VHF DSC not talking to GPS - help please

[Ross D]

I am currently completely re-wiring my boat and cannot get the GPS to talk to the VHF DSC.

I have a Garmin GPS 72 and a Navman 7100 VHF.

I have wired the connections as per the link:

http://www.plastimo.com/pdf/VHF_GPS_interface_en.pdf

But the VHF still states "No GPS", any ideas on how to sort it out?

When I bought the boat the VHF was wired to the chartplotter, and again had the same problem of "No GPS" the wiring seemed okay but I assumed it was at fault as most of the connections onboard were knackered hence the complete re-wire.

I am connecting it to the small GPS as the chartplotter draws 1.5 amps so we only turn it on when we need to know where we are. For most cruising you can look out of the cockpit and have a rough idea of where you are and where you're going, the chartplotter simply makes me lazy.

 

[prv]

The connections may be fine; you also need to make sure the GPS is transmitting, and if so that it is transmitting in a format that the VHF is expecting. Older Garmin GPSes had a proprietary mode which I think may have been the default unless you changed it to NMEA - check your manual. There may also be a choice of speeds (in baud) - again, find a setting that both GPS and VHF have in common and then make sure they're both set to it.

EDIT: Just followed your link. I assume you've looked up the actual colour for NMEA-out on a GPS 72, and didn't just pick white because that's what the Plastimo device in the diagram uses? There's no standard for these colours as far as I know.

Pete

 

[Playtime]

I assume you've looked up the actual colour for NMEA-out on a GPS 72, and didn't just pick white because that's what the Plastimo device in the diagram uses? There's no standard for these colours as far as I know.

Pete

I believe the GPS Data Out lines are brown and black (but double check with the Manual or any info that came with the cable). White is generally Data In (not Out) for Garmin GPSs.

The GPS Interface should be set to NMEA and speed is 4800bps.

I don't think you need to change anything at the radio end.

 

[johnalison]

It may not be relevant to yours but my DSC set wouldn't accept the GPS signal until I reduced the Baud rate one step.

 

[martin.53]

I had a similar problem trying to get my 7200 speaking to my Furuno GPS. Turned out the wiring diagram in the manual was wrong. Two colours the wrong way round. Not seen your wiring diagram before though.

Sorry can't remember which were wrong. My notes at home are no help. My son sorted it out by speaking to Navman/Plastimo directly in France.(English speaker).

 

[prv]

It may not be relevant to yours but my DSC set wouldn't accept the GPS signal until I reduced the Baud rate one step.

Do you mean reducing both sides? If so it sounds like maybe dodgy wiring that's dropping bits at higher speeds - although if it works reliably at the lower speed then that's pretty much academic. A good thing for the OP to try, perhaps, if his current speed settings are very high.

If you mean just changing one end, then that's simply making sure that the two devices are using the same settings, as already mentioned.

Pete

 

[pvb]

I had a similar problem trying to get my 7200 speaking to my Furuno GPS. Turned out the wiring diagram in the manual was wrong. Two colours the wrong way round. Not seen your wiring diagram before though.

Sorry can't remember which were wrong. My notes at home are no help. My son sorted it out by speaking to Navman/Plastimo directly in France.(English speaker).

Some Navman sets had incorrect instructions, but the diagram linked to by the OP is correct (yellow=NMEA+, green=NMEA-).

 

[pvb]

It may not be relevant to yours but my DSC set wouldn't accept the GPS signal until I reduced the Baud rate one step.

The Navman 7100 requires data at 4800 baud.

 

[SAMYL]

I think your Plastimo diagram is incorrect for a Garmin unit.
If I remember correctly the data-out from the Garmin has to be connected to ground (-ve), join them together then feed that to your radio data-in connection. This applies to Garmin units only.
I will check this when at my boat on Saturday, I don't have the info at hand just now.
There should only be three wires of interest from the Garmin, +ve, -ve, and data-out. As I said before join -ve and data-out together.

 

[Playtime]

There should only be three wires of interest from the Garmin, +ve, -ve, and data-out. As I said before join -ve and data-out together.

No!

Garmin 72 Manual Page 48 is quite clear - use the brown (Data Out) and black (ground) wires and connect to the yellow and green on the Navman respectively i.e. green to black, yellow to brown.

