lookup for values from XI to R3

Hi Experts,

i need to get values from r/3 table whenever i pass two values from XI.

Can I write a function module(RFC), which imports these values from XI and exports the values needed by XI from R/3 custom table.(infarct I'm going to of RFC lookup)

Is there any other way to get values from R/3 custom table.

let me know your thoughts.