in reply to Win32::SerialPort is not blocking

You've disabled handshaking, and applied timeouts to your reads: 

$PortObj->handshake("none");
...
$PortObj->read_interval(100);    # max time between read char (millise
+conds)
$PortObj->read_char_time(5);     # avg time between read char
$PortObj->read_const_time(100);  # total = (avg * bytes) + const

[download]

It is doing what you've asked it to do.

Try adding handshaking; or extending your timeout; or add your own line buffering loop.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In Section Seekers of Perl Wisdom