Function Block Diagram (FBD)

Function Block Diagram

FBD is the graphical “boxes and wires” language. Each function block instance is drawn as a box with named input pins on the left side and named output pins on the right; signals are wires between pins. The visual closely matches the block diagrams common in control engineering, which is why FBD is the language of choice for control loops, filter chains and signal-conditioning networks.

ForgeIEC exposes FBD via the same graph editor as LD; the persisted form is PLCopen XML.

Sub-pages

• Elements — blocks, wires, in/out variable elements, execution-order rules.