Simple application for testing COM ports for GPS connectivity.
Starting with Windows Vista, Microsoft has elected not to include the "HyperTerminal" accessory. Unfortunately, this is a useful tool for diagnosing difficulties with GPS connections, etc., as it features the ability to "view" the information coming from the GPS into the computer, unencumbered by other applications.
We have provided an alternative, MTTTY which is attached to the bottom of this page.
To use MTTTY:
1. Follow the How To Install instructions, below, to download MTTTY to your Windows Desktop.
2. In the upper right hand corner, the Port drop down list contains a list of the COM Ports (real or virtual) found on your PC. Select the Port that the GPS is connected to. (If you're not sure, pick the first port listed, then repeat the test until the GPS is found.)
3. Next to Port, Baud is listed. Most GPS units transmit at 4800 Baud. Thus, select 4800 from the Baud list, unless you are using a different Baud rate on your GPS.
4. Leave all other settings at their default and choose Connect from the File menu.
At this point, one of three things can happen:
I get an error message.
This means that the COM port you have selected is not available or functioning properly. Repeat the process, trying a different COM port. If none of these reveal GPS input, then the problem lies in the physical serial port, the USB-to-Serial adapter cable (if used) the GPS receiver, or the connection between the two. If you are certain that you are selecting the proper COM port, contact your computer (or USB-to-Serial adapter) manufacturer for further troubleshooting tips.
I get a blank screen.
This indicates that the COM port you've chosen is not currently receiving NMEA data. Choose Disconnect from the File menu and repeat the process, trying a different COM port. (Repeat the above steps for other COMs, replacing COM1 with whatever COM ports are available on your PC.) If none of these reveal GPS input, then the problem lies in the physical serial port, the USB-to-Serial adapter cable (if used) the GPS receiver, or the connection between the two. If you are certain that you are selecting the proper COM port, contact your computer (or USB-to-Serial adapter) manufacturer for further troubleshooting tips.
I get a screen with text scrolling upward.
You're successfully connected to your GPS unit! Good GPS data will resemble the following:
The data you see scrolling by indicates your current position (among other things). Note the COM port used and exit MTTTY. When asked if you want to disconnect now, click on Yes. When asked if you want to save session "Test", click on No.
5. When finished viewing the screen, select "Exit" from the File menu. When asked if you want to disconnect, click on Yes.
How To Install
Click the link below. In most instances, your web browser will ask if the file should be Opened, or Saved to your computer. Choose Save, then select a location to Save the downloaded file In. If you are unfamiliar with downloading software, we recommend choosing your "Desktop"; select Save In, Desktop and press Save. Once the download completes, double-click the MTTTY application that appears on your Desktop to start it.