Features and differences between DALI and DALI 2 protocols

DALI PROTOCOL

HISTORY OF THE DALI STANDARD

DALI stands for "Digital Addressable Lighting Interface". DALI is a protocol for the digital control of lighting equipment such as transformers, electronic ballasts, LED drivers and relay modules.

The DALI protocol was first developed in the late 1990s by Tridonic company in collaboration with well-known equipment manufacturers such as Helvar, Osram, Erco, Insta, Lutron and Philips to control and control lighting systems. This development was carried out to replace the "1-10V" analog control, which is widely used even to this day. Today, these manufacturers form the DALI Activity Group, which promotes the use of the DALI standard and ensures its continued development.

DALI Activity Group monitors compliance with the standard, certifies equipment from different manufacturers and guarantees its compatibility. Thus, the presence of the DALI Alliance logo on the body of the device means that it has passed these tests and received the appropriate certificate.

Currently, the DALI protocol is internationally standardized under IEC 62386, and until 2009 it was defined by EN 60929. In 2017, the DALI Activity Group was renamed the Digital Illumination Interface Alliance (DiiA).

DALI STANDARD VERSIONS

Since November 2014, a new version of the DALI standard has been available. Version 2 - also called "DALI-2". DALI-2 is an updated and improved version of the DALI lighting control protocol that includes more functionality. It also describes other types of devices that were not clearly described in earlier versions of the standard. Examples of such devices are motion sensors, control panels, switches, light sensors and other controllers. Previously, different equipment manufacturers produced them based on their own ideas and using their own specifications. This led to complete incompatibility of these devices within the same installation. The updated DALI-2 protocol has filled in all these gaps by paying more attention to device compatibility.

These devices are now described in additional DALI specifications and instructions:

• IEC 62386-103 - General requirements for control devices
• IEC 62386-301 - Manual controls (buttons)
• IEC 62386-302 - Absolute control devices (regulators)
• IEC 62386-303 - Motion and presence detectors
• >IEC 62386-304 - Light sensors

In the figure below, those specifications that have been edited with the update of the standard are marked in red.

IEC 62386 STANDARD

SYSTEM DESIGN AND TOPOLOGY

The DALI system is based on ease of operation, convenience and ease of installation, as well as high flexibility in organizing the network structure.

 DALI systems can be installed using a conventional power cable, for example, VVGngLS 5x1.5 (L, N, PE, DA+, DA-), two cores of which are used for the DALI line, and the remaining three cores are used for power transmission. It should not be forgotten that the maximum allowable voltage drop on the DALI bus should not exceed 2 volts and the total current consumption should not exceed 250 mA. Only one DALI power supply is allowed per DALI line. And it must be taken into account that gateways to other systems and protocols (for example, DMX-DALI or KNX-DALI Gateway) have built-in power supplies. Therefore, installing them at the same time can lead to problems.

DATA TRANSMISSION AND TELEGRAMS

The DALI protocol uses a "Manchester" code to transfer logical states.

GROUP CONTROL CONCEPT AND LIGHT SCENE

Each DALI device can store 16 different lighting scenes so that pre-configured lighting presets for a room can be recalled (for example "presentation" in a conference room or "morning" in a wellness center). The brightness values for each of the 16 scenes are stored directly in the actuators (dimmers, sequencers). As soon as the device receives the "Run Scene 1" command, for example, it increases or decreases the brightness to the value stored in memory. The parameter for adjusting the dimming time when recalling a scene is also stored in the device and can be changed.

                                                                                                  Light stage "Bright light" Light stage "Cinema"

The DALI system defines 3 types of control commands: group, individual and broadcast. One DALI line can control luminaires in up to 16 groups. A group is a number of luminaires performing the same function at the same time. A group number can be flexibly assigned to each DALI device. One DALI device can be a member of only one group or several groups. During group control, a control telegram is sent to the bus containing the number of the group that should execute this command. Devices that are part of groups with a different number simply ignore this telegram. All this reduces the amount of cabling required and greatly increases the flexibility of lighting group assignments compared to non-addressable systems. By contrast, lighting groups are always hard-wired in non-addressable systems.

