Industrial Engineer · phase 3 of 16
Function Block Diagram (FBD)
IEC 61131-3 graphical language that connects functions and function blocks with signal lines.
The Explain card
- Plain English
- FBD draws logic as boxes wired together with signal lines. Each box is a function or a function block, and the lines carry values from one output to the next input.
- Example
- A temperature input feeds a scaling block, which feeds a PID block, which feeds an analog output block. You read the loop left to right like a flow chart.
- Why it matters
- Continuous signal processing that is a mess of parallel rungs in ladder is one clean diagram in FBD. It is the natural home for loops, math and drive control, and it shows data flow rather than sequence.
- Hook
- Ladder shows what switches, FBD shows what flows.
Where it sits in the deck
Phase 3: PLC Program Organization and Execution
How the logic is arranged and how the scan actually runs it, which is the difference between code that works and code that works every time.
