That means write() returned undef, which means the write failed entirely. Try checking if $^E contains a useful error message: my $count_out = $PortObj->write($sendData) or die "write failed: $^E";

Try $PortObj->error_msg(1); $PortObj->user_msg(1); right after new() as shown in the module's docs.

Make sure that your handshake really is none, that depends on how the other side of the serial connection is configured.

In reply to Re^3: Virtual COM port write by Anonymous Monk
in thread Virtual COM port write by jismake

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