Model discrete events
Parent Section: component
events begins the events section, which is terminated by an
end keyword. The
events section in a component
file manages event updates. It is executed throughout the simulation.
events section can contain only
when clause serves to update the values of the event variables.
The syntax is
when EventPredicate var1 = expr1; var2 = expr2; ... end
EventPredicate is an expression that defines when an event
occurs. It must be an expression of event data type, as described in Event Data Type and edge Operator.
The variables in the body of the
when clause must be declared as
When the event predicate returns true, all the variables in the body of the
when clause simultaneously get updated to the new values.
when clause can optionally have one or more
when EventPredicate var1 = expr1; var2 = expr2; ... elsewhen EventPredicate var1 = expr3; ... end
else branch in a
when clause is
The following rules apply:
The order of
whenclauses does not matter.
The order of the variable assignments in the body of a
whenclause does not matter because all updates happen simultaneously.
whenclause cannot update an event variable more than once within the same assignments list.
whenclauses may not update the same event variable. You must use an
elsewhenbranch to do this.
The order of
elsewhenbranches matters. If multiple predicates become true at the same point in time, only the branch with the highest precedence is activated. The precedence of the branches in a
whenclause is determined by their declaration order. That is, the
whenbranch has the highest priority, while the last
elsewhenbranch has the lowest priority.
Triggered Delay Component
This example implements a triggered delay component:
component Triggered inputs u = 0; % input signal triggered = 0; % control signal end variables(Event=true) x = 0; end outputs y = 0; end events when edge(triggered>0) x = u; end end equations y == x; end end
When the control signal becomes positive, the event variable
x gets updated to the current value of the input
y outputs the value
x. Therefore, the output signal
gets updated to the current value of the input signal
on the rising edge of the control signal, and then holds that value between
Introduced in R2016a