Building on the base of STEP 7, the S7-Graph package adds the IEC 61131-3 standard sequential function chart (SFC) language to your toolbox. SFC is an ideal language for configuring sequential operations. An intuitive graphical step-transition approach is used, with your sequential process divided into defined steps with clear transitions between steps. Each step has a defined action which either directly drives output devices or interacts with existing ladder logic or function blocks for device control. SFC provides built-in interlocking between steps since all transition conditions must be met to advance in the sequence. SFCs can be nested (subsequences) for more sophisticated sequential control applications. S7-Graph is tightly integrated with the HMI packages SIMATIC WinCC and WinCC Flexible, providing everything from display of process diagnostic messages to online display of sequences in WinCC.