DALI standard

AN1756

6/10

3

DALI standard

3.1

Introduction

DALI is an acronym for Digital Addressable Lighting Interface, standardized as IEC 929.

DALI is the new interface standard for lighting controls solutions defined by the lighting

industry. AG-DALI is the “Digital Addressable Lighting Interface Working Group” established

for joint promotion and application of the DALI Standard by leading manufacturers and

institutions in the field of digital addressing of lamps and/or luminaires. For more

information, refer to document 3 referenced in Section 4.

3.2

DALI standard protocol

The DALI protocol uses the bi-phase Manchester asynchronous serial data format. All the

bits of the frame are bi-phase encoded except the two stop bits.

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The transmission rate is about 1.2 kHz. The bi-phase bit period is 833.33uS ±10%.

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A forward frame consists of 19 bi-phase encoded bits:

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1 start bit (0->1: logical ’1’)

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1 address byte (8-bit address)

–

1 data byte (8-bit data)

–

2 high level stop bits (no change of phase)

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A backward frame consists of 11 bi-phase encoded bits:

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1 start bit (0->1: logical ’1’)

–

1 data byte (8-bit data)

–

2 high level stop bits (no change of phase)

A forward frame consists of 19 bi-phase encoded bits: 1 start bit (logical ’1’), 1 address byte

and 1 data byte. The frame is terminated by 2 stop bits (idle). The stop bits do not contain

any change of phase.

A backward frame consists of 11 bi-phase encoded bits: 1 start bit (logical ’1’) and 1 data

byte. The frame is terminated by 2 stop bits (idle). The stop bits do not contain any change

of phase.

The transmission rate, expressed as a bandwidth, is specified at 1.2 kHz for the forward

channel and for the backward channel.

The settling time between two subsequent forward frames is 9.17 ms (minimum).

The settling time between forward and backward frames is between 2.92 ms and 9.17 ms. If

a backward frame has not been started after 9.17 ms, this is interpreted as “no answer”.

In the event of code violation, the frame is ignored. After a code violation has occurred, the

system is ready again for data reception.