Online Mode

Statecharts react to events. When an event occurs and as a result a condition is true, a state transition occurs with the next bus cycle clock. You can also configure transitions so that the state transition switches edge-triggered with the corresponding condition. In the implementation, the transition is then flagged with the symbol.

In the Properties → Property view, select the Rising edge option.

At runtime of a statechart, its states are usually executed with the task cycle. However, you can configure a state in such a way that it is executed in-cycle and the state quickly executes all actions within one bus cycle. This kind of state is displayed in red in the implementation.

In the case of functions and methods, the local variables are usually temporary. At runtime, the local variables are not stored, but released, when the POU is exited. As a result, the information about the state of the statechart is not stored. Therefore, a switching behavior controlled by the bus cycle is not possible. For this reason, statecharts in functions or methods are executed in-cycle. So if you implement a method as a statechart, then this diagram is switched quickly. Also in the ToolBox view, only a red state is available.

You can prevent this behavior by declaring instance variables VAR_INST instead of local variables in the function or method. When you exit the method, instance variables are stored in the calling POU (a program or a function block instance). The state transitions are then switched slowly edge-controlled with the bus cycle.

When an application has been downloaded and started, you can monitor its POUs in the monitoring. In the case of POUs in the UML Statechart implementation language, you can graphically monitor which state is active, because the currently active state is marked in blue. The statechart is updated continuously.

You can force variables in the declaration in the Prepared Value column. In the case of Boolean variables, you can also click the monitoring value to do this in the implementation. When a value is prepared, the monitoring value is marked in the upper right corner of the implementation.

You can also monitor the condition variables of transitions in watch lists in online mode.

In the statechart in online mode, you can define breakpoints to halt the execution of the application at these points and to check the variables or watch lists there. In the statechart in online mode, all possible breakpoint positions are displayed as a gray circle. You can click the circle to select and deselect a position. Click Debug → Toggle Breakpoint or press the F9 key to define a selected position as a breakpoint or release it.

In addition, you can resume an application halted at a breakpoint in single steps.

If you do offline editing on an existing statechart, such as changing transitions, conditions, priorities, actions, or names, then you can download the diagram to the controller with an online change when you log in. The diagram does not require reinitialization.

However, when you add, remove, or replace a state or region, the diagram does require reinitialization. This also applies to changes to implicit states, such as the Selection element or if you select the Abortable implementation condition in the properties dialog of a statechart. Then log in to the controller with a download.