Grandfather, I think you are right there seems to be some kind of filtering or processing that does not pass through certain types of bytes. I have included the following two settings in my code to show errors.

$port-> error_msg(1);          # prints hardware messages like "Framin
+g Error"
$port-> user_msg(1);          # prints function messages like "Waiting
+ for
[download]

I was able to generate buffer overflows in a test I ran to prove the overflows and framing errors would be caught, but that does not account for the missing characters in my code. Since running the code does not generate buffer overflow errors at this time. Buffer overflows would account for missing characters at the end of the stream.

The file from the scanner is 67452 bytes and the program here downloads 62451 bytes. I was running a port monitor and watch the 01, 00, 02 and 03 come from the scanner on the download but they did not seem to get passed through Win32::SerialPort as characters. The program I am mimicing does include all those characters in the output file.

Thanks Mike