Transductors - Harel State Charts

Harel state charts expand this even further by allowing more levels of abstraction. They combine Meley and Moore state machines and add additional concepts:

• Hierarchy allows us to be in multiple states of our state machine at once. For instance, we could add another state to our AC diagram - On.

• Parallelism allows two or more separate state machines to work in parallel, yet be displayed on the same diagram. We'd use this if their effects are tied in a way that makes it easier to understand them together.
• Broadcasting allows state machines to communicate with each other by broadcasting certain signals that the other state machine may pick up on. For instance, our AC could have two separate state machines for its fans and its thermostat. But the thermostat should broadcast the change in temperature to the fans so they could decide when to go into standby and when to work.