NMEA networking

[Ralph18414]

I just bought a new ST2000+ tiller pilot for my old Pearson Wanderer and I would like to establish an NMEA network to interface it with so that I could stream data from the labtop (MapTech Offshore Navigator), Navman wind instrument, and the Simrad depth/speed instrument. After searching the web, the sailboat owners archive, and multiple chats with Raymarine Tech support, I think I know how to make a connection to a single device at a time. However, it is not apparant to me how to connect or daisy chain multiple devices together. Can anyone provide a link or some sage advice? At times like this I am truly grateful for the collective knowledge of the many fine sailors here.

 

[Nice N Easy]

For whatever it's worth

Ralph,For whatever it's worth I personally don't like to tie stuff together. I keep thinking that if one device should screw up, fail, quit working or whatever that they will all go with it. And there is really no major advantage to linking them all together, mostly a matter of convience. I have a wheel pilot that accepts NEMA input, and thought seriously about hooking it up to the chart plotter, but decided against it for that reason. Same with the radar. I know I am probably being anal, and most of this stuff is very reliable these days, but I still like each electronic item to be stand alone.

 

[Derek Rowell]

Can't do it easily...

Ralph,NMEA 0183 (not to be confused with NMEA 2000) is basically a one talker - multiple listener system, that is only one device can be designated as the sender of information. There is no "collision avoidance" of messages from multiple devices, such as in a Raymarine SeaTalk network.That said, you can buy a NMEA multiplexor that will take data from multiple devices on separate input connectors, and spit out a single NMEA stream of the individual "sentences" on its output port.Derek

 

[muised]

Unhelpful advice from me

I know this won't help in your situation, but if you buy any more seatalk compatible instruments, you can just connect all the data and ground wires and they'll talk fine (beats buying proprietary seatalk cables and junction boxes). I did this last spring before I spent any more cash, and my ST40 Wind, Bi-data, and RC400 chartplotter are getting along fine.

 

[Jadedcrew]

NMEA

Derek is correct, you will need a multiplexer to combine the 'talkers' into one stream. Assuming that all instruments are NMEA 0182/0183 talkers. I'm sure the wind is. Does the AP have a NMEA input (my ST400+ WP does but will not output NMEA)? Does it have Sea Talk output? Here is a link to a company that I bought from, but there are others. Just "Google" nmea multiplexer for a list of manufacturers. You will need at least 2 wires from the "talkers", 3 if they can listen. You can also tie in the NMEA from the gps. You will want a multiplexer that can convert Sea Talk to NMEA, because your AP will have some compass info that your Map Tech will want.

 

[Ralph18414]

Mick and others, thanks for the advice. While

googling the subject I didn't think of adding "multiplexer" to the search. Buying a multiplexer will be the way to go. This weekend, however, I'll hook up the laptop and wind instrument to the autopilot via a switch box I've constructed. I'll have to manually switch between the two. I am as exciteded as all get out because my boat is very uncomfortable to helm. Upgrading to wind steering is a big plus on the lakes of the Tennessee River--the wind always shifts the closer you get to a shore. Also, the wireless remote makes the addition of wheel steering moot. It is time to retire my old faithful Navico tiller pilot.BTW, the ST2000+ is a listner only--it doesn't talk.