SAP EWM issue with RF transaction

Hello,

I am trying to create a RF transaction which takes ODO (Outbound Delivery Order ) number as input in my first screen  and displays material no, item and quanity for that ODO number  in the second screen , can any one please tell me how to get the ODO number given at the screen to our function module , This is not like MPP we should use some methods to get the ODO number in the PAI fm of first screen.  Please suggest.

Thanks,

RG