D:\Strawberry\c\bin\gmake.exe test -- NOT OK
//hint// to see the cpan-testers results for installing this module, try:
reports BBIRTH/Win32-SerialPort-0.22.tar.gz
Stopping: 'install' failed for 'Win32::SerialPort'.

 

.. just confirming that with the 32-bit version of Strawberry Perl without USE_64_BIT_INT portable version the Win32:SerialPort works fine.

One issue :  the installer fails if you don't have a COM1 port on your system, but you can override this with

perl Makefile.PL TESTPORT=COMx when building the Win32::SerialPort module.

 

It's a 32-bit build of perl, but it does have 64-bit integers. (Advice provided earlier in this thread that such a perl is unavailable is wrong.)

I suspect that it's perl's 64-bit integers that are creating your problem.
If you go to http://strawberryperl.com/releases.html you'll see there's a without USE_64_BIT_INT portable edition that you can install anywhere you like.
It will give you 32-bit integers - which will hopefully allow Win32::SerialPort to perform correctly, thereby proving that there's a bug in the 64-bit handling of Win32::SerialPort (which should be reported).

Working Version with WIN::Serial32