DALI (Digital Addressable Lighting Interface) is an international standard for controlling certain LED and fluorescent ballasts and other load devices. DALI ballasts are assigned an address by which they receive control commands. Up to 64 ballasts may be controlled on a DALI signal bus. The ballast only responds to commands addressed to it; therefore, the wiring topology is simple: a pair of wires transmit the signals to the fi xtures. The DALI control wiring may be daisy-chained from fi xture to fi xture; they may be wired in a star fashion, all going back to a single wiring point; or any combination of the two. DALI ballasts are also capable of sending digital codes as well. It is possible to send a query to the ballasts on a signal bus to determine if any lamps have failed, or if there are any other problems with the system.