Technical notes, queries & updates

What are instance types?

An instance is a part of an input device, which is a product that provides information to the DALI system.

An example is a push-button panel with 8 buttons. Each button is one instance, giving 8 in total in the same product. These will implement IEC 62386-301 (push-button), which is instance type 1. Similarly, an occupancy sensor implements IEC 62386-303, which is instance type 3.

It is common for input devices to implement more than once instance. A sensor may implement an occupancy sensor and a light sensor in the same product. These are instance types 3 (Part 303) and 4 (Part 304).

One control device short address can support multiple instances. In the first example, a push-button panel with 8 buttons would normally use only 1 short address (1 logical unit), which is divided into 8 instances numbered 0-7.

Not all application controllers can support the use of input devices. Check with your application controller supplier, as well as the DiiA product database.

Some application controllers can make use of event messages from input devices, for faster response, whilst some may use polling, especially for slow-changing measurements such as light level.