protected void FlushWrite(bool sendEND = true)
 {
     if (DriverIsReady)
     {
         try {
             _driver.FlushWrite(sendEND);
         }
         catch (Exception ex) {
             Close();
             throw ex;
         }
     }
     else
     {
         throw new System.InvalidOperationException("Cannot execute FlushWrite(...). Driver not initialized or is closed.");
     }
 }