General NMEA0183/NMEA2K, DCS, MMSI questions

[sailah]

I've been working a bit more with my electronics in trying to get them talking together.

Here's what I have:

Garmin 942XS at helm. Networked to Raymarine ST60+ instruments via SeaTalk converter, NMEA2K, works great, get all my sailing info on Garmin

Garmin 3206 w/Radar. This was old helm chartplotter but since radome would not have worked with 942, I moved to underneath cockpit seat to retain radar functionality and backup chartplotter.

Garmin 440 chartplotter at Nav. This is a standalone chartplotter, rarely used. Has its own Garmin 17 antenna.

Icom M502-Old VHF but still works great. I acquired MMSI yesterday and verified it does not have one programmed so I plan on doing that today.

Simrad AP11 autopilot. Finally connected to blue/gray NMEA1083 of 942XS to get route information, XTE

My plan is to connect Icom VHF to NMEA1083 of 942xs to enable DCS. I was going to do this by paralleling the blue/grey wires of Garmin. Good idea? I presume the output sentences of the Garmin to Simrad and Icom would be compatible?

Is there any benefit to connecting the Garmin 440 to the 942xs? Clearly this would be connecting via NMEA1083 to the 942XS. The nav station is custom built around the 440 and I'd prefer to not hack it up, although clearly having a NMEA2k chartplotter would be ideal.

I was planning on using some direct burial CAT5 cable to run the NMEA0183 connection between Garmins. I have 1000' spool here and don't see why it wouldn't work. Since I have 4 twisted and shielded pairs, if I was to hook things up, now is the time to connect the 440 when I have everything apart.

I would very much like to get the old 18" garmin radome to talk to my 942XS and get rid of that entire setup but it looks like the only option is a new radome. I rarely use radar anyways so I felt like this was best option.

[Hartleyg]

Hello Sailah,


I'm not a Garmin expert at all, but I have messed with NMEA-0183 & N2K.


I don't know if that color code is the NMEA0183 output (AKA "talker") from the chartplotter, but if it is, you should be able to connect it to multiple NMEA receive ("listener" ports NMEA0183 uses one pair for data in each direction, so you need to be careful to have one sender in any hookup - multiple receivers is fine.
The "normal" wire folks use for NMEA0183 is the olde 4-wire "jake" telephone wire - your CAT5 cable is overkill, but should work fine
I doubt there is a way to hook your old radar to your newer plotter - radar requires a high-speed connection (an order of magnitude faster than N2K) so unless the radar and the plotter share such a port, it likely won't work.
The only negative with hooking two chartplotters together is they might get confused as to which GPS input to use - make sure you program them properly.


Hope this helps!


Hartley

[smac999]

I have used some pretty old Garmin radars on new screens. Have you tried?

Gps data can be split to ap and vhf. Fine.

I probably would not bother to hook up the 2 Garmins.

[sailah]

Thanks Hartley,

The plan is to have the 942xs as the talker since that's on 100% of the time. I debated using the smaller 440 as the GPS input since it's 4" away but that would mean that I would need to have it on for DCS to work. Rather spend a bit more time to run the wire. Hopefully it all works on first go. My only concern was having to change the sentences and it adversely affects teh autopilot which I don't want to do.

I'm thinking I agree with you regarding connecting various GPS together. The 942XS is a much nicer unit and probably has a more accurate GPS anyways. I only use the 440 for generally looking at things when at anchor at my nav anyways. The 942xs will output to my iPad over wifi which we can argue is far more useful anyways.

The CAT5 cable I have is really nice and slick and pulls very well. It's 24g solid wire so it should do fine.

Eventually I'll get a new radome but I seem to rarely use it so it's not a priority. Seems too bad there is no way to get the radar signal on the 942 clearly a cash grab by Garmin

[sailah]

Originally Posted by smac999

I have used some pretty old Garmin radars on new screens. Have you tried?

Gps data can be split to ap and vhf. Fine.

I probably would not bother to hook up the 2 Garmins.

I have not tried yet, don't even know where to start. I just got the mast up and connected the wires. All I know is that Garmin says the radome is not compatible. Would be awesome if it were?

Hmm, on consulting Garmin website, it appears that my unit GMR18 is in fact compatible. That's fantastic. Will set about getting my RJ45 crimping tools in order and see if I can in fact get this unit up and running. I swear I looked on Garmin discontinued site to check compatibility and it was not listed. Maybe it took them a year to update.

Thanks for making me check!

[smac999]

the other option is feeding the vhf from the 17 antenna. just split the wires to the vhf and the 440 (at the back of the 440) which is nmea 183 to the plotter. wire so the 17 always has power (probably need to hardware (ground) the orange control wire) , and will always feed the vhf. and you can turn either plotter off and on as needed. this will give you gps 100% of the time. because I'm sure both plotters will be off sometimes too. and no wire to run

[sailah]

OK so made some good progress and some not so good.

I managed to connect the right wires (blue/grey) from the 942XS to the VHF. Got MMSI programmed and VHF is now displaying correct GPS coordinates.

However before I did that, I wasted 3 hours trying to connect the Garmin GMR18 radome to the 942XS. It certainly seems possible to do as the new Garmin has same ethernet connection as old 3206. Here's where the problem is:

I cannot figure out the Ethernet wiring from radome. I connected it as I had to the 3206, nothing. Doesn't show up as one of the networked devices on either chartplotter. It did last year or last time I checked.

The wiring used to connect to the chartplotter with terminal blocks but I redid that with an RJ45 connector last year and I swear it works. I have power going to radome.

I hooked it up according to standard CAT5 connection T568B:

Orange/white
Orange
Green/white
Blue
Blue/white
Green
Brown/white
Brown

When I check with my cable tester, I get pings on 1, 3, 5, 6, 8
When I check chartplotter, I get pings on 2, 5, 6

I'm getting about 0.25V on each pair if that means anything.

I tried almost every combination possible thinking I need 2, 4, 7 to match the radome (?)

Anyone know the correct pinout for this wiring? I hope this is all it needs.

https://www.youtube.com/watch?v=PF-c5ehjUVs&t=3s

[sailah]

And if I only I had thought to search Google...

Back to the boat tomorrow to try with this handy cheat sheet

[smac999]

garmin uses cross over cables

[sailah]

Originally Posted by smac999

garmin uses cross over cables

Why couldnt you have teleported into my brain in hour 1 with this useful information?

[sailah]

To finally put this to rest, i ended up having to go up the mast and check the cable with my cable tester. Pins 6&8 were reversed somehow and the cable was configured as a patch vs crossover. I plugged a good ethernet crossover directly into radome and my chartplotter, worked instantly. Made the corrections to the garmin network cable and crimped on a new RJ45.

Radar works great and very pleased to have it working on main plotter.

Total pain to track down though.

The Greenlee Datashark ethernet cable tester wasnworth its weight in gold today as i don't know how i ever would have found the issue without it.