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FIGURE 1: The image shows the driver is permanently powered in the Zhaga architecture. (Source: TE Connectivity)
The D4i digital communication protocol was created through a liaison
between Zhaga and the DALI Alliance. This protocol has baked in
arbitration, creating a hierarchy between two control devices on
the same bus. As shown in the Zhaga architecture image, the
driver is now permanently powered (Figure 1). Typically, an
AUX 24VDC PSU is built into the driver, although a separate
PSU is allowed. This means that a 24V rail is always
available, creating opportunities for communication and
sensor-node designs that can be used at any time of day.
Wiring becomes simplified with the two control devices
and the driver connected to the same communication
bus.
This edition also defined the power budget that
the driver is required to deliver from both the
AUX power supply and the powered DALI
bus power supply—as well as the power
that different types of control devices are
allowed to pull from the system. This is
all controlled through a certification
program. Drivers are certified D4i by
the DALI Alliance, while luminaires and
control devices are certified Zhaga-
D4i by the Zhaga Consortia.
