int TestUnitReady ( void ) {

// to be returned by this function
   int iRetCode; 

// instantiate the SRB appropriate for SC_EXEC_SCSI_CMD
   SRB_ExecSCSICmd srbExec;

// start filling it with all zeroes
   memset ( &srbExec, 0, sizeof ( SRB_ExecSCSICmd ) );

// ASPI command code
   srbExec . SRB_Cmd = SC_EXEC_SCSI_CMD;

// specify the host adapter number, as assigned by the ASPI manager
   srbExec . SRB_HaId = Adap_Id;

// SC_EXEC_SCSI_CMD is an asynchronous ASPI command, so the function
// returns immediately, and the event notify method is chosen to signal
// the command completion to the application program
   srbExec . SRB_Flags = SRB_EVENT_NOTIFY;

// SCSI2 device id of the target (LUN left to zero)
   srbExec . SRB_Target = myDevice_Id;

// SENSE_LEN is defined into WNASPI32.H
   srbExec . SRB_SenseLen = SENSE_LEN;

// CDB is the SCSI2 Command Descriptor Block (not to be confused with the
// SRB); 6 is the lenght of the SCSI2 command, TestUnitReady in this case
   srbExec . SRB_CDBLen = 6;

// this assigns the handle to the event notification object
   srbExec . SRB_PostProc = ( LPVOID ) hEventSRB;

// TestUnitReady is a 6 bytes long SCSI2 command, that have ben set to zero
// by the above memset; the first byte is the SCSI2 command code
   srbExec . CDBByte [ 0 ] = SCSI_TST_U_RDY;

// reset the event notification object
   ResetEvent ( hEventSRB );

// finally call the ASPI function
   pfnSendASPI32Command ( ( LPSRB ) &srbExec );

// if the command returns immediately with a SS_PENDING state it is
// time to wait for a single object
   if ( srbExec . SRB_Status == SS_PENDING )
      WaitForSingleObject ( hEventSRB, INFINITE );

// the event has been signalled: test the ASPI status byte
   if ( srbExec.SRB_Status == SS_COMP )
      iRetCode = 0; // OK

// check what happened (sense data automatically returned in the SenseArea)
   else
      {
        SenseKey = srbExec . SenseArea [ 2 ];
        SenseKey = SenseKey & 15;
        ASC      = srbExec . SenseArea [ 12 ];
        ASCQ     = srbExec . SenseArea [ 13 ];
        AddToLogFile ( "TestUnitReady       ", SenseKey, ASC, ASCQ );
        switch ( SenseKey )
           {
             case 0x01:
                  iRetCode = 0; // not a good practice, but OK...
                  break;
             case 0x06:
               // Power On reset or Bus Device reset
                  if ( ASC == 0x29 && ASCQ == 0x00 ) { iRetCode = 1; break; }
             default:
                  DisplayStatus ( "TestUnitReady", srbExec . SRB_Status,
                                  srbExec . SRB_HaStat, srbExec . SRB_TargStat );
                  iRetCode = 99;
           }
      }

   return iRetCode;
}