Time domains comprise blocks which run with the same periodicity. Each time such a time domain executes everyone of its blocks runs in a predetermined way. A control system may have one or several time domains running with different periods.

Each signals's value will be marked with a timestamp, indicating the exact time corresponding to the value of the represented physical quantity. This is for instance when the value was captured or generated.

The timestamp can be changed by blocks, if the algorithm influences the time base of the signal. This is typically the case in differentiation, integration or filtering.

The timestamp is needed for instance for operations per-formed between signals, which generally are not correct if the values don’t base on the same point in time. It also can be used for compensating any jitter or dead times.