Glossary · Data, timing and communication
Event-driven communication
Also known as: eventing, event-based communication
In systems engineering, event-driven communication is a communication pattern in which data is sent when a defined event or state change occurs, rather than at fixed intervals or on request.
- Data and interfaces
- Integrated systems
In one sentence
Event-driven communication sends data only when something changes; it is efficient, but silence must never be read as “nothing happened.”
Example
The PLC of a conveyor publishes a message when a jam sensor trips, and the line controller stops the upstream conveyors on receipt instead of polling the sensor every 100 ms.
How it applies
- Integrated systems: Define exactly which events are sent, their payload, timestamp and ordering, and whether delivery is guaranteed. Lost and duplicated events are typical failure modes, so receivers should handle duplicates safely.
- Functional safety: The absence of events is ambiguous: no change, or a lost connection? Combine events with heartbeat messages or a timeout so that a silent failure is detected.
- Technical documentation: Event lists (name, trigger, meaning) are part of the interface documentation and must stay aligned with the state model.
Event-driven communication vs. polling
With polling, the receiver asks for the current value at intervals; with event-driven communication, the sender reports changes. Polling creates predictable load and detects dead links quickly. Events reduce traffic and delay when changes are rare. Many systems combine both.