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Blocks Inside Subsystems with Event-Based Inputs

When an atomic subsystem or function-call subsystem has event-based input signals, the subsystem has a restricted set of possible contents. The subsystem can contain:

  • Blocks having a Sample time parameter of -1, which indicates that the sample time is inherited from the driving block.

  • Blocks that always inherit a sample time from the driving block, such as the Bias block. To determine whether a block in one of the Simulink® libraries inherits its sample time from the driving block, see the "Characteristics" table near the end of the block online reference page.

  • Blocks whose outputs cannot change from their initial values during a simulation. For more information, see Constant Sample Time in the Simulink documentation.

The subsystem cannot contain:

  • Continuous-time blocks

  • Discrete-time blocks with a Sample time parameter value that is positive and finite.

In some cases, you can work around these restrictions by entering a Sample time parameter value of -1 or by finding a discrete-time analogue of a continuous-time block. For example, instead of using the continuous-time Clock block, use the discrete-time Digital Clock block with a Sample time parameter value of -1.

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