Not being a regex expert, I've come up with this:

my $string = '---LL--C----LCSH-------CSHL-------LCSLH-------LCCHLSHCL-
+---';
while ($string =~ /([CHS][LCHS]+[CHS])/xg) {
  print "$1\n";
}
__END__
CSH
CSH
CSLH
CCHLSHC
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