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Connecting Your GPS to Your Computer

How to set up the correct connection between your mapping software and your PC


Posted: 9 August 2008

Garmin header
Whatever mapping software you use you will need to ensure that your connection is set up properly. These notes apply to all software.

Step 1
Buy the correct cable(s) and drivers (if necessary) then correctly install/ link them together.

Cables come either as part of the GPS package or have to be bought as an accessory. In either case you have to ensure that you have the correct connection for your PC. The computer end of the cable is either a standard serial (RS232) female D shaped connector or, with the latest generation of GPS, a USB connection.

Many modern PCs and laptops do not have RS232 interfaces as they rely on the faster USB system. Users with the D shaped connector must buy an extra cable to connect to the original RS232 to convert it to a USB connector end to be able to plug it into their computer. This is called an USB to RS232 converter cable.

Be very careful if you buy a non-branded product, as it may not work correctly. Always buy from a reputable source like your Garmin dealer. Whatever USB cable you use, whether a converter cable or a standard USB cable, you will need to install the driver software that came with cable to make it work.

Step 2
Ensure you create the correct data pathway between GPS and PC to enable them to talk to each other.

a) GPS Connection Setup
On leaving the factory your GPS will be set to the correct default setting - GARMIN. Normally you will not need to change this.

(b) Computer Connection Setup
i. Serial Port Connection
If you connect your GPS directly to a serial port, you will need to set your digital mapping system to COM1 in GPS Setup.

ii. Connection via a USB to RS232 Converter Cable
If you connect to a USB port with a USB to RS232 converter cable, the COM setting could be any number between from 2 upwards depending on the other equipment you have connected. Although you can find the correct port number by trial and error, you may find the following approach easier:

First of all plug your cable into the computer and switch on the GPS receiver.

Go into the 'Control Panel'. Depending on the version of Windows you have, this is usually found from the Start menu.

If you cannot find it, go into the Help system and find out where to locate it.

Click on System, then Hardware, then Device Manager, then 'Ports (COM and LPT1)’.

Now click on the '+' symbol to reveal the different types of ports you have.

Look for the 'Serial on USB Port' or 'USB Port' or something similar. This will show which COM port is currently being used - for example (COM4).

Now close down the various windows you have opened and get back to your digital mapping system.

Enter the COM port number into your digital mapping system that your computer is using for the USB connection.

iii. Connection via a USB Cable
All you need to do here is connect up your GPS to the PC via any one of the USB ports and set your digital mapping system to 'USB'. You should hear a two-tone sound when the GPS is connected. If a single tone sounds or there is no tone, check that you have loaded the USB driver correctly. If in doubt, reinstall.


Garmin GPS GPS Training Tip
If you have RS232/USB connection problems in the future, check through connection routine as the COM Port number being used by your mapping system may have changed.

Garmin GPS GPS Training Tip - Before you buy!
Like any software you purchase, once you have opened the package it's yours. No one will contemplate refunds on software just because it doesn't work with your GPS or PC or is the wrong map scale. Remember that not all mapping software is compatible with all models of GPS and vice versa, so do your homework before you buy. In the long run it could save you time, effort and money. Check that your computer is the right specification to run the software. You will need a DVD drive and a connection to the Internet.

About the contributors

Dave Mycroft Dave Mycroft is OM’s very own routes editor and a self-confessed GPS nerd. He’s an outdoors and technology writer with impressive navigation credentials earned on some proper hills and trails.
Garmin Garmin is a world leader in GPS and has an excellent range of products suited to British hill walkers. Not only that, we love the way it's approachable and supportive of projects like this one or Geocaching. How refreshing!
GPS Training GPS Training is the acknowledged leader in GPS training and advice. This small, family-run company runs accessible training courses and will give you the best possible advice on kit. You won’t go wrong talking to these guys before you buy – they know their stuff and will tell you the truth.

GPS Basics
Getting Started
GPS Buyer's Guide
Using Your GPS
GPS and Your PC

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Discuss this story

Dave I recently bought a USB-RS232 Coverter Cable to use on my laptop and while doing some research before purchase came across this article.

Today when I received the cable I was having difficulty connecting it to the COM Port so recalling and referring to your article I had no problems connecting it up as per your instructions.

Well explained article. Thanks for that.


Posted: 30/03/2009 at 22:44

Thanks Lindsay, it's always great to know the guide is coming in useful

Posted: 30/03/2009 at 23:05

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