Before you start building a chart, you identify system attributes by answering these questions:
What are your interfaces?
What are the event triggers to which your system reacts?
What are the inputs to your system?
What are the outputs from your system?
Does your system have any operating modes?
If the answer is yes, what are the operating modes?
Between which modes can you transition? Are there any operating modes that can run in parallel?
If your system has no operating modes, the system is stateless. If your system has operating modes, the system is modal.
After identifying your system attributes, you can follow a basic workflow for building Stateflow® charts to model event-driven systems: