Glossary · Automation software engineering and architecture
Software-in-the-loop test
Also known as: SIL test, SiL test
German: Software-in-the-Loop-Test
In control software development, a software-in-the-loop test runs the compiled control software on a host computer against a simulation of the controlled system, without the target hardware, to verify its behavior early.
- Software engineering
In one sentence
A software-in-the-loop test runs control software on a PC against a simulated plant, without target hardware, to verify it early.
Example
Before the controller hardware is delivered, the team runs the PLC code in a software-in-the-loop setup against a simulation model of the palletizer.
How it applies
- Engineering: SIL tests find logic errors early and can be automated in the Test pipeline. They do not cover target timing, hardware interfaces or I/O behavior.
- Verification: SIL results count as verification evidence only for what the simulation represents; the fidelity and limits of the plant model must be stated.
- Documentation: Test reports should name the simulation model version and assumptions. Virtual commissioning setups can also produce screenshots and sequences for the documentation team before the real machine exists.
Software-in-the-loop vs. SIL
The abbreviation SIL also stands for Safety Integrity Level in functional safety. In documentation, write out software-in-the-loop to avoid confusion with Safety Integrity Level (SIL).