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Michael Hannigan
Michael Hannigan, Engineer
Category: GPS
Satisfied Customers: 11826
Experience:  25+ Years Experience in Computers and Electronics. GPS Expert.
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Trying to connect my eTrex H using a USB-RS232 converter, but

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Trying to connect my eTrex H using a USB-RS232 converter, but I get the following error message: Plugin error: source: SPO_SERIALPORT.CPP, line: 284 My PC runs Windows 7 build 7601, the converter uses pl2303 prolific drivers

Hello. My name isXXXXX will be your primary care technician.

The SPO SERIALPORT.CPP error message is due to a communications error affecting the flow of data from the computer to the GPS. Typically, it is caused by the communications port of the computer.

To troubleshoot this issue try the following:

Update MapSource:

  1. Make sure that MapSource is not running
  2. Click the link:
  3. Click on Download
  4. Save the file to your Desktop
  5. Double-Click the file to Run (or Open) the update
  6. On the "Welcome to the MapSource Web Update" screen click Next
  7. Accept the terms of the license agreement and click Next
  8. When it is finished, click Done

Note: To check the version of MapSource currently running or to verify the update was complete in MapSource, click on the Help menu and choose "About MapSource..." This will display the version below the MapSource title.

Cable Connection: Check to ensure the GPS and the computer are securely connected

Serial Port Not Initialized: Make sure the Garmin GPS unit is plugged in and turned on and then restart the computer

Active Processes: Active processes that can use serial port on the computer can cause communication issues between the GPS and the computer. To determine if an active process on the computer may be causing a communication issue between the GPS device and the computer's serial port:

  1. Right-click on the clock at the bottom right corner of the screen and select Task Manager
  2. Click on the Processes tab
  3. Click on Image Name to alphabetize the list
  4. Look for any active process named Activesync, Hotsync, BBDVMonitor, Besmonitor, Intercept, LVCOMM, Tablet, UPS, WCESComm, WCESMgr, WeatherPak, x10net, ZUNE
  5. If any of the active processes listed in Step 4 are , right-click on it and select End Process
  6. Click Yes on the Task Manager Warning window to confirm the termination of the process

Note: The processes will start up again every time the computer is rebooted.


Bad Cable: Try another serial interface cable to ensure that the cable is not damaged and blocking some of the data transfer


Damaged Serial Port: As a last resort, try another computer to help narrow down the root cause of the problem between cable and communications port issues.

If detection is not achieved after trying these solutions, there may be a problem with the GPS device itself.


Please let me know if you have any questions.




Customer: replied 3 years ago.

Still get the same error message. Tried on another machine which gave the same message, then the following:

James, for some reason, the site isn't letting me see the enlarged image. Can you please upload to and then provide me the link here so I can download the error? Thanks.

Customer: replied 3 years ago.

The link is: Message.docx


Without results, it is difficult to evaluate satisfaction.

The rating is satisfaction with my level of service which is only part of what results in the final outcome. I do not have control over the quality of the product or the hardware itself. Please keep that in mind.

What I have given you is an exhaustive list of possibilities IF there is no faulty hardware. Determining a hardware fault is a possible final outcome that does not reflect poorly on my service.

In will review the error and get back to you.
Michael Hannigan and other GPS Specialists are ready to help you
Customer: replied 3 years ago.

Don't bother. Have used the serial port on one of my PCs rather than use the USB converter

That makes perfect sense. USB to serial adapters can be problematic. Since you were using the adapter, I was assuming that you were doing so because you didn't have a serial port available on your computer. You are much better off without the adapter if you don't need it. Was there a specific reason for using it initially?

Customer: replied 3 years ago.

Yes, my laptop, which I use for the majority of the time, has no serial ports.