in reply to Re^3: Win32::SerialPort, buffer overflow
in thread Win32::SerialPort, buffer overflow

when debugging, I prefer to see my values in quotes (or other markers), and possible control characters (or "extended" characters) "translated". Therefore I'd suggest instead of simply printing the values, perusing Data::Dumper (core module), or Data::Dump or somesuch.
Although it probably isn't a case of homoglyphs, perhaps the different representation by Data::Dumper might help you spot something.