Glossary · Systems engineering and MBSE
System boundary
Also known as: Boundary
German: Systemgrenze
In systems engineering, a system boundary is the defined limit that identifies which components, interfaces, operating assumptions and responsibilities belong to the assessed system. Everything outside it is treated as environment or as a separate system with its own responsibilities.
- Systems engineering
- Integrated systems
- German source term
In one sentence
Why the system boundary decides what a risk assessment, a test campaign and a manual actually cover, and where interfaces to other systems begin.
Example
For a robot cell fed by a conveyor, the integrator draws the system boundary at the conveyor transfer point and records the conveyor's stop signal as an interface rather than as part of the cell.
How it applies
- Machine safety: The boundary sets the scope of the risk assessment. In ISO 12100 terms it is closely tied to the machine limits: use, space and time limits describe the same scope from the machine's point of view.
- Integrated systems: Every flow of energy, material, data or commands that crosses the boundary is an interface. If an interface is not listed, nobody has assessed it.
- Technical documentation: State the boundary explicitly in the technical file and the operating manual, including which neighboring equipment is excluded and who is responsible for it.
- Evidence: When the boundary moves (a new feeder, a shared guard), tests and claims that relied on the old boundary have to be reviewed.
System boundary vs. machine limits
Machine limits describe the intended use, space and time envelope of one machine. The system boundary decides which elements are inside the assessed system at all. In an integrated system the boundary can include several machines, each with its own limits.