Chapter 14 Sequential Function Chart During the first scan cycle, Action1 is executed when STEP_1 is activated. If M1 is ON, M2 will be ON. Action1 is executed only when STEP_1 is activated during the first scan cycle. Besides, the system will not execute a final scan after the execution of Action1 stops. Consequently, the state of M2 will not change even if the state of M1 changes. P0 (Falling Pulse) The P0 action associated with a step is executed only when the step is inactivated during the first scan cycle. Besides, the system will not execute a final scan after the execution of the P0 action stops.
Consequently, although an action where the instruction OUT or TMR is used is allowed to be qualified by P1, a warning appears when the program is compiled. When STEP_1 is activated, Action1 is not executed. Action1 will not be executed until Tran1 is true. If M1 is ON, M2 will be ON. Action1 is executed only when STEP_1 is inactivated during the first scan cycle. Besides, the system will not execute a final scan after the execution of Action1 stops. Consequently, the state of M2 will not change even if the state of M1 changes. 14-19