I used the r305 sensor with the rs232 board and connected to the arduino mega 2560 board to pins 2 and 3 respectively as stated in the adafruit code present in the official software, please help me resolve this problem
You know that you can copy the text of the serial monitor and paste it here? I assume you did not know.
You should also post your code.
And please read one of the atickies how to post your code using code tags.
as stated in the adafruit code present in the official software
AdaFruit is not responsible for any of "the official software" for the Arduino.
So, you need to post links to the hardware and the libraries that you use.