DESIGN CASEA simple state diagram is shown in Figure 20.1 An Example State Diagram. 
Figure 20.1 An Example State Diagram The state diagram is implemented in FBD form in Figure 20.1 An FBD Implementation of a State Diagram Using Transition Equations. In this case the transition equations approach was used, although other methods are equally applicable. The transitions ’STA_TO_STB’, "STB_TO_STA’, ’STB_TO_STC’, and ’STC_TO_STA’ are calculated first. These are then used to update the states ’STA’, ’STB’, and ’STC’. Additional program steps could then be added to drive outputs. 
Figure 20.1 An FBD Implementation of a State Diagram Using Transition Equations |