code: private ModbusResponse getAndCheckResponse() throws ModbusException {
          ModbusResponse res = transaction.getResponse();
          if (res == null) {
              throw new ModbusException("No response");
          }
          return res;
      }
docs: Reads the response from the transaction
  If there is no response, then it throws an error
  
  @return Modbus response
  
  @throws ModbusException If response is null