if ($handle == $mcserver) {
  if (sysread $handle, $result, 1024) {
    # ... deal with it ...
  }
  # if the program gets here, the controller went away.
  else {
    logger("Motion controller died unexpectedly.");
    $mcserver->shutdown("SHUT_RDWR");
    $links->remove($mcserver);
    $mcserver = new IO::Socket::INET(PeerAddr => $mchost, PeerPort => $mcport, Timeout => 6);
    $links->add($mcserver);
  }