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My Garmin GPSMAP 551 has 2 nmea ports. Port one is connected to a Raymarine course computer, port 2 'nmea out' feeds a dsc vhf. Can I connect the vhf port to a Nasa AIS engine as well , without affecting the gps feed to the radio?
Two Instruments using single nmea port?.
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sailorman
Well-Known Member
i have a furuno gp32 & raymarine nema connected via a block connector to within a water resistant box
nigelmercier
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One talker can talk to many listeners, but there can only be one talker.
pvb
Well-Known Member
Yes is the answer.
David2452
Well-Known Member
One talker but a maximum of three listeners is the official number, more sometimes will work, sometimes not.
[3889]
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So is PVB correct? The plotter can 'talk' to the vhf through the same port as it 'listens' to to the AIS?
David2452
Well-Known Member
No, 0183 ports are one way only.
nigelmercier
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And the Baud rates will be different on the AIS output, assuming this is what is meant.
Not enough info to be sure what is required.
Not enough info to be sure what is required.
pvb
Well-Known Member
I assumed you wanted to feed a GPS position to the Nasa unit. It will do this. If you're hoping to receive AIS data via what you obviously know is an "NMEA Out" port, you're going to be disappointed. Your original post was totally open to misinterpretation.
[3889]
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Oh dear.
To clarify, the plotter wiring loom includes 2 pairs of wires designated as nmea ports 1 & 2. One wire in each pair is marked 'nmea in' the other 'nmea out'. Only the 'out' wire on port 2 is used to feed the vhf - the 'in' wire is not connected to anything and my query is can an AIS engine deliver nmea input through this unused wire?
nigelmercier
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It depends whether the port can run at 4800 out/38400 in, probably not. What is port 1 doing?
Norman_E
Well-Known Member
Read the NMEA 0183 information sheet which you can download, its the last item on this page http://www.actisense.com/products/nmea-0183/ndc4/downloads-ndc4.html
If all else fails you can multiplex NMEA 0183 with the Actisense NDC-4.
If all else fails you can multiplex NMEA 0183 with the Actisense NDC-4.
pvb
Well-Known Member
Right, your Garmin 551 has 2 serial ports. Each can input or output NMEA data. NMEA data is transmitted at a set speed. Most equipment uses NMEA at a speed of 4800 baud; however AIS data is transmitted at a much higher speed of 38400 baud. Each of your ports can be set to 4800 (called "NMEA Standard" by Garmin) or 38400 (called "NMEA High Speed" by Garmin). You can change the speed of either port via the menu (Configure > Communications). But the speed is applied to both the input and output of the port - you can't have different speeds on the same port.
So, you'll need to configure one port to run at 4800 and one to run at 38400. The 4800 port can be used to output NMEA to your course computer and DSC radio. The 38400 port can be used to input the AIS data.
nigelmercier
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Quite so, that is where I was going.
I do wish that people asking questions would give the details of the gear they are using, "Garmin 551" means nothing to me unless I look it up.
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OK, thanks PVB and for all other technical input. Nigel, not sure what you mean by details of gear; it is a Garmin GPSMAP 551 as stated in the original post. If I understood the intricacies of NMEA I wouldn't have asked the question.
nigelmercier
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A fair point. Looking back at your OP perhaps you did try to give all the info. I find that a diagram is useful when asking a question of this type.