BS/EN 16590-3-2014 pdf download.Tractors and machinery for agriculture and forestry Safety-related parts of control systems Part 3: Series development, hardware and software (ISO 25119-3:2010 modified).
5.3 Prerequisites
Before beginning system design, define the safety-related function requirements, application and operation environment.
5.4 Requirements
5.4.1 Structuring safety requirements
The functional safety concept specifies the basic functioning of the safety-related system with which the safety goals are to be fulfilled. The basic allocation of functional safety requirements to the system architecture is specified by the technical safety concept in the form of technical safety requirements. This system architecture is comprised of both hardware and software.
The hardware safety requirements refine and solidify the requirements of the technical safety concept. Clause 6 describes how to specify the hardware requirements in detail.
The software safety requirements are derived from the requirements of the technical safety concept and the underlying hardware. The requirements for the software defined in Clause 7 shall be taken into account.
This clause specifies the approach to be useo en the specetication 0? the satety concept requirements during system design, thereby providing a basis for error-free system design,
5.4.2 Functional safety concept
5.4.2.1 General requirements of functional safety concept
Safety functions are normally identified during the system risk analysis, and the functional safety concept document includes the functional safety requirements for the system.
The implementation for each safety concept requirement shall consider the following.
— Feasibility
When listing functional safety requirements, attention shall be paid to the feasibility of the requirement. considering constraints, such as available technology, as well as financial and time resources. The persons in charge of implementation shall understand and accept the technical safety requirements.
— Unambiguousness
The functional safety requirements shall be formulated as precisely and unambiguously as possible.
NOTE A functional safety requirement is unambiguously formulated when it permits only one Interpretation by the
anticipated readers.
— Consistency
Functional safety requirements shall not be self-contradicting (internal consistency), nor shall they contradict other requirements (external consistency).
Analyses of the requirements and compansons between different requirements are necessary to ensure external consistency. This is a requirement management task.
— Completeness
The functional safety concept shall take all relevant norms, standards and statutory regulations into account.
The functional safety concept shall take into account all relevant safety goals derived from the risk analysis according to EN 16590-2.
The completeness of the functional safety concept increases iteratively during system design. To ensure completeness:
1) the version of the functional safety concept and the version of the relevant underlying sources shall be specified;
2) the requirements from change management (see EN 16590-4:2014, Clause 10) shall be met and, for this reason, the functional safety requirements shall be structured and formulated to provide support for a modification process;
3) the functional safety requirements shall be reviewed (see EN 16590-4:2014, Clause 6).
The functional safety concept shall consider all phases of the life cycle (including production, customer operation, servicing and decommissioning).
5.4.2.2 Specification of the functional safety concept
This clause presents the information that is required to be specified in the functional safety concept. The functional safety concept may be derived from the machine failure scenarios evaluated during a risk analysis. Each failure scenario description shall include the following:
— environmental conditions (moving on an ice covered road. up-hill, down-hill, weather, etc.):
— machine conditions (engine running, in-gear, standing still, etc.):
— resulting AgPL;
— safe state descriptions (engine stopped, valve off, transmission In park, continue function at reduced performance. etc.).
5.4.3 Technical safety concept
5.4.3.1 General requirements of technical safety concept
The technical safety concept document includes the technical safety requirements for the system.
Each technical safety concept shall be associated (e.g. by cross-reference) with higher-level safety requirements. which may be
— other technical safety requirements,
— functional safety requirements. or
— safety goals and objectives.
NOTE 1 Traceability can be greatly facilitated by the use of suitable requirement management toots.
Just as for the functional safety concept, the implementation of each technical safety concept requirement shall take account of feasibility, unambiguousness, consistency and completeness.
— Feasibility
When listing technical safety requirements, attention shall be paid to the feasibility of the requirement considering constraints, such as available technology, as well as financial and time resources. Those in charge of implementation shall understand and accept the technical safety requirements.
— Unambiguousness.BS/EN 16590-3-2014 pdf download.