I finally got it to work with the code structure

use IO::Socket;
use IO::Select;

$sock = new IO::Socket::INET (
                                PeerAddr => $$display{'dp_ipaddress'},
                                PeerPort => $$display{'dp_tcpport'},
                                Proto    => 'tcp',
                                Blocking => 0,
                                Timeout  => 10,
                               );
  my $sel = IO::Select->new($sock) or die "IO::Select error $!";
  if ($sel->can_write(10)) {
    $sock->autoflush(1);
.             
      $msg = $msg . CheckSum($msg);
      $sock->send($msg);
      my $resp;
      if ($sel->can_read(10)) {
        $sock->recv($resp, 1024);
      }
  } else {
    print "Error: $@: $!\n";
  }
.
.
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