nmea 2000 Q

simonfraser

simonfraser

Well-Known Member
Joined
13 Mar 2004
Messages
7,609
Location
Outboards 4 mobo’s, unless you do a lot of miles
Visit site
I have added a drop nmea cable to an existing nmea backbone
connecting this to a wifi transmitter
have cut the nmea plug off
black and red wire 12V
light blue constant 2.5 volt
white 150 to 200 mV varies
the white wire should cycle on off by about 4V ?

have checked the resistance between white and light blue cable with power off, 60 ohms

i have three devices on the nmea network, depth sounder, garmin gps and fusion, all working and interfacing

have i added a dud cable ? Or ?
 
Last edited:
I’ve done the same to mix both Ng and Device net, both with back bone and drop cables, as long as connections are soldered, heat shrinked never had a problem, have noted that Ng drops have the extra wire for sea talk
 
I’ve never looked at the voltages, measuring comms with a normal meter can often show strange readings, you really need an oscilloscope to see what’s going on as you could be reading average voltage from data comms,
 
Daverw said:
I’ve never looked at the voltages, measuring comms with a normal meter can often show strange readings, you really need an oscilloscope to see what’s going on as you could be reading average voltage from data comms,
Click to expand...

tnx, that’s why I’m getting v odd readings on the white wire
wifi transmitter is chucking out gibberish from what I can see, will do a screenshot later
 
White/blue wires are usually data in nmea2000. You won't get much useful putting a voltmeter across them. As previous poster says, an oscilloscope would show more, or better still a known good nmea2000 display.

You've not said what the WiFi transmitter is. We're assuming it's got an nmea2000 connection.

If so, what are you seeing the gibberish on?

You've also not said how you've configured it to send on the WiFi.... udp, tcp or just raw nmea2000 so hard to guess what you will need to read the data.
 
YakBak, one in previous boat faultless
there is an inbuild logger which shows gibberish on all the Rx speeds
Steve from YakBak suggested a lower Rx speed, see above

have rebooted it several times no better when not connected to hotspot

updated overnight - it gets stuck updating when connected to the hotspot this am

not working correctly as far as I can see, have mailed Steve again just now
 
Forgive me if I'm missing something but I can only see the YakBak advertised as NMEA0183 on the Yakbitz website, yet you say you are wiring it direct to NMEA2000 which runs a very different interface and protocol.

The yakbitz website graphics also show the yakbak speed as up to 38400 baud, also implying it is NMEA0183 only.

Perhaps check with them first to see if they really have supplied you with an NMEA2000 version.
 
As a summary, NMEA 0183 has a couple of wires, has only one talker on the wire (but up to about four listeners) and runs at 4800 baud ( or 38400 baud if you have AIS in the connection)... It also talks in what are called sentences which are easy to decipher with a simple serial port on a PC with some terminal emulation software that will just read the bits from the wire.

NMEA2000 on the other hand (also known as Simnet or Seatalk NG in the sailing world, depending on manufacturer) is electronically a 'bus' with a terminator at each end and any device can talk and listen. Connections are via the T pieces mentioned earlier and the bit rate is 230400 bits/sec. You'd need a faster oscilloscope to pick up signals on the wire and you'd also not manage to decode the signal without extra decoding software.
NMEA 2000 also has the extra red/black wires in the bus because it allows you to power devices from the bus as well. NMEA0183 was just the data wires so didn't provide power itself to any connected devices.

Hope this helps. If Yakbitz does do the NMEA 2000 version then perhaps it needs to be added to the website.

Oh and if you do have an NMEA0183 WiFi converter and want to keep it, in order to connect to the NMEA2000 backbone, you will likely need a convertor like the ones made by for example Actisense.
 
By the way... your resistance measurement check across the white and blue being 60 ohms does suggest you have NMEA2000 on board. It's precisely what the two 120 ohm terminators will present as a resistance, since they are effectively connected in parallel across the ends of the bus. Sounds like your bus is correctly terminated.
 
Martin_J said:
Forgive me if I'm missing something but I can only see the YakBak advertised as NMEA0183 on the Yakbitz website, yet you say you are wiring it direct to NMEA2000 which runs a very different interface and protocol.

The yakbitz website graphics also show the yakbak speed as up to 38400 baud, also implying it is NMEA0183 only.

Perhaps check with them first to see if they really have supplied you with an NMEA2000 version.
Click to expand...

doh, yea just noticed that too ?

Steve just helping me out with a circuit ……
 
Are you trying to connect via the nmea2k not the nmea0183 connection? From the cable you describe it seems you are, that will not work completely different comms systems. The nmea0183 does not provide power just comms so you will need to power separately. Our Lawrence plotter has both and will do them together although we don’t use 0183 anymore
 
+1 to what previous posters say.

sort out what you want from what you can get.
A wifi N0183 WILL NOT connect on a N2K network no matter what, fullstop (9600baud and 32something vs 250k is simply not possible)!
Your Garmin plotter (second EDIT! manual does mention N0183 OUT port, god knows what it supports other than an old A/P!) .

Thing is connecting to your Garmin plotter N0183 and configuring it as OUT, it will only send to the wifi thing what it will export. Now, what it does export and IF it picks up data from the N2K bus (which also goes to the plotter) and convert it to N0183 is another story and slightly sci fi -f.e. engine data N2K PGNs dont have equiv in N0183 for starters. Depth, wind, etc may just work (depends on how the data come into the plotter)

so basically, imho the N0183 wifi is not going to be of much use if all the data in your boat is N2K.

V.
 
Last edited:
vas said:
+1 to what previous posters say.

sort out what you want from what you can get.
A wifi N0183 WILL NOT connect on a N2K network no matter what, fullstop (9600baud and 32something vs 250k is simply not possible)!
Your Garmin plotter (second EDIT! manual does mention N0183 OUT port, god knows what it supports other than an old A/P!) .

Thing is connecting to your Garmin plotter N0183 and configuring it as OUT, it will only send to the wifi thing what it will export. Now, what it does export and IF it picks up data from the N2K bus (which also goes to the plotter) and convert it to N0183 is another story and slightly sci fi -f.e. engine data N2K PGNs dont have equiv in N0183 for starters. Depth, wind, etc may just work (depends on how the data come into the plotter)

so basically, imho the N0183 wifi is not going to be of much use if all the data in your boat is N2K.

V.
Click to expand...


tnx V, indeed, totally agree with you !!
bought the wrong interface as that worked with the prev boat :rolleyes:
this bit has now gone from intersting to annoying
next thread
 
Seriously though. You should be able to connect the NMEA 0183 input of the WiFi bridge to the NMEA 0183 output of the Garmin. The Garmin should then be able to sent it all the NMEA0183 output that the Garmin can output.

You said you didn't see anything on the Garmin NMEA0183 debug. Maybe because that might only show input traffic on the Garmin NMEA0183 port (I'm guessing).

As Vas says, you'll never see engine type data that you might one day have on the NMEA2000 bus, but you should at least be able to get wind, GPS and depth information as NMEA0183 sentences.

Fusion is also something that will only be on the NMEA2000 so I wouldn't expect to see that on NMEA0183 in any form.
 
Hold on... just reading the manual for the Garmin Echomap UHD 72cv that you included a link to, it says it can host a WiFi network itself. Do you even need the separate WiFi bridge?

Screenshot_20220626-122232_Samsung Internet.jpg
 
Martin, if it's the same as the one on GPSMAP 740 I had a few years back, the wifi is useful to replicate the plotter screen on your mobile/tablet. Not sure what app (bar garmin's own!) will connect to this wifi
Simon has to investigate that
 
You must log in or register to reply here.

Share this page

Top