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Check runtime output of execution context


Specify whether to display a warning if Simulink® software detects potential output differences from previous releases.

Category: Diagnostics


Default: Off


Displays a warning if Simulink software detects potential output differences from previous releases.


Does not display a warning.


  • This diagnostic is triggered if the model contains a block that meets the following conditions:

    • The block has a tunable parameter.

    • The block is connected to an output of a conditionally executed subsystem.

    • The block inherits its execution context from that subsystem.

    • The Outport to which it is connected has an undefined initial condition, i.e., the Outport block's Initial output parameter is set to [].

  • Models with blocks that meet these criteria can produce results when the parameter is tuned in the current release that differ from results produced in Release 13 or earlier releases.

    Consider for example the following model.

    In this model, the tunevar S-function changes the value of the Gain block's k parameter and updates the diagram at simulation time 7 (i.e., it simulates tuning the parameter).

    The following figure compares the superimposed output of the model's Pulse Generator block and its Gain block in Release 13 and the current release.

    Note that the output of the Gain block changes at time 7 in Release 13 but does not change in the current release. This is because in Release 13, the Gain block belongs to the execution context of the root system and hence executes at every time step whereas in the current release, the Gain block belongs to the execution context of the triggered subsystem and hence executes only when the triggered subsystem executes, i.e., at times 5, 10, 15, and 20.


This parameter is enabled only if Underspecified initialization detection is set to Classic.

Command-Line Information

Parameter: CheckExecutionContextRuntimeOutputMsg
Value: 'on' | 'off'
Default: 'off'

Recommended Settings

DebuggingNo impact
TraceabilityNo impact
EfficiencyNo impact
Safety precautionOn

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