Function Block Diagram

Definition

A function block diagram (FBD) is a graphical representation used to describe the behavior of programmable logic controllers (PLCs) by illustrating the functions and the flow of data between them. This method is designed to simplify complex control systems, allowing users to visualize and organize the logic of processes clearly. Function block diagrams employ blocks to represent functions and lines to show connections, which facilitates easier programming and troubleshooting of automation systems.

5 Must Know Facts For Your Next Test

1. Function block diagrams are part of the IEC 61131-3 standard, which defines programming languages for PLCs.
2. Each block in an FBD can represent different types of functions, such as logical operations, arithmetic calculations, or timers.
3. FBDs allow for modular programming, where function blocks can be reused across different programs or projects.
4. The visual nature of FBDs makes them easier for engineers and technicians to understand complex automation processes at a glance.
5. Function block diagrams can be integrated with other PLC programming languages, allowing for hybrid approaches that leverage the strengths of multiple styles.

Review Questions

• How do function block diagrams enhance the programming experience for PLCs compared to traditional methods?
  • Function block diagrams enhance the programming experience for PLCs by providing a visual representation of control logic that simplifies understanding and troubleshooting. Unlike traditional text-based programming methods, FBDs allow users to see how functions connect and interact with each other at a glance. This clarity helps engineers quickly identify issues and optimize their programs by rearranging blocks without extensive reprogramming.
• In what ways do function block diagrams support modular programming practices in automation systems?
  • Function block diagrams support modular programming practices by allowing users to create reusable function blocks that can be implemented in multiple projects. This modular approach streamlines the development process since established blocks can be incorporated into new designs without starting from scratch. By promoting code reusability and organization, FBDs facilitate better collaboration among teams working on complex automation systems.
• Evaluate the significance of the IEC 61131-3 standard in the context of function block diagrams and their application in industrial automation.
  • The IEC 61131-3 standard is significant as it establishes a common framework for various programming languages used in industrial automation, including function block diagrams. This standardization ensures interoperability among different PLC manufacturers and systems, making it easier for engineers to work across diverse platforms. By adhering to this standard, function block diagrams become a universally recognized tool, enhancing communication and efficiency within the field of industrial automation while simplifying training for new technicians entering the industry.

Related terms

Programmable Logic Controller (PLC): An industrial digital computer used for automation of electromechanical processes, such as control systems for machinery or factory assembly lines.

Ladder Logic: A programming language that represents a control circuit diagram, commonly used in PLC programming that resembles electrical relay logic diagrams.

Control System: A system designed to manage, command, direct, or regulate the behavior of other devices or systems using control loops.