We have examined many different USB adapters and found the type that we sell to work best with all of our instruments. Other adapters may work, but they may not.
We can only guarantee the FTDI adapter that we sell. It is included with many of the LI-COR instruments that require serial communication with a computer. We have found that some third-party USB adapters (Prolific, for example) do not accurately transmit all the data from the instrument to the computer, or vice versa. You should use an adapter with an FTDI chipset, and Belkin and Keyspan adapters typically work well with our instruments too.