BrowserUK, You idea solved the problem. I was able to check the status of the com port before and after running different programs and using the copy to port mechanism.

What I found was that I was using xoff for handshaking and when I changed that to none the additional characters come through Win32::SerialPort. Looks like xoff handshaking handles certain bytes differently.

Thanks for the guidance. I have added the information you provided to my toolbox. So Win32::SerialPort was working correctly, I just had wrong parameters.

Mike