Glossary · Automation software engineering and architecture
Hardware-in-the-loop test
Also known as: HIL test, HIL simulation
German: Hardware-in-the-Loop-Test
In systems and software engineering, a hardware-in-the-loop (HIL) test is a test in which the real control hardware with its software is connected to a real-time simulation of the machine or process it controls, so the controller can be tested under realistic and fault conditions without the physical plant.
- Software engineering
In one sentence
A hardware-in-the-loop test connects a real controller to a real-time simulation of the machine, so it can be tested without the plant.
Example
The new crane controller is tested on a HIL rig that simulates motors, encoders and load sway, including encoder failures that would be dangerous to provoke on the real crane.
How it applies
- Engineering: HIL tests check real timing, I/O and communication of the controller, which pure software simulation cannot. They allow testing of fault cases, such as sensor failures or extreme process conditions, safely and repeatably.
- Commissioning: HIL and Virtual commissioning move testing earlier, reduce on-site commissioning time and catch integration issues before the machine exists.
- Documentation: Document the simulation model, its validity limits, the hardware and software versions tested and the test cases and results. The documentation team can also use the HIL rig to capture screenshots and verify procedures before the real machine is available.
HIL vs. software-in-the-loop
In software-in-the-loop (SIL) testing, the control software runs in a simulated or virtual controller; in HIL, it runs on the real hardware. The abbreviation SIL for software-in-the-loop must not be confused with Safety Integrity Level (SIL). A HIL test's validity depends on how well the simulation represents the real plant.