FBD

Function Block Diagram

A graphical language for programming of PLC's (Programmable Logic Controllers). Part of IEC 1131. In FBD, program elements appear as blocks connected together like a circuit. The blocks may be programmed in another IEC 1131 language, LD, IL, or ST. FBD is most useful in applications with a large amount of information flow between components, such as process control. See also SFC.