DALI-2 supports several application controllers active on the same bus (multi-master), with an arbitration mechanism that prevents conflicts when two controllers try to command the same control gear at the same time.

Multi-master operation is a DALI-2 addition: DALI v1 was strictly single-master (one controller per bus), whereas DALI-2 allows multiple controllers with CSMA/CA arbitration. A typical use case is running a dedicated application controller for everyday control alongside a KNX/DALI gateway for supervision on the same bus, without conflicts. Arbitration is based on collision detection and a random back-off delay, enabling more flexible architectures.

Even though the bus supports multi-master, give each controller a clearly separated role (one writes, the others read); two controllers commanding the same gear concurrently is technically allowed but operationally confusing.