Help Needed interfacing Garmin to Dataline

Achilles

Member
Joined
10 Mar 2002
Messages
152
Location
Costa Blanca
Visit site
I have Dataline instruments installed on the boat, one of which is a Waypoint which essentially repeats information transmitted via NMEA from the GPS. Well I've just replaced the GPS because I had an old Phillips Mk8 which was constantly losing satellites and becoming a bit of a pain. I've replaced it with a Garmin 128 which grabs satellites quickly and hangs on to them like grim death. Problem is I can't seem to interface the Garmin with the Dataline instruments.
There are 2 inputs on the Dataline Databox labelled R Nav + and - (the old GPS was connected to these). Question is does the Garmin NMEA OUT go to the + and the NMEA IN to the -, or vice versa? I have tried connecting to both with no luck and gone through all the permutationsof NMEA/NMEA, NONE/NMEA etc. plus versions 1.5 and 2.0 and all the baud rates.
I have scoured the Dataline documentation for an answer but all it tells you is the sentences it accepts, which seem to be compatible with the Garmin.
Obviously I'm doing something very wrong but no idea what that is.

Any help very much appreciated.

Regards to all,

Kris

<hr width=100% size=1>
 

Oldhand

New member
Joined
21 Feb 2002
Messages
1,805
Location
UK, S.Coast
Visit site
Your Garmin should have at least 3 NMEA wires if it has NMEA IN and NMEA OUT. One wire must be NMEA IN +, one NMEA OUT + and either a single "common" (NMEA -) or an individaul NMEA - for both the IN nad OUT functions. You should connect the Garmin NMEA OUT + to the Databox RNav IN + and the Garmin "common" or NMEA - to the Rnav - terminal. What you have been trying to do is to create an IN/OUT loop!

The Garmin NMEA "common" could be the 12v -ve supply wire (bad practice), check your Garmin documentation.

<hr width=100% size=1>
 

Achilles

Member
Joined
10 Mar 2002
Messages
152
Location
Costa Blanca
Visit site
Thanks Oldhand,

I'm sitting here with the Garmin manual in front of me. There are 4 wires, a positive to the 12volt supply, a ground, NMEA IN and NMEA OUT.
I have connected the NMEA OUT to R NAV +, and NMEA IN to R NAV -, which I think is what you're saying. Maybe I should only have the NMEA OUT connected?



<hr width=100% size=1>
 

Oldhand

New member
Joined
21 Feb 2002
Messages
1,805
Location
UK, S.Coast
Visit site
NO, that is not what I am saying. The Garmin NMEA IN is for receiving external data into the GPS and would be connected to the Databox NMEA OUT + (normally to the Dataline instruments) if you wanted additional data available to be fed INTO the Garmin. With only the 4 wires you describe, Garmin must be using the 12volt -ve or "ground" as the NMEA common so the Databox RNav input requires:

Garmin NMEA OUT +ve to Databox RNav +
Garmin 12V -ve or "ground" to Databox RNav -, as well as to the 12v -ve supply.

If the Garmin and Databox are serviced from the same 12v source, i.e. the 12v -ve is common, then taking a connection from the Databox 12v -ve to the Databox RNav NMEA -ve would make the required NMEA -ve connection.

You need to differentiate between + and -, IN and OUT. An IN NMEA feed needs a + and - to make a circuit as does an OUT feed. IN and OUT may use the same -ve (common) but must use separate feeds or +ve's. The Garmin uses the same -ve or ground for both NMEA IN and NMEA OUT and for 12v -ve.

<hr width=100% size=1>
 

Achilles

Member
Joined
10 Mar 2002
Messages
152
Location
Costa Blanca
Visit site
Thanks again Oldhand,

Garmin NMEA OUT +ve to Databox RNav +
Garmin 12V -ve or "ground" to Databox RNav -, as well as to the 12v -ve supply.
As you suggest both Garmin and Databox are serviced from the same 12 volt supply.
I'll set it up as you suggest next weekend.

Many thanks for your help.

Best regards,

Kris

<hr width=100% size=1>
 

snowleopard

Active member
Joined
16 May 2001
Messages
33,645
Location
Oxford
Visit site
agreed, garmin gps are set to proprietory garmin output signals by default. it will need to be reset to nmea. you may have to experiment with which nmea version.

<hr width=100% size=1>
 
Top