Glossary · Distributed automation and IEC 61499
Execution control chart (ECC)
Also known as: ECC
German: Ausführungssteuerungsdiagramm (ECC)
In IEC 61499, the execution control chart (ECC) is the state machine of a basic function block, consisting of EC states, EC transitions with event and Boolean conditions, and EC actions that invoke algorithms and emit output events.
- IEC 61499
- Standards
In one sentence
The ECC is the state machine of an IEC 61499 basic function block that runs algorithms and emits events in response to input events.
Example
The ECC of a motor block has the states START, IDLE, RUNNING and FAULT; the event input RUN moves it from IDLE to RUNNING, where it executes the algorithm StartMotor.
How it applies
- Engineering: Every basic function block has exactly one ECC with an initial state. Transitions are evaluated when an event arrives; a transition condition combines an event input with an optional Boolean guard. Entering a state executes its actions in order.
- Design: Keep ECCs small and readable: a handful of states with clear names. Complex behavior is better split into several blocks.
- Testing: ECCs support systematic tests: every state, transition and action can be covered by event sequences, similar to testing any Finite-state machine (FSM).
- Documentation: ECC diagrams can be included directly in block reference documentation. Add a table of transitions (from, to, event, guard) for readers who print or translate the documentation.
ECC vs. SFC
The ECC controls one basic function block and reacts to events. Sequential function chart (SFC) structures larger program sequences in IEC 61131-3 and is evaluated cyclically. Both are state-based but differ in scope and execution model.