data. Anything that it converted from 0183 to 2000 by the gateway will have the gateway as the source, not the original transducer, and so you won't be able to select one over the other.

The NGW1 only has a single NMEA0183 port, so you wouldn’t have multiple devices connected to it anyway. If you had multiple NGW1s (to bring in multiple 0183 devices) then each would have its own id - though as always it’s up to the display how well it allows you to work with the multiple sources.

Pete

 

[jwfrary]

Some of the early n2k devices can't select a source I'm thinking the st70 raymarine so watch out for that.

Its probably best to avoid having two data streams of the same thing on the network, especially things like AIS which uses or can use a lot of the bandwidth on the network

 

[cpedw]

I have bits of an 0813 ...

MDF? What does that TLA mean?

Dyslexics of the world, Untie!

 

[adwuk]

...

 

[CPD]

TLA .............................. Thanks, Lovely Answers !

Thanks chaps

 

[MikeCC]

Tinley Electronics do an NMEA2000 transducer changeover switch, so display will only 'see' one at a time.

Some displays may allow you to prioritise sources in case of failure.

 

[prv]

Tinley Electronics do an NMEA2000 transducer changeover switch, so display will only 'see' one at a time.

It changes over based on which tack you‘re on, in case your hull’s hydrodynamics interfere with speed or depth sensors in an asymmetrical way. That’s probably not what the OP wants.

Pete