How to Add Transitions in Stateflow: Simple Guide

To add transitions in Stateflow, click on the source state, drag the arrow to the target state, and release. Then, double-click the transition arrow to enter the condition or event that triggers the transition using condition or event syntax.

Syntax

In Stateflow, a transition is defined by an arrow connecting two states. You specify the trigger condition or event in the transition label using this pattern:

• [condition] — transition occurs when the condition is true.
• event — transition occurs when the event happens.
• event[condition] — transition occurs when the event happens and the condition is true.

Example: buttonPress && x > 5 means the transition triggers when buttonPress event occurs and x is greater than 5.

plaintext

state1 --> state2 : event[condition]

Example

This example shows how to add a transition from Idle state to Active state triggered by an event start and a condition count > 3.

plaintext

chart Idle {
    entry: count = 0;
    during: count = count + 1;
}

Idle --> Active : start[count > 3]

chart Active {
    entry: disp('Active state entered');
}

Output

When the event 'start' occurs and count is greater than 3, the chart transitions from Idle to Active, displaying 'Active state entered'.

Common Pitfalls

• Not specifying a condition or event on the transition, which makes it always trigger immediately.
• Using incorrect syntax like missing brackets around conditions.
• Forgetting to define the event in the model, so the transition never triggers.
• Creating transitions that cause conflicts or loops without exit conditions.

Correct syntax example: event[condition]
Wrong syntax example: event condition (missing brackets)

plaintext

/* Wrong transition syntax */
state1 --> state2 : start count > 3

/* Correct transition syntax */
state1 --> state2 : start[count > 3]

Quick Reference

Transition Element	Description	Example
Event	Triggers transition when event occurs	start
Condition	Triggers transition when condition is true	[x > 5]
Event with Condition	Triggers when event occurs and condition is true	start[x > 5]
No Condition or Event	Immediate transition (usually not recommended)

Key Takeaways

Add transitions by dragging from source to target state in Stateflow.

Specify triggers using event names and conditions in brackets on the transition label.

Use correct syntax: event[condition] to avoid errors.

Always define events in your model to ensure transitions trigger.

Avoid transitions without conditions or events to prevent unexpected behavior.