What is Sequential Function Chart?


What are SFC ?

SFC stands for sequential function charts.

The sequential function chart is a graphically oriented language which allows to describe the chronological order of particular actions within a program.These actions are available as separate programming objects,written in any available programming language.

In a SFC the actions are assigned to step elements and the sequence of processing is controlled by transition elements.

SFC is a high level language to describe control sequence in graphical form.

Why SFC’s are used ?

Complex logic can be difficult to write using scripting alone.

SFC streamline the creation,organization and visualization of robust logic systems.


Example of SFC

Example of SFC - Sequential Flow control


the main advantage of SFC is that even operations and investors for a plant, who dont have any idea about the automation or the language used, can see the SFC and understand the sequence of procedure.
Also when a process is running and if we visualise the SFC in the online mode, showing at what step the process right now is and what is the next immediate transition for it to go to next step. This visualization is done in almost all software of DCS and it helps in operations and other team to co ordinate with instrument technicians for trouble shooting