In addition to group control, DALI devices can be controlled individually using their own individual address. Those, by connecting to the line, you can control each of them separately. In this case, the destination address of the telegram will not be a group address, but an individual one. Individual control, as well as group control, can provide the current status of luminaires and supports the following range of commands:

MAIN DIFFERENCES DALI-2 FROM DALI

In the old DALI system, commands from sensors and controllers are processed directly by the actuators. With the update of the standard, new application controllers were released, and now control devices can be combined. For example, a motion sensor with a built-in light sensor and a binary input for an external switch contains 3 instances of control devices (Instances).

Such devices can be combined into control groups under the following conditions:

Thus, in the new DALI-2 system, the input and control devices are no longer directly connected to the actuators (LED drivers or Ballasts). Instead, the commands are first processed by a new element, the Application controller, and then sent to the drivers. The application controller provides data transfer between control devices (sensors, switches, etc.) and the actuator. The application controller can also be built directly into the controller. In this case, an additional external controller is not required.

Another significant innovation of the DALI-2 connection is the ability to detect collisions on the data bus. If a collision occurs and as a result of the loss of the telegram, it will be sent again. In this case, the command can be sent again if it was lost as a result of a collision. The application controller clearly monitors this process.

• BF - Backward Frame
• FF - Forward Frame

DALI AND DALI2 COMPATIBILITY

DALI and DALI-2 actuators can be used together. But keep in mind that DALI-2 functionality is limited when working with DALI-1 drivers. The reason is that the DALI-2 protocol defines new commands that cannot be interpreted by DALI devices. On the other hand, DALI-2 control devices should under no circumstances be mixed in line with older DALI input devices, as they will not be recognized by the application controller.

The user of the system is not dependent on the equipment of a particular manufacturer, since DALI is an open protocol and is controlled by the DiiA alliance.

The data bus is not subject to interference and can be laid in close proximity to power supply lines;
Luminaires can be controlled flexibly by multiple controllers regardless of their location and number;
All important parameters and settings are stored in the memory of DALI devices and in case of loss and subsequent restoration of power, the system continues its work (address, belonging to groups, operation scenarios, dimming speed, brightness levels);
The presence of feedback and diagnostic functions allows you to receive information about the status of DALI devices, as well as the state of the lamp or lamps and lamp ballasts;
Significant reduction in operating costs on large properties. For example, offices, business centers, public and administrative buildings, as well as cafes and restaurants;
Fast installation and simplification of cable installation;
Possibility of easy integration with other standards and protocols. For example: LON, BACnet, KNX, DMX512 or Modbus.

Cons:

• Low data transfer rate, which may be negatively perceived by the user when integrating into other systems.
• Impossibility of control of any other systems, except lighting system;
• Very poor choice of user interfaces and controls (switches, panels, motion sensors, etc.)

HOW TO OVERCOME SOME CONS?

The last 2 disadvantages can be easily dealt with by combining DALI, for example, with KNX. This can be done using special gateways, which are produced by all major manufacturers of KNX equipment. The necessary controllers are available from ABB, GIRA, JUNG, MDT, Schneider Electric, Zennio and other less well-known manufacturers.
However, only some of them (ABB, GIRA, JUNG, MDT) support the latest specifications of the DALI-2 standard. There are also Broadcast KNX-DALI gateways. They are very easy to put into operation, as they require significantly less setup effort on the KNX side and no setup effort on the DALI side. This is due to the fact that the combination of light groups in them occurs strictly according to the principle: one line - one group, and the number of such groups can vary from 4 to 8 depending on the manufacturer and model. And all control commands to the DALI bus are transmitted using broadcast (broadcast) telegrams.
Some models of KNX-DALI Broadcast gateways.