Speed 4800.

 

[pvb]

I think your Plastimo diagram is incorrect for a Garmin unit.
If I remember correctly the data-out from the Garmin has to be connected to ground (-ve), join them together then feed that to your radio data-in connection. This applies to Garmin units only.
I will check this when at my boat on Saturday, I don't have the info at hand just now.
There should only be three wires of interest from the Garmin, +ve, -ve, and data-out. As I said before join -ve and data-out together.

Completely, totally, utterly wrong! The Garmin data out (brown wire) connects to the Navman NMEA+ (yellow); the Garmin ground (black wire) connects to the Navman NMEA- (green).

 

[prv]

No!

Agreed, grounding the NMEA +ve is clearly nonsense.

Pete

 

[Topcat47]

My Cobra is sensitive to the version of NMEA output by the GPS (the Cobra is new, the GPS not). There is one version o/p by the GPS which the Cobra can read but it's not compatible with my navigation computer software. I don't know if this problem is common amongst DSC Radios but it might be worth checking.

 

[ostell]

Had a Garmin handheld and Navman on the last boat. They do work together providing the Garmin is set to the speed the Navman accepts.

The confusion in the wiring is that the Garmin NMEA -ve is also the supply -ve so the NMEA -ve on the Navman has to be connected to the -ve supply with (of course) the NMEA +ve connected together. This presumes that you are powering your Garmin from the boat battery.

A few people have had problems with this.

 

[SAMYL]

OK OK I was totally wrong. Apologies to Playtime, PVB, PRV and other interested parties.

As I said I was trying to recall from memory and I was also aided by some rather nice red wine which seemed to confuse my thinking so I got it back to front.

For some applications in connecting Garmin to other makers' units the Garmin Data -ve also doubles as the System -ve so the two have to be joined together then fed to the radio Data In -ve. The Garmin Data Out +ve goes to the radio Data In +ve.

This may not be correct for all systems but it worked for me connecting to Raymarine units. The requirement to join the two -ves together for some applications is not well explained in most manuals.

Apologies again for confusing every one.

 

[Ross D]

Thanks for the help on this one, I have checked all the wiring again, read both manuals extensively after a month of fiddling about I am still getting no-where. The only real thing I have managed to do is turn off the audible alarm on the radio that lets me know there is no GPS position.

The GPS is set to NMEA with a Baud rate of 4800, but the radio doesn't want to know. Any advice would be welcomed.

 

[elton]

Thanks for the help on this one, I have checked all the wiring again, read both manuals extensively after a month of fiddling about I am still getting no-where. The only real thing I have managed to do is turn off the audible alarm on the radio that lets me know there is no GPS position.

The GPS is set to NMEA with a Baud rate of 4800, but the radio doesn't want to know. Any advice would be welcomed.

Can you post a diagram of how you actually wired it? I have a similar setup (Garmin GPS45 to Navman 7100) and mine worked first time. I used the cable that came with the 7100 soldered to a bare end cable with the Garmin plug, and I used the same diagram as you. If you draw what you've actually done, your mistake will likely become apparent.

 

[Ross D]

Mine is wired up as per the diagram, the only difference being that the data out on the Garmin is the brown wire not the white, so my Garmin brown wire connects to the VHF yellow wire.

Ross

 

[elton]

Mine is wired up as per the diagram, the only difference being that the data out on the Garmin is the brown wire not the white, so my Garmin brown wire connects to the VHF yellow wire.

Ross

Assuming you have the GPS set up to output NMEA 4800 Baud, and the radio is configured correctly, the problem must be the cable. If you take care to accurately draw a diagram of your cable, and you use a multimeter to check that the wires are going to the right places, then you'll find the problem. It's extremely unlikely that you have a fault in the GPS or the radio that's causing this issue.

 

[ianat182]

Have been reading the replies to this thread , and have the handbooks here at the PC.
Apart from the baud rate to 4800 and the changes to the printed connections/colours there is one thing no-one has mentioned and that is the necessity to enter your MMSI number into the DSC VHF - before you can operate the DSC function.

This is a once only action apparently and applies to both theNAVMAN 7100 and 7200 models of radio.

hope this helps.

ianat182