FBD diagram examples.
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What an FBD diagram is.
A Function Block Diagram, or FBD, is an IEC 61131-3 PLC language that represents control logic as connected blocks. It makes signals and data dependencies visible between operations such as timers, counters, comparisons, and logic gates.
FBD is especially useful when a control function has parallel paths or when the logic is easier to review as signal flow than as contacts and coils.
- Standard
- IEC 61131-3:2013 §6.4
- Also follows
- IEC 61131-3:2013 §2.5 standard FB library
- Engine
- schematex-fbd
- Editable
- Double-click text, drag nodes
- Export
- SVG · PNG · PDF
Who uses FBD diagrams.
Describe a start/stop latch or a timed signal path before implementing it in the controller.
Review a bounded setpoint and alarm decision in a tank control function.
Trace sensor, edge, counter, and batch-complete signals in a machine sequence.
How to make an FBD diagram in three steps.
Describe it
One paragraph is enough to start.
See the drawing
Drawn by the right engine.
Say what changes
Every edit keeps a version.
Common questions
What is an FBD?
An FBD is an IEC 61131-3 PLC language that connects function blocks to show control and data flow.
How is FBD different from ladder logic?
Ladder logic resembles relay circuits, while FBD represents signals passing between functional blocks.
Which functions fit an FBD?
Boolean logic, timers, counters, comparisons, arithmetic, selection, and limit functions are common FBD elements.
What is a network in an FBD?
A network is a numbered group of related block assignments within one diagram.
Other drawings for the same work.
Create an FBD diagram.
Free account, no card. Describe the signals, blocks, and logic you need.
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