code: final public int[] readFifoQueue(int serverAddress, int fifoPointerAddress) throws
              ModbusProtocolException, ModbusNumberException, ModbusIOException {
          ModbusRequest request = ModbusRequestBuilder.getInstance().buildReadFifoQueue(serverAddress, fifoPointerAddress);
          ReadFifoQueueResponse response = (ReadFifoQueueResponse) processRequest(request);
          return response.getFifoValueRegister();
      }
docs: This function code allows to read the contents of a First-In-First-Out (FIFO) queue of register
  in a remote device. The function returns the queued data.
  Up to 31 queue data registers can be read.
  The function reads the queue contents, but does not clear them.
  If the queue count exceeds 31, an exception response is returned with an error code of 03
  (Illegal Data Value).
  
  @param serverAddress      a slave address
  @param fifoPointerAddress address of a fifo pointer register
  @return the data register value
  @throws ModbusProtocolException if modbus-exception is received
  @throws ModbusNumberException   if response is invalid
  @throws ModbusIOException       if remote slave is unavailable