Need Help Building PC-GPS Cable For Downloading

On Wed, 25 Jan 2006 23:35:03 GMT, DJ <freebird25103 DeleteThis @yahoo.com> wrote:

>Tyring to avoid the cost of buying a ready made cord. Any ideas out there
>as to the various ways to construct a cable to download from the computer
>to the GPS. Understand you need a serial DB9 female plug, a 12 volt power
>source (I don't know amperage ) and of course the loose wires from the GPS
>. I have a Garmin 178C and I do know which color wire go where....what I
>need is some creativity or hardware ideas as to how to get them all
>together and then still be able to take my GPS and its cable and put itr
>back on the boat,,,Anybody ever done anything like this before??????or am I
>being penny wise and pound foolish for even trying?

There are a couple of wiring diagrams on my GPS site that may be
useful - as well as my NMEA FAQ.

The manual for your GPS should show which wire is data in, and which
is data out - connect the GPS data in to the PC data out, and vice
versa, and connect all the grounds together.

You shouldn't need a 12 volt supply if the GPS has internal batteries.

If your computer does not have an "old fashioned" RS-232 serial port
(usually a DE-9 male connector), then you will need to buy an RS-232
<-> USB cable (which really has some electronics embedded in the DE9
connector)

>
>I have the Blue Chart software on my computer.....but no data card or card
>reasder (another expensive USB cable).....Thanks much...DJ

When transferring BlueCharts, the GPS will have to be set to
"Garmin/Garmin" protocol - somewhere under "System/Communications" or
similar.

--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca
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DJ wrote:
> Tyring to avoid the cost of buying a ready made cord. Any ideas out
> there as to the various ways to construct a cable to download from
> the computer to the GPS. Understand you need a serial DB9 female
> plug, a 12 volt power source (I don't know amperage ) and of course
> the loose wires from the GPS . I have a Garmin 178C and I do know
> which color wire go where....what I need is some creativity or
> hardware ideas as to how to get them all together and then still be
> able to take my GPS and its cable and put itr back on the
> boat,,,Anybody ever done anything like this before??????or am I being
> penny wise and pound foolish for even trying?
>
The color codes for the various Garmin plugs are available from the Garmin
website. Invariably the blue lead from your multi-point plug on the 178C is
data out, and connects to pin 2 on the DB-9 plug. The brown lead is data-in,
and connects to Pin 3 on the DB-9, and the black lead is ground, and
connects to pin 5 on the DB-9. If you look at the DB-9 thru a magnifying
glass you will be able to see the pin numbers on the plastic moulding. You
only use the top row (5 pins)

You pick up the wires from the cable supplied with your 178C, which will
also have power leads. At the opposite end to the actual plug, the wires
terminate in a bundle of loose leads, some of which will be tied back if the
unit is already installed. If the unit is not yet installed, you will need
to pick up the positive supply with the red lead, and the negative with the
black lead. The DB-9 plug does not supply power to the unit, so all you need
connected to this plug are the blue, brown and black leads, the latter being
also connected to battery negative.

The 178C may well have other colored leads dependant on whther there are
alarms etc. set up. these can be ascertained from the website wiring
diagrams.

If you have lost the cable/plug to the Garmin, forget it, and buy a new
cable.

DB-9 self assembly plugs are available from most radio/computer shops. You
need to be reasonably competent with a soldering iron.

To take the GPS home, disconnect the plug at the back and leave the cable on
the boat!

Dennis.
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