Function Block Diagram (FBD) vs. Continuous Function Chart (CFC)

There are two similar graphically oriented programming languages for PLCs:

Function Block Diagram (FBD) - Contains a list of networks (similar to FFLD) with each network containing a set of blocks.  The blocks are connected together by lines from the outputs to the inputs, defining the logic for the program.  The execution occurs from left to right.

Continuous Function Chart (CFC) - Contains free floating blocks.  The blocks are connected together by lines from the outputs to the inputs, defining the logic for the program.  The lines can define feedback paths for a block or blocks.  The execution order can be specified for each block.

CFC is an extension to IEC 61131-3, which removes the network and execution order restrictions found in classic FBD editors

Why choose CFC vs. FBD?  Which is better?

For KAS users, it doesn't matter!  The FBD editor in the KAS IDE is fully compliant with the CFC language.  Thus, you don't have to choose.  All the benefits of CFC are available from a single editor.

Other PLC products, started with FBD, found it too restrictive and added a new CFC editor later.  To keep backwards compatibility, they kept the FBD editor.  This can create confusion for new application developers, because they start programming with the more commonly known FBD editor, find it too restrictive, and then discover the CFC editor and have to manage programs in both editors or port FBD programs to CFC programs.