Environmental Engineering Reference
In-Depth Information
Figure 4. Classification for requirements for processes (software lifecycle)
implement the plan for verification of the changes
made. The amount and extent of evaluation of
conformity of OTS software components to these
criteria are determined by the safety class (I&C
safety class). The importance of requirements
for the use of OTS components (both developed
as special purpose and COTS-components) for
safety of the I&C systems as a whole should be
emphasized. According to existing estimates
(Kersken, 2001), the amount of OST components
in software of mature systems can reach 80-85%
of the total amount of software.
The third of the listed subgroups of require-
ments determines the need for complete and clear
description of the interfaces between the software
being examined and the operator (also known as
human-machine interface), hardware platform
and peripheral hardware (sensors, drives and so
forth) of a given I&C system, and also other I&C
devices, systems and subsystems. This descrip-
tion determines the limits of the software being
analyzed.
Restrictions for use of the operating system and
interrupts are included in requirements for I&C
software of safety class 2. If the use of the operat-
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