The format of the response is potentially difficult so some sort of parser would probably be the safest option. The possibility of commas in the quoted parts of the response makes splitting on comma unreliable. Assuming fields are delimited by commas and sub-fields are one inside the double-quotes and one after them, this should work.

use strict;
use warnings;

use Data::Dumper;

my $rxFlds = qr
   {(?x)
       "
       ([^"]*)
       "
       ([^,]*)
       (?:,|\z)
   };

my $resp =
   q{"F059"3,"Invalid blech"99,"","This, that"33,""77,};

my @flds;
while ( $resp =~ m{$rxFlds}g )
{
    push @flds, [$1, $2];
}

print Data::Dumper->Dumpxs([\@flds], [qw{*flds}])
[download]

Here's the output

@flds = (
          [
            'F059',
            '3'
          ],
          [
            'Invalid blech',
            '99'
          ],
          [
            '',
            ''
          ],
          [
            'This, that',
            '33'
          ],
          [
            '',
            '77'
          ]
        );
[download]

I hope this is of use.

Cheers,

JohnGG