Function Block Diagram (FBD)

A function block diagram is a data flow between constant expressions or variables and operations represented by rectangular blocks.

Example

Data Flow

  • The data flow represents values of any data type.
    • All connections must be from input and outputs points having the same data type.
  • With a Boolean connection, use a connection link terminated by a small circle.

  • The data flow must be understood from the left to the right and from the top to the bottom.
    • It is possible to use labels and jumps to change the default data flow execution.

FFLD Symbols

FFLD symbols can also be entered in FBD diagrams and linked to FBD objects.

  • See these sections for information about components of the FFLD language:
  • Special vertical lines are available in FBD language for representing the merging of FFLD parallel lines.
    • Such vertical lines represent a OR operation between the connected inputs.

Figure 1: Example: OR Vertical Line used in an FBD Diagram

See Also