GPS connection to DSC VHF radio

[Iocus]

I have a Silva Star M-55 DSC VHF and a Garmin GPSmap 76 and want to connect the Garmin so it can send the Lat & Long position to the VHF radio. I have the correct connector for the back of the Garmin 76CS (12v cigarette connector and two spare wires, white and brown). The radio has two wires for GPS, blue and brown. Unfortunately the VHF radio does not have a manual and none seem available on the Internet. Silva can't help either. It appears to be simple, just join the wires but after trying both combinations along with altering the interface options on the Garmin the radio would not display the Lat & Long automatically. Can anyone help or does anyone have a manual for the Silva Star M-55 DSC VHF radio? Thanks

 

[misterg]

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Can anyone help ....

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Only to point out that the output from the GPS is between the brown wire and ground (black wire). The white wire is data in to the GPS, and can be ignored.

Just for completeness, the interface settings on the GPS need to be set to NMEA/NMEA, with the baud rate 4800 (default).

On the Silva S10, the GPS input + is red / input - is black, but I've no idea whether this is consistent across the range.

Andy

 

[saxonpirate]

I think you'll find that you have to go into your main menu on your GPS and select interface and make sure you have NMEA data output set up. If you have a manual for your GPS it should point you in the right direction.

I have a Navman DSC linked to a Garmin 128, and although it's a long time ago, I'm pretty sure this is the procedure I followed. I've put a link below to what I think is your radio. It's a PDF file Owners Manual. Hope you succeed.

http://www.icom.co.jp/manual/external/transceivers/IC-M55.pdf

 

[saxonpirate]

Just seen Andy's post and the interface setting he mentions jogged my memory. Have just checked on my Garmin 128 interface settings and he's spot on. Just in case you don't have a Garmin GPS Map 76 manual, here's another link to a PDF file.

http://www.tramsoft.ch/downloads/garmin/gpsmap76_users-guide.pdf

 

[misterg]

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... he's spot on. ...

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I know /forums/images/graemlins/tongue.gif

The only unknown is the identity of the wires from the VHF, but it's worth the OP trying them both ways round now that (s)he knows that the output from the GPS is the brown wire & ground, not the brown & white wires /forums/images/graemlins/cool.gif

(The more answers, the merrier as far as I'm concerned, btw.)

Andy

 

[Iocus]

Thanks for that. I hadn't joined the two common wires (ground) from the garmin and the Silva so that would appear to be why it didn't work. Will try it when I get back on my boat and let you know. Many thanks for your help.

 

[Iocus]

Thanks for the two links, I do have the Garmin Manual but unfortunately the IC M55 is not the same as my Silva DSC VHF but thanks for the help.

 

[misterg]

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Thanks for that. I hadn't joined the two common wires (ground) from the garmin and the Silva so that would appear to be why it didn't work. ...

[/ QUOTE ]

That's not quite what I'm getting at, if you'll bear with me:

The NMEA signal between the GPS and the VHF needs a (+ve) and a (-ve) signal. The Garmin GPS cheats a bit by combining all it's NMEA (-ve) signals with the 12V ground. The VHF *probably* doesn't, so one of the wires from your VHF needs to be connected to the brown wire from the GPS: NMEA out (+ve), and the other needs to be connected to the GPS ground which is also: NMEA out(-ve).

Hope this helps,

Andy

 

[babbot]

Its correct to join the common nwires from the radio and the GPS. In fact they will already be joined via the batteries -ve terminal. The only other thing you need to do is join the brown wire from the GPS to the data input on the radio.

As you say, without the radio manual that is going to take a little experimentation.

There is a useful diagram on the Icom site http://www.icomuk.co.uk/getFile.asp?categoryID=3813&cCID=5755&fFID=381

 

[PuffTheMagicDragon]

Good diagram.The OP, however, should note the little box in the centre of the diagram where it says :

<span style="color:blue">"The GPS will require setting to the NMEA interface mode
(normally NMEA 0183 v2.0 at 4800 baud)
The GPS can supply NMEA data to upto 3 NMEA devices.
Garmin GPS’s use a common ground for power and data;
the NMEA device may have a separate ground for the NMEA"</span>

 

[Iocus]

It appears that part of the problem was that I was running the GPS from its own batteries and not connected to the boats 12v system in any way. So it would appear that all I have to do is run the Garmin from the same 12V system as the radio, connect the brown wire of the Garmin to one of the GPS wires from the radio and the other wire of the radio to the negative of the 12v system and trying it the other way round if the first combination fails to work. Fingers crossed and thanks to everyone for their assistance/advice.

 

[Iocus]

PS, I'm a 'he' /forums/images/graemlins/grin.gif

 

[misterg]

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PS, I'm a 'he' /forums/images/graemlins/grin.gif

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I've learned not to assume /forums/images/graemlins/smile.gif

Andy

P.S. if you run both wires from the VHF to the GPS connector, the communications will work whether the GPS is on 12V or its own batteries.

 

[Refueler]

[ QUOTE ]
It appears that part of the problem was that I was running the GPS from its own batteries and not connected to the boats 12v system in any way. So it would appear that all I have to do is run the Garmin from the same 12V system as the radio, connect the brown wire of the Garmin to one of the GPS wires from the radio and the other wire of the radio to the negative of the 12v system and trying it the other way round if the first combination fails to work. Fingers crossed and thanks to everyone for their assistance/advice.

[/ QUOTE ]

No need to power from same source if you connect grounds of radio to GPS ground ... As long as you don't connect to + power of the separated item as well - you'll have no error in the grounding.

Personally I connected my radio to a RS232 socket and mounted that next to radio - means I can now connect any GPS that has RS232 plug to provide NMEA data to radio.

 

[Iocus]

I have tried every combination now and no joy. I think the radio GPS connection must be faulty as it doesn't read the data from the Garmin and the only way I can put the Long and Lat into the radio is manually and that then disappears once the power is turned off but it does remember the date and time but as I don't have a manual for the radio, and neither is there one on the internet that I can find, I don't know if there are any commands required to get the radio to acknowledge connection to the Garmin. Anyone else got any other thoughts?