Discrete System Tab

The Run Properties Editor can be used to edit the sample frequency of a discrete-time system in the model. 20-sim automatically detects the existence of discrete systems in a model. For each discrete system, one extra tab (Discrete System) is shown in the Run Properties Editor.

The Discrete Systems tab.

Items

Identified with: Each discrete system in a model is assigned a unique identifier. 20-sim detects discrete systems by looking for discrete functions and variables:

When a function has been found, the elements of the corresponding discrete system are identified by propagation of the equations. In order of appearance in the model, the discrete system is assigned a unique identifier:

sample -> the variable that is assigned to the output of the sample function.
hold -> the variable that is assigned to the output of the hold function.
previous -> the discrete state corresponding with the previous function.
next -> the discrete state corresponding with the next function.
sampletime -> the variable that is equal to the sampletime.

Timing (Standard): Each discrete system has a default sample frequency of 1 Hz. You can change this frequency to any desired value:

Discrete Time Interval (s): The sample interval (in s) of the discrete system
Frequency (Hz): The sample frequency (in Hz) of the discrete system.

Timing (Advanced): For discrete-time control loops that interact with physical continuous-time systems through sensors (analog to digital) and actuators (digital to analog) the specific timing is important. Click the Advanced button to specify this timing.