Glossary · Systems engineering and MBSE
Subsystem
In systems engineering, a subsystem is a defined part of a larger system that performs one or more functions. It has its own boundary and interfaces to the rest of the system.
- Systems engineering
- Integrated systems
In one sentence
A subsystem is a defined part of a larger system with its own functions, boundary and interfaces, often delivered by a separate supplier.
Example
In an automated palletizing line, the stretch wrapper is a subsystem with its own controller, guards and interfaces to the conveyor and the line control.
How it applies
- Integrated systems: Define each subsystem's system boundary and interfaces. Subsystem evidence is valid only within the conditions stated at those interfaces.
- Functional safety: In IEC 62061, “subsystem” has a narrower meaning: a part of a safety-related control system whose dangerous failure results in a dangerous failure of the safety function. Check which meaning a document uses.
- Evidence: Subsystem tests and certificates are inputs for the integrated system. They do not replace system-level verification.
- Technical documentation: Subsystem manuals from suppliers need to be integrated into the system documentation, with interface-specific additions.
Subsystem vs. system element
A subsystem is one kind of system element: a part that itself performs functions and has its own structure. System elements also include single components, interfaces and, in a model, requirements and evidence items.