Transmission length

The approximate transmission length can be determined from the bit length and the structure of the data frame. For further (simplified) consideration, a mean settling time of 17.0 ms is used for the forward frames (FF), and a mean settling time of 8 ms for the backward frames (BF). Between the two DALI commands sent within 100 ms (send-twice), a settling time of 14.1 ms is used.

The number of bits results from the number of data bits (8, 16 or 24) plus the start bit. Thus 9, 17 or 25 bits are transmitted with the respective frames.

16-bit frame without backward frame:
17.0 ms + (17 x 0.833 ms) = 31.2 ms.

16-bit frame with backward frame:
17.0 ms + (17 x 0.833 ms) + 8.0 ms + (9 x 0.833 ms) = 46.7 ms.

16-bit frame send-twice:
17.0 ms + (17 x 0.833 ms) + 14.1 ms + (17 x 0.833 ms) = 59.4 ms.

24-bit frame without backward frame:
17.0 ms + (25 x 0.833 ms) = 37.8 ms.

24-bit frame with backward frame:
17.0 ms + (25 x 0.833 ms) + 8.0 ms + (9 x 0.833 ms) = 53.3 ms.

24-bit frame send-twice:
17.0 ms + (25 x 0.833 ms) + 14.1 ms + (25 x 0.833 ms) = 72.8 ms.

The following table lists the average transmission lengths of the individual frames. This results in a maximum possible number of frames per second. The PLC program should be designed in such a way that the number of frames always falls below the maximum.