Yes, it is possible. But it is necessary at first to assign this frequency input to one of the variables. For example parameter FR2=RP. (No need to use FR2 as frequency reference at all).
Then from the register (logical address 13306, can open 16#2067/9) it is possible to read the frequency of LI5 input.
Then from the register (logical address 13306, can open 16#2067/9) it is possible to read the frequency of LI5 input.