Functional block diagram

A functional block diagram, in systems engineering and software engineering, is a block diagram that describes the functions and interrelationships of a system.

They became a necessity in complex systems design to "understand thoroughly from exterior design the operation of the present system and the relationship of each of the parts to the whole.

"[3] Many specific types of functional block diagrams have emerged.

Many software development methodologies are built with specific functional block diagram techniques.

An example from the field of industrial computing is the Function Block Diagram (FBD), a graphical language for the development of software applications for programmable logic controllers.