Chapter 14 Sequential Function Chart 14.2.6 Qualifier of an Action In ISPSoft, users can define the execution of an action by qualifying the action. However, users can not qualify the actions in the program in a DVP series PLC. Consequently, the actions in the program in a DVP series PLC are N actions. The step name is displayed here. Users can select qualifiers for the actions associated with the step. Users can specify qualifiers related to time. Users can select actions which are qualified. Users can make comments on the step. 14.2.6.1 Qualifier Types N (Normal) When a step is activated, the N action associated with the step is executed.
When the step is inactivated, the system executes a final scan to disable all the outputs in the N action. However, the outputs which use the instructions similar SET are not disabled. The actions in the program in a DVP series PLC are N actions. S (Set) When a step is activated, the S action associated with the step is executed. Even if the step is inactivated, the S action will still be executed. When STEP_1 in the figure below is activated, Action1 and Action2 are executed. When Tran1 is true, STEP_1 becomes inactive. Once STEP_1 is inactivated, the execution of Action1 will stop, the system will execute a final scan, and Action2 will still be executed. 14-15