There are 3 options to sync the two, but the first one is most recommended.

1) Sonar 3.0 as master, VS2480 as slave.
In Sonar 3, go to Options - Project - Sync and checkmark Transmit MTC and select the port to send it to (the MIDI output port connected to the VS2480). Then in the VS2480, go to Utility - Sync Parameters, and choose Sync Source as EXT.

* This will provide the smoothest operation and the best timing accuracy but will not sync tempo exactly.

2) VS2480 as the Midi TimeCode (MTC) master, Sonar3.0 as the slave.
In Sonar 3, go to Options - Project - Clock and choose SMPTE/MTC. In the VS2480 go to Utility - Sync Parameters and choose MIDI Out Sync Gen as MTC.

* This will provide good time accuracy but will not sync tempo exactly.

3) VS2480 as the Midi Clock master, Sonar3.0 as the slave.
In Sonar 3, go to Options - Project - Clock and choose MIDI Sync. In the VS2480 go to Utility - Sync Parameters and choose MIDI Out Sync Gen as Midi Clock.

* This will provide ease of syncing bars and beats and tempo between the two devices.