DiscreteLibrary of discrete input/output blocks with fixed sample period 
Ideal sampling of continuous signals 

Zero order hold of a sampleddata system 

First order hold of a sampleddata system 

Unit Delay Block 

Discrete Transfer Function block 

Discrete State Space block 

Triggered sampling of continuous signals 

Compute maximum, absolute value of continuous signal at trigger instants 
This information is part of the Modelica Standard Library maintained by the Modelica Association.
This package contains discrete control blocks with fixed sample period. Every component of this package is structured in the following way:
A sampled data system may consist of components of package Discrete and of every other purely algebraic input/output block, such as the components of packages Modelica.Blocks.Math, Modelica.Blocks.Nonlinear or Modelica.Blocks.Sources.