Another approach:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my @strings = map pack('H*', $_), '30abff', 'ab30ff', '30', 'ab1a30';
 dd \@strings;
 ;;
 for my $bs (@strings) {
   printf 'here: ';
   my @bits = unpack '(B8)*', $bs;
   print join '//', @bits;
   }
"
["0\xAB\xFF", "\xAB0\xFF", 0, "\xAB\x1A0"]

here: 00110000//10101011//11111111
here: 10101011//00110000//11111111
here: 00110000
here: 10101011//00011010//00110000
[download]

Please see pack, unpack, perlpacktut.

Update: Added another example string:  '30abff'