Lenze PLC Designer PLC Designer (R2-x) - Manual (Page 63)

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DMS 3.2 EN 02/2011 TD29 61
4.2.3 Sequential Function Chart (SFC)...
The Sequential Function Chart (SFC) is a graphically oriented language which makes it
possible to describe the chronological order of different actions within a program. For
this the actions are assigned to step elements and the sequence of processing is
controlled by transition elements.
Example for a network in the Sequential Function Chart
Step
A POU written in a Sequential Function Chart consists of a series of steps which are
connected with each other through directed connections (transitions).
There are two types of steps.
The simplified type consists of an action and a flag which shows if the step is active. If
the action of a step is implemented, then a small triangle appears in upper right
corner of the step.
An IEC step consists of a flag and one or more assigned actions or boolean variables.
The associated actions appear to the right of the step.