Glossary · Requirements and interfaces
Interface specification
German: Schnittstellenspezifikation
In systems engineering, an interface specification is a controlled definition of normal behavior, fault behavior, timing, data meaning, limits and responsibilities at an interface. It is detailed enough to design and test both sides against it.
- Data and interfaces
- Systems engineering
- Verification
In one sentence
An interface specification defines normal and fault behavior, timing, data meaning and limits at an interface so both sides can be built and tested.
Example
The interface specification for a safety laser scanner connected to an AGV controller defines the field switching signals, the maximum switching time, the reaction to a lost connection and the units of the speed input.
How it applies
- Fault behavior: Specify what happens on missing, late, invalid or implausible data, not only the normal case. Timeouts and fault reactions are part of the specification.
- Data meaning: State the engineering unit, range and meaning of every value. Refer to the data model version.
- Machine safety: For safety-relevant signals, include the timing budget (for example maximum latency) that the safety function calculation relies on.
- Evidence: Derive interface tests directly from the specification, including fault injection for the fault cases.
Interface specification vs. ICD
The interface specification is the technical definition. The interface control document is the agreed and controlled document that fixes the interface between parties, including organizational requirements, and may reference the specification.