NMEA 0183 head scratcher

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Plevier

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Present system is Raymarine Classic C70 plotter, ST60+ instruments, ST6002 a/pilot, Ray 240E DSC radio, EasyAIS receiver.
Everything works on SeaTalk except NMEA0183 AIS input to the C70.

Looking at replacing the C70 with a Lowrance. Unfortunately this only has 1 NMEA 0183 port and Rx and Tx have to be at the same rate. This will have to be high rate for the AIS.

To get instrument inputs into the plotter I can get a low rate NMEA out from the ST60+ graphic and the EasyAIS will bridge this onto its high rate output.

However to feed info from the plotter into the NMEA in of the ST60+ it needs to be low rate. I may also need to take this to the radio but I think the ST60+ will bridge it onto the SeaTalk and it will reach the radio that way.

So how do I turn a high rate NMEA into low rate (at reasonable cost)? Angus's YAPP only goes from low to high. :confused:

Afterthought - alternatively converting NMEA high rate to SeaTalk would do if that's easier, but I'd rather have NMEA in case of future change of the radio..
 
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Probably the easiest and cheapest solution would be to buy a standalone GPS receiver to feed position data into the radio, etc. The Evermore SA320 is often recommended, about £70. This also introduces some redundancy in case the plotter were to fail.
 
pvb said:
Probably the easiest and cheapest solution would be to buy a standalone GPS receiver to feed position data into the radio, etc. The Evermore SA320 is often recommended, about £70. This also introduces some redundancy in case the plotter were to fail.
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Thanks. That would be a solution for the DSC but it would rather limit the instrumentation wouldn't it - no waypoints, XTE etc.
 
Plevier said:
Thanks. That would be a solution for the DSC but it would rather limit the instrumentation wouldn't it - no waypoints, XTE etc.
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I think Pete may have meant that you wire up your system as per your original post but instead of taking the GPS from the C70, take it from an SA320.

I.e. ST60+ Graphic NMEA -> 4800 -> EASYAIS -> 38400 -> C70 .

Also run SA320 NMEA -> 4800 -> ST60+ and chain to (if required) VHF GPS In.

Hth,

Boo2
 
Plevier said:
Yes it would - and a lot more besides!
Only snag is the cost. The plotter is an opportunist buy at bargain price, not planned - putting another £180 on rather takes the shine off it (and might lead to strife with the Financial Director!)
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But it does work well. I have the same network structure as you except for SH matrix AIS/VHF (without gps). Installed the actisense this winter and all is good including PC connection and wifi out to iPad. Uncle Tom Cunliffe says that AIS is as important a contribution to safety as the life jacket. Therefore the FD can't object. Good luck.
 
Boo2 said:
I think Pete may have meant that you wire up your system as per your original post but instead of taking the GPS from the C70, take it from an SA320.

I.e. ST60+ Graphic NMEA -> 4800 -> EASYAIS -> 38400 -> C70 .

Also run SA320 NMEA -> 4800 -> ST60+ and chain to (if required) VHF GPS In.

Hth,

Boo2
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Hi Mike

No, that only gives position, COG and SOG to the instruments and autopilot; waypoints, XTE, BTW, DTW have to come from the plotter, a separate GPS wouldn't know them. (Where you say C70 substitute Lowrance; with the existing C70 it does all work over SeaTalk.)
Would welcome any ideas if I see you at Southwick though. Have you done all your nav gear yet?

Mike
 
cliveshelton said:
But it does work well. I have the same network structure as you except for SH matrix AIS/VHF (without gps). Installed the actisense this winter and all is good including PC connection and wifi out to iPad. Uncle Tom Cunliffe says that AIS is as important a contribution to safety as the life jacket. Therefore the FD can't object. Good luck.
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I like it but 2 snags:
1 With the existing C70 it all works including AIS - but I fancied this wizzy plotter with a bigger screen and that should update acceptably quickly - the C70 is soooooo sloooooooow with recent big file size charts.
2 FD doesn't sail and might prefer to think about the life insurance! (Only kidding.)
 
pvb said:
So have you actually bought the plotter? Your OP suggests not.
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Yes, but seller is happy to take it back - he made a mistake in telling me it had 2 ports. Only discovered the problem when it arrived this morning. (The previous pushbutton version did have 2; the touch version only has 1. He wasn't aware.)
 
