The Digital Addressable Lighting Interface (DALI) is a standardized protocol designed for digital lighting control, enabling robust, scalable, and flexible lighting networks. One of its core features is the use of short addresses, which allow individual control of devices within the network.
What Is a DALI Short Address?
In a DALI system, each control gear (such as LED drivers or electronic ballasts) is assigned a unique short address. This address enables precise identification and control of individual devices within the network. The addressing scheme allows for up to 64 unique short addresses, facilitating granular control over each device.
Addressing Structure and Encoding
DALI utilizes an 8-bit addressing format. To send a command to a specific device, the short address is converted into an address byte. This is achieved by multiplying the short address by 2 and adding 1, effectively shifting the address and setting the least significant bit to indicate a command. For example, a short address of 5 would be converted as follows:
#define DALI_SHORT_ADDR_TO_ADDR_BYTE(short_addr) (1 + (short_addr << 1))
This method ensures that the device recognizes the incoming data as a command intended for it.
Address Assignment Methods
Assigning short addresses can be accomplished through:
- Automatic Addressing: Utilizing the DALI controller’s automatic addressing feature, the system assigns unique addresses to all connected devices.
- Manual Addressing: Using specialized software or tools, technicians can manually assign or modify addresses for individual devices.
It’s crucial to ensure that each device has a unique address to prevent conflicts and ensure reliable communication within the network.
Grouping and Scene Control
Beyond individual addressing, DALI supports grouping devices and defining scenes:
- Groups: Devices can be assigned to up to 16 groups, allowing simultaneous control of multiple devices.
- Scenes: Up to 16 scenes can be defined, each representing a specific lighting configuration. Devices can store preset levels for each scene, enabling quick transitions between different lighting moods or settings.
This flexibility allows for dynamic lighting control tailored to various environments and user preferences.
Practical Considerations
- System Capacity: A single DALI network supports up to 64 devices. For larger installations, multiple DALI networks or gateways may be necessary.
- Two-Way Communication: DALI’s digital nature allows devices to report status information, such as failures or operational parameters, enhancing maintenance and monitoring capabilities.
- Simplified Wiring: DALI systems use a two-wire bus for both power and data, reducing installation complexity. The wiring is polarity-insensitive, minimizing potential errors.
Conclusion
DALI short addresses are fundamental to the protocol’s ability to provide precise and flexible lighting control. By understanding and effectively managing these addresses, system designers and technicians can create sophisticated lighting environments that are both efficient and adaptable to changing needs.
