Check undefined subsystem initial output

Description

Specify whether to display a warning if the model contains a conditionally executed subsystem in which a block with a specified initial condition drives an Outport block with an undefined initial condition

Category: Diagnostics

Settings

Default: On

On: Displays a warning if the model contains a conditionally executed subsystem in which a block with a specified initial condition drives an Outport block with an undefined initial condition.
Off: Does not display a warning.

Tips

This situation occurs when a block with a specified initial condition, such as a Constant, Initial Condition, or Delay block, drives an Outport block with an undefined initial condition (Initial output parameter is set to []).
Models with such subsystems can produce initial results (i.e., before initial activation of the conditionally executed subsystem) in the current release that differ from initial results produced in Release 13 or earlier releases.
Consider for example the following model.
This model does not define the initial condition of the triggered subsystem's output port.
The following figure compares the superimposed output of this model's Step block and the triggered subsystem in Release 13 and the current release.
Notice that the initial output of the triggered subsystem differs between the two releases. This is because Release 13 and earlier releases use the initial output of the block connected to the output port (i.e., the Constant block) as the triggered subsystem's initial output. By contrast, this release outputs 0 as the initial output of the triggered subsystem because the model does not specify the port's initial output.