title: Iso 14443 request command
body: <p>I am trying to communicate with some smart card.
  I have reader which has method to Request 14443A type card.
  When I issue this command <em>sometimes it returns success, sometimes
  it fails</em>.
  Am I missing something in the <strong>14443A protocol maybe</strong>? Maybe the card enters some halt state? Or I must call halt state manually if there is failure? Or there is some other command I must call beforehand?
  Where can I get information on how to establish communication (on the protocol level) with ISO14443 card?
  Is there some tutorial for this?</p>
  
  <p>This is how code looks like(roughly):</p>
  
  <pre><code> SerialPort p = new SerialPort("COM1", 19200, Parity.None, 8, StopBits.One);
   p.Open();
  
   byte[] res;
   res = send(p, REQUEST_TYPEA_COMMAND);
   res = send(p, RESETA_COMMAND);
   // send some other command
   p.Close();
  </code></pre>
  
  <p>If I run above code for first time, all calls are OK. But after second run of the program, the first call (REQUEST_TYPEA_COMMAND) fails - until I restart the reader.</p>