Could you please elaborate more?
What do you mean not using the memory storage card?
Are you talking about the removable flash card on the cFP-2020? Are you talking about the regular flash card on the FP-20xx?
If you need to store (log) data, you will require a place to put it (flash card) in the FP-20xx...Remember that the flash card of the FP-20xx is recognized as a C Drive. All you need to do is to use the File I/O VIs to log the data to this drive.
If you want to have data in RAM, you could create arrays, or even RT FIFOS, but this is volatile data.
One last idea...you could check in the market to see if there is a kind of non-volatile data logger device that you can connect to the serial port of the FP-20xx.