code: final public int[] readInputRegisters(int serverAddress, int startAddress, int quantity) throws
              ModbusProtocolException, ModbusNumberException, ModbusIOException {
          ModbusRequest request = ModbusRequestBuilder.getInstance().buildReadInputRegisters(serverAddress, startAddress, quantity);
          ReadHoldingRegistersResponse response = (ReadInputRegistersResponse) processRequest(request);
          return response.getRegisters();
      }
docs: This function code is used to read from 1 to 125 contiguous input registers in a remote
  device. The Request PDU specifies the starting register address and the number of registers.
  In the PDU Registers are addressed starting at zero. Therefore input registers numbered 1-16
  are addressed as 0-15.
  
  @param serverAddress a slave address
  @param startAddress  starting register address
  @param quantity      the number of registers
  @return the register data
  @throws ModbusProtocolException if modbus-exception is received
  @throws ModbusNumberException   if response is invalid
  @throws ModbusIOException       if remote slave is unavailable