External serial communications

I am writing a program that draws a robot based on values sent from a vex cortex I had trouble getting the serial port to send data to my program I was wonderng if I have to request for the serial transmission to start by sending a value to the cortex from my program?
I can see the vaules in the robot c debug window though.

You do manually control when data is sent and received over the serial port. This page has some documentation on using the serial link: http://www.robotc.net/wiki/VEX2_Functions_Serial_Link