Definition:
The Safety Requirements Specification (SRS) is the detailed document that captures all functional and integrity requirements for the entire Safety Instrumented System (SIS) each Safety Instrumented Function (SIF). It is often the most important deliverable the engineering team will produce. A LOT of information goes into this document. At times it is so complex, it is split. One common way is a SRS by title is released, then SIF specific documents are then released.
Another way to think of this is that the SRS is the document that documents numerous decisions on HOW the SIS will be designed.
Key Points:
- Forms the basis for system design and validation.
- Should be updated throughout the lifecycle.
- The requirements are so many for this document it may get split it into multiple documents. Such as a document per SIF and an overall SIS wide SRS.
Example:
SRS includes trip points, response times, proof test intervals, and SIL targets.
See also: SIS, SIF, Safety Lifecycle
Cited Source:
- IEC 61511-1:2016, Clause 10.3.