actions inside a program unit that influence the state of another program unit. Non-standard extensions to the language include macroactions: i.e. SFC is an inherently parallel language in that multiple control flows - Program Organization Units (POUs) in the standard's parlance - can be active at once. language rather than the TCL syntax used in the Sequence Debug Display. It is also possible to insert LD ( Ladder Diagram) actions inside an SFC program (and this is the standard way, for instance, to work on integer variables). stops and waits for an operator response. It is one of the five languages defined by IEC 61131 3 standard.
An SFC rule states that if two steps have an N action on the same target, the variable must never be reset to 0. (SFC) is a graphical programming language used for PLCs.
Apart from the obvious meaning of Set and Reset, an N action ensures that its target variable is set to 1 as long as the step is active. When a transition is passed, all steps above are deactivated at once and after all steps below are activated at once.Īctions associated with steps can be of several types, the most relevant ones being Continuous (N), Set (S) and Reset (R). Steps are activated when all steps above it are active and the connecting transition is superable (i.e. It was activated during a scan cycle and not deactivated since.It is an initial step as specified by the programmer.A step can be active for one of two motives: Actions are only executed for active steps. We show how these charts can be used for robotic. Steps in an SFC diagram can be active or inactive. Sequential function charts have been sued to specify control programs for programmable logic controllers. Directed links between steps and transitions.Transitions with associated logic conditions.Basic Batch SFC, with important elements labelled