The state diagram (tutorial)

A hands-on example builds a statechart incrementally, following the basic workflow of modeling event-driven systems. The example ("fansController") maintains air temperature in a system using a controller that operates two fans:

• Fan 1 turns on if air temperature rises above 90 degrees.
• Fan 2 provides additional cooling if air temperature rises above 130 degrees.

Building this chart teaches the following elements:

Exclusive (OR) states

States representing mutually-exclusive modes of operation — no two exclusive (OR) states can be active/executing at the same time. Represented graphically by a solid rectangle. The fansController example uses six exclusive (OR) states to represent the combinations of fan-on/off conditions across the two temperature thresholds.