Glossary · Automation software engineering and architecture
Response time
Also known as: Response latency
German: Reaktionszeit
In software and real-time systems, response time is the time from a stimulus, such as an input event, request or task release, until the system produces the corresponding response or the task completes.
- Software engineering
In one sentence
Response time is the time from a stimulus such as an input or request until the system produces the corresponding response.
Example
The specification requires that the HMI shows an alarm within 500 ms after the controller detects the fault, measured end to end.
How it applies
- Engineering: Response time requirements need clear start and end points and conditions (load, number of connections). In real-time analysis, the worst-case response time includes execution, preemption and blocking.
- Verification: Measure response times under realistic worst-case load, not only average values; report maximum and distribution.
- Documentation: Technical data should state response times with their measurement conditions. For safety functions, the relevant figure is the Protective response time of the whole chain, which is defined and documented separately.
Response time vs. latency
The terms overlap. Latency often refers to delay in transfer or processing of one step; response time covers the complete path from stimulus to result as experienced by the user or the process.