Question
The DALI bus uses a polarity-free twisted pair (no + / - orientation), with Manchester coding at 1 200 baud over a nominal 22.5 V DC supply, and is allowed to share the same multi-core cable as the 230 V mains feeding the luminaires.
DALI-2LearnArchitectureMedium
Answer
True
The DALI physical layer is polarity-free (unlike KNX TP1, which is polarised), uses Manchester coding with one bit equal to 833 microseconds, runs at 1 200 bit/s (slow but ample for lighting), and operates at a nominal 22.5 V DC (16-22.5 V usable). It may share a multi-core cable with 230 V mains, in contrast to KNX, which mandates 4 kV separation. The maximum bus length is 300 m with a conductor cross-section of at least 1.5 mm squared.
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