Autopilots, Chartplotters and other Nmea devices..

[David Underwood]

I am about to tackle the task of connecting everything together. Kinda confusing and I thought maybe there might be some helpful hints, ideas or suggestions out there before I proceed. I have seen a couple of postings in the recent past, but want and need more! Any and all comments welcomed. Would love to hear what type of wire was used and how it wass run and how the actual connections were made. Placement of instruments and GPS/Chartplotter would be interesting also. So, please post. Thanks, David Underwood

 

[Derek Rowell]

Connecting NMEA instruments

David,Connecting NMEA instruments together is not a simple task because on any NMEA network there can be only one "talker". (A device that generates and transmits data is a "talker", a device that receives and displays data is a "listener".) Thus the data on the data-out line from the designated talker is connected to the data-in line on any listeners. If you want to integrate data from several instruments, say a GPS and a wind indicator, you have to use a NMEA multiplexer, which will run you $150 or so. A few instruments, such as the Raymarine ST60 Multi, will do some data integration. The wiring is not really critical since the data rate is low (4800 baud). Almost all NMEA devices will communicate with a PC through the serial input port. Note that the proprietary networks, such as Raymarines SeaTalk, usually allow multiple talkers.Derek

 

[Don]

not as difficult

It is not as difficult as one would think. I have seen them as simple as using a terminal board. There is only the internal wire along with a shield. Keep the shield wrapped around the feed wire and sending wires as close to the terminal board as possible, and keep these away from other voltage wires. I have fed as many as three devices from one source without having to worry about inadequate signal.

 

[David Underwood]

Follow up Question....

So, I have the WP30 autopilot, I have the Navman 3100 instruments (Multi3100=depth, knot, temp. and also the wind3100 and repeater3100) and I have the Std. Horz. CP150C. The WP30 has only one Nmea grd, and one Nmea Input. The Navman instruments can talk to each other with their own language on separate wires, but they also have two Nmea outputs : one I can use for the autopilot, one for the Gps/chartplotter. Do I / can I connect both the Wind instrument (Nmea out) and the GPS (Nmea out) to the same wire (Nmea In of the autopilot) at the same time .. say twist all 3 wires together? I sure hope I don't have to spend another 150 bucks... please don't tell me that.Now, maybe the Nmea out of the GPS/Chartplotter will carry all the other input information from the wind instrument to the autopilot without the extra connection.!? (not sure if I'm asking a question or posing an unsure statement) Please bear with me, I may be slow, but I can learn. Thanks so much for all help.David

 

[Derek Rowell]

Sorry, you cannot do that...

David, The answer is a definite "NO", you cannot connect the outputs from the GPS and the wind instrument together. I just took a look at the Navman manuals at www.navman.com. The multi and wind instruments have very limited NMEA outputs (and no input). On the other hand, your GPS will provide all the information for the autopilot, except apparent wind angle. Therefore unless you want to steer to the wind you simply need to connect the NMEA out from the GPS to the NMEA in on the autopilot. NMEA sends data as "sentences" - small packets of information, each dedicated to a particular function. For example, the "MWV" sentence specifies the wind velocity and direction, and this would be generated by your Navman wind instrument. I looked up the NMEA specs on the Standard-Horizon site for the CP150 GPS. It says that it recognizes the "MWV" sentence. Therefore I think there is a very good chance that your GPS would pass this sentence from its NMEA input directly to its NMEA output (I can't guarantee that of course!) Therefore to achieve full autopilot function you may be able to connect:1) The Navman 3100 wind NMEA out ---> CP150 NMEA in.2) CP150 NMEA out ---> WP30 NMEA in.Look at your GPS manual to see if there is any more information on the NMEA sentences that it recognizes.Derek

 

[David Underwood]

Wow, thanks Derek and Don.. but wait...

if there are more, just "come on into the forum". Really, thanks guys. Derek, think you put it in more straight forward terms than anyone I've talked to so far. Everyone understands... "NO".. right? Well I do. Ok, so what you suggested is that: the inputs from all the other Nmea "talkers" can send data into the chartplotter and what will come out is a total picture (that is their data plus the chartplotters data) of what the wp30 needs to function in the ways. You really have cleared it up for me so to speak. I really appreciate your taking the time to look this all up, but then again, I would/will do the same for you and anyone else here where I am able(got any photography questions?). Anyway thanks, and to anyone wanting to add to this, please do, I am still... "a listening device" David

 

[Chuck Wayne]

nmea

Derek's got it right-nmea devices are usually designed to daisy chain, and (usually!) will pass thru sentences, sometimes always and sometimes only if it's a sentence it understands- if you don't have literature that's specific, try it and see!

 

[Peter]

Milion dollar question re GPS data output

Does a GPS output data only in NMEA format? My current setup has a Raymarine tillerpilot and handheld remote. I'm about to wire the GPS to the tillerpilot as well. The tillerpilot socket has terminals for both NMEA and SeaTalk. I have the correct wiring harness but no manual for the GPS (Magellan handheld). I'm willin to try both sets of terminals on the tillerpilot socket but I'm afraid I might accidentally fry some circuitry in the process. Any suggestions? Thanks in advance.PeterH23 "Raven"

 

[Derek Rowell]

NMEA only

Peter, Your Magellan GPS will not have SeaTalk output. This is a proprietary hardware and data format found only of Raymarine/Raytheon/Autohelm instruments, and is incompatible with NMEA signals. You should connect your GPS data only to the NMEA in port on your TillerPilot and ignore the SeaTalk input.Good luck,Derek