A conditionally executed subsystem is an atomic subsystem that allows you to control its execution with an external signal. The external signal, called the control signal, is attached to the control input port. Conditional subsystems are useful when you create complex models that contain components whose execution depends on other components.
Simulink® supports these types of conditional subsystems:
Enabled Subsystem — Executes at each time step while the control signal is positive. Execution starts at the time step when the control signal crosses zero from the negative to the positive direction. See Enabled Subsystems.
Triggered Subsystem — Executes each time a trigger event occurs. A trigger event can occur on the rising or falling edge of a continuous or discrete trigger signal. See Triggered Subsystems.
Enabled and Triggered Subsystem — Executes once at the time step when a trigger event occurs and the enable control signal has a positive value. See Enabled and Triggered Subsystems.
Function-Call subsystem — Executes each time a function-call event occurs. A Stateflow® chart, Function-Call Generator block, or an S-function block can provide function call events. See Using Function-Call Subsystems.