title: WFS_ERR_SIU_INVALID_PORT (-801) error when enabling events for SIU
body: <p>I am trying to enable events for SIU device like this:</p>
  
  <pre><code>    LPWFSRESULT lpWfsResult;
      WFSSIUENABLE commandData;
      commandData.fwSensors[WFS_SIU_OPERATORSWITCH] = WFS_SIU_ENABLE_EVENT;
      commandData.fwIndicators[WFS_SIU_OPENCLOSE] = WFS_SIU_ENABLE_EVENT;
  
      HRESULT hResult = WFSExecute(hService, WFS_CMD_SIU_ENABLE_EVENTS, &amp;commandData, 10000, &amp;lpWfsResult);
      cout &lt;&lt; "Events enabled?:" &lt;&lt; hResult &lt;&lt; endl;
      WFSFreeResult(lpWfsResult);
  
  </code></pre>
  
  <p>This works as expected (hResult = 0) in one of the test ATMs.
  However on another test ATM, this returns WFS_ERR_SIU_INVALID_PORT (-801).</p>
  
  <p>As per the <a href="ftp://ftp.cenorm.be/CWA/CEN/WS-XFS/CWA16926/CWA%2016926-10.pdf" rel="nofollow noreferrer">XFS doc</a>, this means:</p>
  
  <blockquote>
    <p>An attempt to set a port to a new value was invalid because the port does not exist or the port is pre-configured as an input port.</p>
  </blockquote>
  
  <p>I don't really understand the document's description. Can someone explain why this status is returned and what should be done?</p>
  
  <p>Thank you.</p>