Active step

After calling the SFC POU, the Action (surrounded by a double border) belonging to the initial step is executed first. A step, whose action is being executed, is called active. In Online mode active steps are shown in blue.

In a control cycle all actions are executed which belong to active steps. Thereafter the respective following steps of the active steps become active if the Transition / Transition condition of the following steps are TRUE. The currently active steps will be executed in the next cycle.

Note

If the active step contains an output action, this will only be executed during the next cycle, provided that the transition following is TRUE.

Note the possibility to use Implicit variables in SFC for scanning the status and time of steps or actions.