use Data::Dumper;

my $txt = 'a,b,c,d,,,,,,';
my @fld = $txt =~ /([^,]*)(?:,|$)/g;

print Dumper \@fld;

__output__

$VAR1 = [
          'a',
          'b',
          'c',
          'd',
          '',
          '',
          '',
          '',
          '',
          ''
        ];