Each opendevice() must eventually be matched by a call to closedevice().
All I/O requests must be complete before calling closedevice().  if any
requests are still pending, abort them with abortio().

    if (!(CheckIO(SCSIIO)))
        {
        AbortIO(SCSIIO);   /* Ask device to abort any pending requests */
        WaitIO(SCSIIO);    /* Wait for abort, then clean up */
        }
    CloseDevice(SCSIIO);   /* Close SCSI device */