Originally Posted by Motley
1 How do I know that my computer has "recognized" my garmin?
2 What is a "com device"?
3 I have no other programs that might interface with gps
4 What are the correct settings in Opencpn?
5 How do I know what my garmin is talking, it doesn't say anything to me...?
1. When you connect your Garmin GPS to your USB port you can open Device Manager (using Control Panel). Find "Ports (COM & LPT)" on the list. Click the "+" sign to the left of that item to see the entries for that category. If the computer has recognized your GPS you should see it listed.
2. A "COM device" is a communications
device. It refers to anything which is connected to the computer via a serial port. Serial ports
were called "com" or communications ports
because in the early days the most common devices connected to them were modems, used to allow computers
to communicate with one another over telephone lines.
3. You're probably right, but if you find your GPS listed under Ports in Device Manager but you still can't get OpenCPN to communicate with it revisiting this issue might be advised.
4. Open the toolbox in OpenCPN. Select the "GPS" tab. The NMEA Data Source field should list the com port which was associated with your GPS in the Device Manager Ports list. If not, click the little triangle at the end of the field to see the list of ports OpenCPN knows about and choose the one associated with your GPS. Com ports are identified by number, so if your GPS shows up in Device Manager associated with COM7 you'll want to choose COM7 from the list in OpenCPN. The NMEA Baud Rate field should be set to 4800. For diagnosing problems, check the "Show GPS/NMEA data stream window".
5. Most Garmin GPS receivers
allow you to set interface options. Choose NMEA rather than GRMN. That will cause the GPS to send NMEA sentences to OpenCPN rather than using the proprietary GRMN format which OpenCPN can't process. If you checked the "Show GPS/NMEA data stream window" you'll be able to see the text coming from your GPS in a little window that OpenCPN puts on the screen
. As you watch that data stream you'll probably recognize a few items as latitude, longitude, course over ground, speed over ground, and so forth. Usually all you're looking for it evidence that readable data is flowing from the GPS to the program.