[C320-list] Data IN ... Data OUT Garmin to AutoHelmST4000Plus

[Bill Culbertson]

Jeff is correct, Bruce.  What you are calling the 12v Ground is indeed the 12v Ground and it is also the data ground. The data signal voltage on the brown wire is relative to the Garmin ground wire.  So without that wire connected to the -ve end of the NMEA input of the autopilot, the Garmin signal voltage connected to the +ve end of the NMEA has no reference point.

What can be confusing about the wiring is that the Garmin both sends data  and receives data.  So logically the garmin would have six wires.  data out and its gnd, data in and its gnd, 12v and its gnd.  As is customary when there is not an electrical reason to keep separate, the Garmin unit uses the single gnd wire for all three gnd purposes.

Garmin     data -> -> -> -> data -> (brown)  -> NMEA + in
                data <- <- <- <- data <- (white)
                12V
                GND    -    -    -    -    -    -    -    -    NMEA - in

Remember Jeff's advice to switch the Garmin unit to NMEA mode from Garmin mode.  I forget this nearly every time I bring my 176 back onboard from having taken it home to transfer track data to my PC. The PC wants Garmin mode, the ST4000 wants NMEA mode.  I've taken to leaving it in NMEA mode.  It's less disturbing if my PC won't upload track data then when I'm onboard and the Garmin won't talk to the ST4000.

 -bill

----- Original Message ----
From: Bruce Stanley <brucestanley36 at gmail.com>
To: C320-List <c320-list at catalina320.com>
Sent: Sunday, December 23, 2007 4:28:47 PM
Subject: Re: [C320-list] Data IN ... Data OUT Garmin to AutoHelmST4000Plus

Hi Jeff
Do I read the 2 lines below:
----------------------------------------------------------
Brown Data OUT wire from Garmin  --->  To Raymarine NMEA +
*GROUND wire* from Garmin cable    --->  To Raymarine NMEA -.
----------------------------------------------------------
to mean that the *"12v" GROUND wire* from the Garmin ---> to Raymarine
NMEA???????

Bruce Stanley
Sydney
==================================================
On Dec 24, 2007 6:54 AM, Jeff Hare <catalina at thehares.com> wrote:
> Hi Bruce,
>
>  I probably should have researched this first, but from memory and what
> you've provided:
>
>  Garmin uses a 4 wire cable.  Power +12, NMEA Data IN,  NMEA Data OUT,
> GROUND (0v)
>
> For this application, I believe you'll be using the GARMIN BROWN (Data
Out),
> and the Ground wire.
> On the Raymarine end, I believe you'll connect:
>
> Brown Data OUT wire from Garmin  --->  To Raymarine NMEA +
> GROUND wire from Garmin cable    --->  To Raymarine NMEA -.
>
> This effectively TRANSMITS NMEA Sentences From the Garmin to the ray
marine
> NMEA Listening port.
>
> Since you don't need your GPS LISTENING to NMEA 1083 sentences from the
> RayMarine autopilot (other sources), you won't use the White DATA IN line.
>
> Does this make sense?
>
> Also, when you set up your Autopilot, you need to be sure that it's
> listening to NMEA 1083 as well as setting the Garmin transmitting mode to
> NMEA 1083.
> Usually the Garmin transmits using "GARMIN" protocol, so if you haven't
> changed that, you'll need to.
>
> I hope I got this right, but no harm will come if polarity is reversed
here,
> because they're only signal lines.
>
> If you need longer runs, standard network cable CAT-5 used for computer
> networks is just fine for this.
>
> -Jeff
>
> PS: I believe that you can drive up to 3 NMEA devices from the NMEA 1083
> output of your Garmin.
>
> -----Original Message-----
> From: c320-list-bounces at catalina320.com
> [mailto:c320-list-bounces at catalina320.com] On Behalf Of Bruce Stanley
> Sent: Sunday, December 23, 2007 3:54 AM
> To: C320-List
> Subject: [C320-list] Data IN ... Data OUT Garmin to AutoHelmST4000Plus
>
>
> Data IN and Data OUT
> Can you clarify?
>
> Firstly, I have the GarminGPS48 connected to my ST4000+
> I have 12v power, but
> "NO DATA".
>
> Garmin say:
> White=Data IN
> Brown=Data OUT
>
> ST4000Plus say:
> NMEA +, and
> NMEA -.
> ==============================================
> do I connect Garmin "White" to ST4000Plus "NMEA -"        ?????????????
> ==============================================
> HELP, PLEASE
> Have a great Festive Season, tooooooooooo
>
> Bruce Stanley
> C320 #1084
> Sydney Australia
>
> PS I have looked on Garmin and Raymarine sites...2 glasses of Red Wine
> Later I gave up!
>
>
>
>


      ____________________________________________________________________________________
Be a better friend, newshound, and 
know-it-all with Yahoo! Mobile.  Try it now.  http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