GPSMAP 750/Raymarine ST60 compatibility?

Troubadour said:
I think only distress shows automatically but you can force a position display from a logged DSC call.
I don't think your concern about the ST4000 is right. Like the multi and the graphic it takes NMEA input and puts it onto the ST bus to share. Raymarine have told me only one instrument in a system should have an NMEA input to avoid confusion but obviously it needs the ST connected to share it.

Superheat6k should be able to help you more than me!
Click to expand...

I haven't connected the DSC data NMEA out from the RO4800 VHF to the Garmin. If I receive a Mayday to pass on I will plot it manually from the dsc data on the screen if the VHF set. I figured this would be a rare event, but did want to see practical live data such as log speed and depth on the Garmin.

I couldn't find any good way of splicing the various data cables together directly, so came up with the idea of a sealed box with a chocolate strip, separate plugs and sockets. These are 2 pin for Seatalk, 6 for the Garmin & 8 for the RO4800, so they can't be muddled. Soldering the 8 pin was to say the least fiddly.
 
Today I've confirmed the continuity of my wiring from the Raymarine multi NMEA output to the the Garmin 750, and with a multimeter confirmed that the multi is outputting something every two seconds as it should; the meter shows a very definite blip.
However the Garmin diagnostics page says no, I'm not receiving anything.
So what next?

superheat6k - I'm not quite clear, are you going direct into the 750 with NMEA output from a Raymarine instrument or are you using the Seatalk/NMEA converter box? Any problems?

Re the claims that Raymarine's NMEA output is not really NMEA, isn't that charge levelled against Garmin just as often? But the Raymarine instruments and the Skanti DSC radio happily accept the Garmin output.

NMEA doesn't look a complicated standard or protocol - surely it is NMEA or it isn't?

Further suggestions much appreciated...
 
Troubadour said:
Today I've confirmed the continuity of my wiring from the Raymarine multi NMEA output to the the Garmin 750, and with a multimeter confirmed that the multi is outputting something every two seconds as it should; the meter shows a very definite blip...
Click to expand...

Are you able to put a figure on the voltage?

It's times like this that I'm glad I have an oscilloscope on-board. Just found this, astonishing at the price:
http://www.amazon.co.uk/exec/obidos/ASIN/B006CQT49E/dolcetto-21

[EDIT]

Or you could build one: http://tomeko.net/miniscope_v2c/
 
Last edited:
nigelmercier said:
I'd bet money it is a voltage level problem. Can you borrow an oscilloscope?
Click to expand...

I could more easily make a resistive divider to try if you reckon it's a 12V/5V problem. What sort of values? No idea what Z and i NMEA operates on.

BTW I've also connected the NMEA output of my DSC radio to the Garmin's other input port. Would you expect that only to transmit when it has something to say or should it give an idented but empty string all the time? The 750 also says no DSC sentence received.

I'm going to put questions to Garmin and Raymarine support - I've found them both very responsive previously. I think trying to get any Skanti support from Cobham Globalsat is probably a dead duck.
 
Troubadour said:
I could more easily make a resistive divider to try if you reckon it's a 12V/5V problem. ...
Click to expand...

But in this case the suspected voltage difference is going the wrong way, isn't it? In other words it may need to be increased. I would borrow an oscilloscope, or buy a cheap one.

The one I have on-board is below, it's also a very good multimeter:
http://www.ebay.co.uk/itm/UNI-T-Dig...ols_Levels&hash=item23298651db#ht_1235wt_1057

You can also get them cheaper if you don't mind waiting for China Post:
http://www.ebay.co.uk/sch/i.html?_o...l1313.TR0.TRC0&_nkw=(ut81B,+ut-81b)+&_sacat=0

Alternatively, you could try this to give you an idea of the values:
http://www.zen22142.zen.co.uk/Prac/winscope.htm
 
Last edited:
I wouldn't bet money on the Multi outputting all of the NMEA that the spec. claims.
I have an ST60 Graphic, fairly similar to the Multi AFAIK. I used its NMEA output for HDM to enable Furuno radar plotting on my Yeoman. The HDG data originated on Seatalk from my ST60 Compass. Worked fine. Then I found that when I connected up an ST4000 Tillerpilot, some of the Graphic NMEA output, including HDM sentence, disappeared. I confirmed this on a PC.
Raymarine couldn't explain this, but agreed that it did happen going so far as connecting up their own system to test it. Their response was to offer me their NMEA/Seatalk interface box at a very good price. This works well.
In summary:- 1) Graphic NMEA conversion is useable when it happens; 2) Don't rely on it.
 
earlybird said:
I wouldn't bet money on the Multi outputting all of the NMEA that the spec. claims.
I have an ST60 Graphic, fairly similar to the Multi AFAIK. I used its NMEA output for HDM to enable Furuno radar plotting on my Yeoman. The HDG data originated on Seatalk from my ST60 Compass. Worked fine. Then I found that when I connected up an ST4000 Tillerpilot, some of the Graphic NMEA output, including HDM sentence, disappeared. I confirmed this on a PC.
Raymarine couldn't explain this, but agreed that it did happen going so far as connecting up their own system to test it. Their response was to offer me their NMEA/Seatalk interface box at a very good price. This works well.
In summary:- 1) Graphic NMEA conversion is useable when it happens; 2) Don't rely on it.
Click to expand...

Bit flaky then!
I'm not getting anything though - should have DBT, HDG, HDM, MTW, VHW, MWV.
I could try disconnecting the ST4000 but it means opening up the helm pod AGAIN!!
 
