Glossary · Automation fundamentals, platforms and components
Real-time system
Also known as: Real-time computing
German: Echtzeitsystem
In automation and computing, a real-time system is a system whose correct behavior depends not only on the logical result of a computation but also on the time at which the result is produced. Hard real-time systems must meet every deadline; soft real-time systems tolerate occasional misses with degraded quality.
- Automation components
In one sentence
A real-time system is correct only if it delivers results within defined deadlines; hard real-time allows no misses, soft real-time some.
Example
A motion controller must compute new position setpoints every 1 ms; a single late cycle can cause a following error and stop the axis.
How it applies
- Engineering: Controllers, drives and real-time networks guarantee bounded Latency and Jitter. Designers assign priorities and cycle times to each Task and check that worst-case execution time fits.
- Commissioning: Measure actual cycle times and overruns under full load, not only on an idle system.
- Documentation: State timing requirements as numbers (cycle time, maximum response time, allowed jitter) in specifications and interface descriptions. "Real-time" alone is ambiguous: a web dashboard and a servo loop both use the word with very different meanings.
Real-time vs. fast
Real-time means predictable, not necessarily fast. A system that answers in 10 ms every time is real-time; one that usually answers in 1 ms but sometimes takes 200 ms is not, even though it is faster on average.