Your initial premise that you could read binary data from the DATA file handle is wrong.

Works for me.

use feature qw( say );

binmode DATA if $ARGV[0];
while (<DATA>) {
   say sprintf "%v02X", $_;
}

__DATA__
abc
def
[download]

>perl a.pl 0
61.62.63.0A
64.65.66.0A

>perl a.pl 1
61.62.63.0D.0A
64.65.66.0D.0A
[download]