User`s guide

Delay and Latency
3-87
input. This delay is directly related to the time elapsed on the Simulink timer
during that block’s execution.
The algorithmic delay of a particular block may depend on both the block’s
parameter settings and the general Simulink settings. To simplify matters, it
is helpful to categorize a block’s delay using the following levels:
•Zero algorithmic delay
•Basic algorithmic delay
•Excess algorithmic delay (tasking latency)
The following sections explain the different levels of delay, and how the
simulation and parameter settings can affect the level of delay that a
particular block experiences.
Zero Algorithmic Delay
The FFT block is an example of a component that has no algorithmic delay; the
Simulink timer does not record any passage of time while the block computes
the FFT of the input, and the transformed data is available at the output in the
same time step that the input is received. There are many other blocks that
have zero algorithmic delay, such as the blocks in the Matrices and Linear
Algebra libraries. Each of those blocks processes its input and generates its
output in a single time step.
In Chapter 5, “DSP Block Reference,” blocks are assumed to have zero delay
unless otherwise indicated. In cases where a block has zero delay for one
combination of parameter settings but nonzero delay for another, this is noted
on the block’s reference page.
Example: Zero Algorithmic Delay. Create the model below to observe the operation
of the zero-delay Normalization block.