CHAPTER Modeling Event-Based Behavior with State Machines 11 This chapter describes how to use state machines to model the behavior of blocks as they respond to internal and external events. 11.1 OVERVIEW Typically state machines are used in SysML to describe the state-dependent behavior of a block throughout its life cycle in terms of its states and the transitions between them. A state machine for a block may be started, for example, when it initiates power up, and then transition through multiple states in response to different stimuli, and terminate when it completes power down. In each state, the block may perform different sets of actions. The state machine defines how the block's behavior