Hellop;
SFC (also known as GRAFCET) is a design tool for automation control (it can be used to organize Ladder logic, or it can be used as a programming tool).
Break down your process in distinct and logically seperate steps (actions). Determine the logic that will enable each step at its own time (transitions). Setup a structure that will allow logic to flow from one step to another according to strict rules of evolution (only one transition valid in a sequence at any one time; only one step active, , unless the evolution requires parallel processing of logic [AND evolution]; etc...)
It is a very powerfull tool for sequential process design (conveyor lines, packaging lines, etc...)
The following diagram is extracted from a process we are controlling in PCS7, with the SFC editor.
Hope this helps,
Daniel Chartier