This module hasn't been updated since 1999. That's a serious issue.
The interface is messy and one needs to study the examples, but supposedly it's the same as Device::SerialPort.
A problem is that I need to write klugy code in a BEGIN block to test if I'm in Windows and use the Windows::SerialPort module instead of Device::SerialPort. Somebody should look to merging the two modules.
[Ok... I've since realized that Device::SerialPort is a mimic of the Win32 module, but still, there should be ONE module.]