Nav system hookup
 

On 17 Jan 2006 09:59:03 -0600, Dave wrote:

I'm setting up a simple navigation system consisting of my Garmin GPS and an
old laptop running SeaClearII. Presently my GPS is tied into the radio so
that if I have to press the red button the broadcast will include my
position. I'd like to maintain that arrangement.

When I hook into the laptop it will be via a plug-in connection on the GPS
led to the serial port. As a result there will be no exposed data in and
data out wires to lead to the radio. I suspect there's some easy way to
solve this problem, but don't know what it is off the top of my head. How
have others done it?

You will have to make a "Y" connection so that the GPS data out goes
to both the computer serial input and to the radio data input.

There are a couple of wiring diagrams on my GPS/NMEA site listed below
- look on the "Wiring Diagrams" page.


--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html
Newsgroup new user info: http://vancouver-webpages.com/nnq

Nav system hookup
 

Just use a small terminal strip...

Nav system hookup
 

OK- lets assume that your GPS is the "master"..for data supply to
peripherals..and your VHF/DSC and PC are recipients... Unless your
software in the PC has interrogative features, you really only need
data in...The VHF/DSC only requires data in for broadcast of position
on Ch. 70...Some equip. by other manufacturers will have Tx+ & Tx-
and Rx+ & Rx-, but garmin uses ground instead of data -...So from the
Garmin, you would take the blue wire(usully blue on garmin but may vary
dep. on model)and a wire from ground to the terminal board...this
becomes your data "main" buss..then connect the "data in" wires from
the VHF to that point Then you would also connect the leads from your
DB9 (either direct to the PC, or in the form of an extension cable) to
that point as well, blue(Tx+ from Garmin) to DB9 pin 2 and ground from
the buss, to pin 5...if your PC does interrogate for data, add a wire
from pin 3 to the strip, and connect the brown (data Rx+ from Garmin)
to the corresponding terminal going to pin 3... this gives two way
communication from the PC to GPS, for transferring waypoints, or if,
say your software supports an autopilot...This is assuming your PC will
accept NMEA data as is without a conversion. Here is a link with some
pin-outs and a wiring diagram to optimize data processing via RS232, as
well as some good general info:
http://www.google.com/url?sa=t&ct=re....au/rs232.html
&ei=3kHPQ6HQF6v6YImy7ekK&sig2=Qlt1b75MMEr8lHGg65v4 ig
(GMDSS is actually the equipment required under SOLAS, The DSC-capable
radio is one piece of the required equipment on
vessels requiring SOLAS compliance, as well as EPIRB, NAVTEX, Irridium
sat"C", etc)
Regards,
makv

Nav system hookup
 

I should clarify something...the Garmin colors I mentioned are for a
fixed mount GPS, if you are using a handheld, with a round 4 pin
connector, the data output wire is brown instead of blue (to pin 2) and
white instead brown (to pin 3).. Garmin usually has a color code tag
on the cable, but if not all their manuals are available in pdf form
on-line..

Nav system hookup
 

Flash update...now I get what you are saying, you have the molded PC
interface cable from Garmin...So yes,make an RS232 extension, pin 2
would be the data out positive to the terminal strip, pin 5 is ground
to the terminal strip and and pin 3 is the data in to the Garmin from
the PC.via the terminal strip. The radio will connect to pin 2 and 5,
then make up a new DB9 to the PC, wit the same connections, pins 2, 3,
and 9 from the PC to the corresponding terminals on the strip from the
Garmin DB9 pins 2,3, and 9....Took a while for that lightbulb to switch
on..phew..

Nav system hookup
 

Yeah Dave,
That's correct, but one thing to be careful of, RS232 cables are often
pinned differently from one end to the other,as you would have data out
from unit "A" to data in on unit"B" and visa-versa....in other words
pin three on the left end would show continuity to pin two on the right
end so you might have to "ring out" the cable with a VOM to make sure
your data is heading in the right direction..
markv

Nav system hookup
 

Yes, a basic extension, male to female, sould be pinned with all the
numbers alike end to end...
Markv

Nav system hookup
 

On 19 Jan 2006 16:52:03 -0600, Dave wrote:

Hmm. I'm thinkin' that maybe the easiest way to get what I need is to cut an
old external modem cable, or null modem cable, in half. Checking the web, it
looks like all of those cables use pins 2, 3 and 5, yes?

===============

Yes but if you use a null modem cable you need to know where the
crossover is.

Nav system hookup
 

Exactly...