Manual parameterisation and monitoring

The DALI interface provides a great number of different commands and parameters which essentially emerge in the following fashion:

  • Highly simple control devices (plug and play) usually only access direct dimming commands (dimming values) in broadcast mode. There is no initialisation.

  • Higher-performance control devices facilitate addressing of control gear units. They utilise a greater range of commands. Pre-settings via DALI parameters are also utilised. Pre-settings are usually implemented automatically when initialising the system and are optimised for the intended application case.

  • Universal-use, freely programmable control devices provide great user freedom in implementing complex and customised control tasks. The full command and parameter range of the DALI interface is available to the user. The setup of expedient pre-settings and tailored functions is up to the skills of experts.

Figure 3.246: DALI monitoring: The repeat rate determines a control gear unit's behaviour after an interruption in mains power (e.g. switching via mains switch) if the control device is still supplied with mains voltage.
Note: In lighting installations with repeated mains interruptions for emergency lighting test functions, a recurring DALI signal should be implemented to avoid keeping emergency lights at power-on level.

(a) “Quasi”-permanent DALI signal. Transmission of a direct dimming command: 7/s.
If control gear units are switched off and back on via supply voltage (230 V), they immediately receive a DALI signal and start up at the dimming level set at the control device.

(b) Recurring DALI signal. Transmission of a direct dimming command: 1/5s.
If control gear units are switched off and back on via supply voltage (230 V), they start up at the power-on level set at the control gear unit and adopt the dimming level set at the control device upon receipt of the next DALI signal (at the latest after 5 seconds).

However, there are some situations where manual parameterisation is a sensible option for non-experts as well. This requires a DALI programming device with integrated or external DALI power supply. After removing an existing DALI control device from an installation, the DALI programming device can be connected and commissioned.

A useful DALI parameter that can occasionally be helpful outside of DALI control is the system failure level. It facilitates determining the dimming level the control gear unit adjusts to if no DALI voltage is present. This parameter can be set in particular when a luminaire is intended to be set permanently to a defined dimming level below 100% operation. In this case, the desired level can be manually set once and stored in the control gear unit as system failure level so that a control gear unit is not required for further operation. As the case may be, the power-on level should be set to the identical value since some control gear units start the connected light source at this dimming level initially when mains voltage is applied before the interface status is evaluated.

Another important parameter in many applications is the repeat rate of transmission of the most recently set dimming value. Some DALI control devices only transmit DALI commands once. After that, no DALI signal is transmitted until the next change in dimming value. If a control gear unit is disconnected from the DALI system and re-connected during this period, e.g. in the course of automatic emergency light function testing, it remains at power-on level until the next change in overall dimming level.

Another parameter frequently utilised by many users is fading time. Fading time should be defined with care if it is not predetermined in system initialisation. Particularly in DALI applications where manual dimming is also intended, it is important not to set an overly long fading time. Otherwise the dimming process may trail manual operation, e.g. in the following cases:

  • Dimming via push-button: The speed of dimming value changes via push-button should not be greater than the actual dimming executed based on fading time. Otherwise, the dimming process will continue even after releasing the push-button. This makes the exact setting of a desired dimming level difficult and inconvenient.

  • DALI “potentiometer”: A fading time should not be set since rotation is possible at arbitrary speeds.

Other frequently used parameters are minimum level and maximum level. They serve to limit the luminaire's dimming range. However, it is important to consider that many control gear units overwrite these parameters during initialisation or might set it back to factory settings during application in the context of a general reset. With regard to this, making safety-relevant pre-settings (overload protection, escape route lighting levels etc.) via DALI parameters should be avoided as a matter of principle if a collision with functions of one (currently or to-be) connected control gear units cannot be excluded.

Besides manual parameterisation, DALI programming devices usually offer a monitoring function for the purpose of which the device is passively connected (without a DALI power source) to an active DALI system to analyse data traffic in the DALI line. This facilitates the determination of e.g. details of the implementation of functions realised by using DALI commands and parameters which are relevant for application cases but cannot be gathered from the system's documentation.

For instance, e.g. the transmission repeat rate for direct dimming commands might be of interest if parts of the lighting installation are intended to be switched off via disconnection from the mains voltage during permanent operation (see figure).