DALI communication

The DALI telegram rate limit can optionally be activated. Firstly, it is then possible to extend the period of time between DALI telegrams. Secondly, the initialisation behaviour of the gateway can be influenced. By using the DALI telegram rate limit, it is possible to adapt the communication behaviour of the gateway to problematic or non-DALI-conformant operating devices to a great extent.

The DALI telegram rate limitation is activated and configured separately for the DALI systems on the parameter page "DALI System... -> General".

Delay time after mains voltage return

After the mains voltage supply is switched on, DALI operating devices usually require different lengths of time to initialise themselves and thus to react to commands of the gateway, depending on their type. To ensure that no commands of the gateway to the operating devices are lost after mains voltage return - because they are still initialising - it is possible to activate a delay as an option. This delay is defined by the "Delay after mains voltage return" parameter, which is available on the parameter page "DALI System... -> General" with activated DALI telegram rate limitation, defined within the range of 1...30 seconds.

The delay time after the mains voltage returns delays the start of the application of the DALI gateway after the mains voltage supply is switched on as well as after an ETS programming operation and thus delays the execution of the configured behaviour after the bus voltage returns and all other automatic reactions (e.g. status telegrams) after a device reset. No DALI telegrams are transmitted by the gateway in this state. "- -" is displayed on the 7-segment display on the front panel of the device in order to signal that the device is not yet ready for operation.

KNX communication is also possible during the delay time. This allows groups and single devices as well as scenes to be controlled and commands specified. However, these are only executed once the delay time on the DALI page has elapsed. Only the last command related to a group, a single device or a scene is ever executed!

If KNX telegrams for groups or single devices are received during the initialisation of the gateway, the device will execute the command most recently specified and not the configured behaviour after the bus voltage returns!

The delay time after the mains voltage returns is not required if the initialisation time of the DALI operating devices is shorter than that of the gateway. In this case, the parameter should be set to the smallest value "1" or the DALI telegram rate limitation should be deactivated. If the operating devices initialise more quickly than the gateway, they will activate the programmed "power-on level" before the gateway transmits other brightness commands. After mains voltage return, this allows the observation of short-time changes to the brightness states in the DALI system.

Should only the mains voltage supply of the gateway fail, the operating devices will set themselves to the "System Failure Level". After the mains voltage supply returns, the gateway - once the delay has elapsed - then transmits commands to the DALI page in accordance with the configured behaviour ("Behaviour after bus voltage return") or the last KNX specification.

Time delay between two DALI telegrams

According to the valid DALI standard IEC 62386 ed. 2, pauses of at least 13.5 ms must be maintained between the transmissions of individual DALI commands to the operating devices. Optionally, to reduce the telegram load for the DALI operating devices, and thus reduce the likelihood of errors on the part of some electronic ballasts, it is possible to increase the pause time between commands of the DALI gateway to the operation device. This results in a telegram rate limitation, which can be adapted separately by the parameter "Minimum time delay between two DALI commands" on the parameter page "DALI system... -> General" can be customised. For this parameter to be visible, the DALI telegram rate limitation must be activated on the same parameter page.

Extending the pause time between the DALI commands gives the operating devices more time to react to the commands of the gateway. However, this also delays the reaction time of the overall DALI system when controlled by KNX telegrams and also during DALI commissioning or a DALI test! Particularly long delay times should therefore be avoided as far as possible.

The approved pause time between commands from the gateway to the DALI operating devices and the matching response is within a range of 5.5...10.5 ms. This time period is required by the operating devices and cannot be influenced by the gateway.