OK, well you certainly need a multiplexer if you're going to make full use of it, and that's the thick end of £200. It might be worth sending it back and looking around for an alternative. The plotter market is changing rapidly, so there'll always be bargains to be had on models which have been superceded.
 
Plevier said:
No, that only gives position, COG and SOG to the instruments and autopilot; waypoints, XTE, BTW, DTW have to come from the plotter, a separate GPS wouldn't know them.
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Hi Mike,

Good point, as you say you need to feed back the output from the plotter into the systems for XTE etc to be available to the instruments.

Plevier said:
Would welcome any ideas if I see you at Southwick though. Have you done all your nav gear yet?
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I'm just off up there now as a matter of fact, just got to put on the genoa and re-stick my headlinings then I'm off down to Langstone.

I solved all my nav gear issues (except one that I think is the radios' fault) by the simple expedient of throwing money at the problem :p (In the name of a Raymarine ST to STng adaptor). I do now have a system with bot ST and an STng backbone to the chart table as well as SThs nicely positioned ready for a radar in the event that funds become available...

Boo2
 
Plevier said:
So how do I turn a high rate NMEA into low rate (at reasonable cost)? Angus's YAPP only goes from low to high. :confused:

Afterthought - alternatively converting NMEA high rate to SeaTalk would do if that's easier, but I'd rather have NMEA in case of future change of the radio..
Click to expand...

To answer this directly... if I'm understandig corectly... you can't convert high to low rate or to SeaTalk-1.... it's high rate in order to be give sufficient bandwidth for the AIS data.

Though thinking about it more - presumably the AIS data won't be output on that port... only the GPS data. So a circuit with a suitable buffer might be enough. Worth seeing if Angus could re-write the PIC code a little, assuming the PIC has enough RAM to act as a reasonable buffer in case of a sudden burst on the high speed connection.

Does the new plotter have an NMEA2k port on it?

If so... http://www.cactusnav.com/actisense-ngw1-nmea-gateway-p-10294.html - cheaper than the multiplexer. Not by a lot once you've setup a NMEA2k backbone though.
 
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yachtailsa said:
To answer this directly... if I'm understandig corectly... you can't convert high to low rate or to SeaTalk-1.... it's high rate in order to be give sufficient bandwidth for the AIS data.

Though thinking about it more - presumably the AIS data won't be output on that port... only the GPS data. So a circuit with a suitable buffer might be enough. Worth seeing if Angus could re-write the PIC code a little, assuming the PIC has enough RAM to act as a reasonable buffer in case of a sudden burst on the high speed connection.

Does the new plotter have an NMEA2k port on it?

If so... http://www.cactusnav.com/actisense-ngw1-nmea-gateway-p-10294.html - cheaper than the multiplexer. Not by a lot once you've setup a NMEA2k backbone though.
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Correct, no AIS on it.
Yes, I'm sure that genius Angus could solve it in a few minutes!
Yes, it does have 2k - and 2 ethernet ports - but only one 0183. Obviously nobody wants 0183 now, my dear, it's so yesterday!!
But no, I don't want to go into setting up a 2k backbone just to overcome this.

Have to tolerate the C70 a bit longer I guess.
 
I'm guessing you were perhaps looking at a 9" plotter. Have you considered the Raymarine a95? This has two NMEA0183 ports - one is input only and can be set to 38400baud for AIS, the other is input and output and can be set to 4800baud. The SeaTalk port is SeaTalkng but you can get a converter if you want to use your old SeaTalk connection.

I think we are seeing a steady move away from NMEA0183 connectivity on MFDs, so if you want to keep using the rest of your system, it might be better to upgrade your plotter sooner rather than later. At £1040, the a95 probably costs about the same as the Lowrance with a multiplexer.
 
Plevier said:
Thanks. That would be a solution for the DSC but it would rather limit the instrumentation wouldn't it - no waypoints, XTE etc.
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How are you feeding GPS to the lowrance???? If using the lowrance GPS antenna then this gives waypoints etc on the plotter via the 2000 port. Isn t the other port using the bare end data cables in the power assembly a different one and this can be set at 34000 ???? There is a man in Torquay who knows all this stuff....Any one know him...He sells Evermore.
 
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