Found an interesting thread of someone having a related problem http://www.boatbanter.com/showthread.php?t=38711

Starts with this

"I have a Raymarine ST60 Multi and want to get NMEA data (Wind & Depth) into
the 9 pin serial port on my laptop. If the laptop is not connected to
anything at all (including power supplies) this works fine. If I connect it
to the boats 12v supply via a cigarette type laptop power supply, or an
inverter using the normal laptop power lead I get nothing."

and ends

"First the good news

Cracked it

The so called NEMA output from a Raymarine Multi should be floating, but the
positive terminal is at 12v; something to do with being able to use the NMEA
out terminals for an alarm. This as it were "shorts out" the RS232 on the
laptop

Now the bad news

You need a RayMarine PC/SeaTalk.NMEA Interface (E85001). Cost about £100.
Yet another RayMarine Con, but it solved the problem."

Does this mean the problem is because Garmin (like many others) tie the NMEA - line to power ground instead of having a floating differential input?
Is there a workaround (for less than the Raymarine interface)?
 
Troubadour said:
Misunderstood your #20 then, thought you meant Ray use 12V and others use 5V.
Click to expand...
Sorry, that is what I meant. I've obviously got confused.

Troubadour said:
Will an under £2 ebay RS232/USB adapter with a PL2303 chip in it do the job?
e.g. http://www.ebay.co.uk/itm/USB-2-0-T...t=UK_Computing_USB_Cables&hash=item2578bcddd6
Click to expand...

I have bought several of these cheap ones over the years, I have yet to find one that doesn't result in a BSOD from the drivers every few hours.

Troubadour said:
Does this mean the problem is because Garmin (like many others) tie the NMEA - line to power ground instead of having a floating differential input? Is there a workaround (for less than the Raymarine interface)?
Click to expand...

If that is the problem, then yes: an opto-coupler. Can you draw a plan of how you want to connect them, in text if you like.
 
Last edited:
View attachment 31263
nigelmercier said:
I have bought several of these cheap ones over the years, I have yet to find one that doesn't result in a BSOD from the drivers every few hours.

If that is the problem, then yes: an opto-coupler. Can you draw a plan of how you want to connect them, in text if you like.
Click to expand...

Occasional BSOD no problem it was just for diagnostics!

On your Dolcetto website you have the ST60 multi service manual with cct dia in it :-)
I don't fully understand it - my electronics was analogue, never got to grips with digital - but the NMEA+ out is regulated at 11.2V with an 80mA current limit. I don't quite see what the - does to it. There is a test procedure too.

Very nasty drawing below
edit - oops above!
of what I have set up - maybe too nasty.
Plotter feeds nav data to the multi NMEA input that translates it onto SeaTalk bus. This works.
Multi NMEA output should feed translated ST data (wind, depth etc) to plotter. Doesn't work.
Plotter (2nd port) feeds nav data to DSC. This works.
DSC should feed alert position to plotter. Don't know if it works but bet it won't because Skanti did everything in it strictly to standards (e.g. the only time input it will accept is ZDA - rare except in commercial equipment) so unlikely to accept the unbalanced termination I suspect.
 
I have just tried connecting the 750 NMEA output to the ST4000 and I now see the expected waypoint and course data on the Autohelm display. There doesn't seem to be an issue with "data looping".

Still no DSC info showing on the 750. I looked at the diagnostics and it shows "Not received" for DSC and DSE. I'm waiting for someone to press their Distress button, but of course hoping nobody does.
 
Last edited:
I have an ST60 Tri data+ this has a separate NMEA output connection, the Tri data internally converts the Seatalk to NMEA format.

I don't have a separate mux. The Garmin picks up the speed and depth sentences just fine. I don't have a temperature logging speed transducer so my Tri only has depth and water speed available to see. It will also have presumably the autohelm data stream messages too, but these would be of little interest to the Garmin.

When I had a similar problem with the lack of AIS data being shown at the Garmin I had a similar problem with working out if it was the Garmin receiving but not seeing the data, the RO4800 showing it locally but not sending it out, or that I had messed up the wiring connections.

This is why I made the 3 way junction box. Mine turned out to the RO4800, but yes this was a nightmare. If you are sure the NMEA signal is on the wires I would send back the Garmin for factory testing.

Or if you are near the Hamble you can bring it to my boat to see if it sees my Seatalk data on my Garmin connector. This would be a go no go test for he Garmin.

PM me if you want to take this up.


Troubadour said:
Today I've confirmed the continuity of my wiring from the Raymarine multi NMEA output to the the Garmin 750, and with a multimeter confirmed that the multi is outputting something every two seconds as it should; the meter shows a very definite blip.
However the Garmin diagnostics page says no, I'm not receiving anything.
So what next?

superheat6k - I'm not quite clear, are you going direct into the 750 with NMEA output from a Raymarine instrument or are you using the Seatalk/NMEA converter box? Any problems?

Re the claims that Raymarine's NMEA output is not really NMEA, isn't that charge levelled against Garmin just as often? But the Raymarine instruments and the Skanti DSC radio happily accept the Garmin output.

NMEA doesn't look a complicated standard or protocol - surely it is NMEA or it isn't?

Further suggestions much appreciated...
Click to expand...
 
superheat6k said:
I have an ST60 Tri data+ this has a separate NMEA output connection, the Tri data internally converts the Seatalk to NMEA format.
Click to expand...

Well mine certainly doesn't. It has 2 SeaTalk ports, depth transducer and speed transducer connections. No NMEA in or out.
AFAIK only the multi and the graphic have NMEA out. The ST4000+ has NMEA in but not out.
:confused:
 
You must log in or register to reply here.

Share this page

Top