Hello! The LI-6800 can actually create an Excel file automatically. Go to the Log Files tab, Logging Options, and select “Also Log Data to Excel File”. This is a nice feature because it has the equations built-in, so if you need to change a parameter like leaf area, everything that depends on leaf area also changes.
LI-COR doesn’t have an R program written to specifically open LI-6800 files, but it should be fairly straightforward. You would want to open the text file (non-Excel file). You can write the program to capture the columns after the [Data] tag.