Get a Roland DIF-AT interface. You can not use ADAT with the VS-2480 without one, because the VS-2480 does not output audio data that an ADAT unit can interpret without a conversion interface.
Turn off the VS-2480 before making any connections. This is a standard safety precaution when wiring between different audio components.
Connect one end of an ADAT-compatible optical cable to the "optical in/out" connection port on your ADAT unit. The label for this port will vary slightly between models. Consult your ADAT unit's documentation for the correct connection port. Connect the other end of the optical cable to the ports labelled "OUT/IN" under "ADAT" on the back of the DIF-AT.
Connect one end of the ADAT unit's sync cable to the sync port on your ADAT unit. Connect the other end to the port labelled "SYNC" under "ADAT" on the back of the DIF-AT. This connection will synchronize the ADAT unit's record functions with the VS-2480.
Connect one end of the RMDB2 cable to the connection port labelled "R-BUS 1" on the back panel of the VS-2480. Connect the other end of the RMDB2 cable to the connection port labelled "RMDB2" on the back of the DIF-AT.
Turn on the ADAT unit and then turn on the VS-2480. The DIF-AT is powered by the VS-2480 and does not require a separate power cable or on/off switch.
Select "Utility" on the VS-2480's interface screen. Press the "Page" button until the page labelled "R-BUS" appears. Press "F2" to bring up the "R-BUS CONFIG" screen. Press "F," and the DIF-AT's settings screen will appear. Change the "INPUT SELECT" option to "ADAT." You are now ready to use ADAT recording with the VS-2480.