Digital Addressable Lighting Interface
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The Digital Addressable Lighting Interface (DALI) is a digital protocol for the controlling of lighting in buildings, such as electrical ballasts and dimmers.
DALI was established as a successor for the still market dominating 1-10v and an open standard rival to Digital Signal Interface (DSI), on which it is based. DALI is standardized in accordance with International Electrotechnical Commission (IEC) 60929, standard for fluorescent lamp ballasts.
Each piece of operating equipment with a DALI interface can be communicated with over DALI individually. Using a bi-directional data exchange, a DALI controller can query and set the status of each light. As a standalone system, DALI can be operated with a maximum of 64 devices. Alternatively, DALI can be used as a subsystem via DALI gateways.
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[edit] Advantages
- DALI is an open standard not exclusively owned by a single company.
- It only requires one bus wire for up to 64 devices.
- Because it uses Differential Manchester encoding it doesn't matter which way around the signal cable is wired, this makes installation more foolproof.
- It doesn't insist the cabling is a "daisy-chain", "stars" and "T's" are perfectly acceptable giving the installers flexibility
[edit] Disadvantages
- Each device gives itself a random number to identify itself, which makes initial installation and replacing faulty devices confusing as there is no indication which device is which, until the operator sends out test signals and looks to see which device responds.
- Being restricted to 64 addresses (six bits), DALI cannot be used in large installations without using another technology to workaround the limitation.
- Its slow communication speed (1200 bits per second) can mean a visible delay in large installations with a lot happening.
- The EEPROM where presets are stored can only be rewritten 100 times
- There are few affordable portable test tools for it.
[edit] External links
[edit] Organisations
- AG-DALI, a working group set up by leading manufacturers and institutions in the field of digital lamp/luminaire control to promote DALI technology and applications
