RobotStudio event

communication with BarrettHand through the RS232 serial port

Hello, i have to make an application of communication between the robot controller IRB120 and the BarrettHand through RS232 serial port. 
I Have the necessary information and libraries of BarrettHand but i don´t know to do the programming in Rapid. 
Can anyone help or know where i can get some manual for this item?
Thank You.