Connecting MGS1600 to Arduino Mega

Hi,
I am trying to connect MGS1600 sensor to arduino Mega. I have motors connected to arduino and I would like to read the sensor's data and control the motors accordingly.

What connections do I need to make and what settings do I need to change in arduino? I have powered the sensor independantly through a 9V battery connected between pins 5 & 14 on ARDUINO's RS232 connector.

Thanks.