Software Qualification Approach for Safety-Critical Software of the Embedded System

Programmable Logic Controller (PLC) is applied to a control system as major components in industrial functional safety facilities. This paper describes the safety-critical software qualification approach which corresponds to the software verification and validation, software safety analysis, software quality assurance and software configuration management etc. Major qualification activities for safety-critical software are a technical evaluation, licensing suitability evaluation, inspection and traceability analysis, formal verification, software safety analysis, software quality assurance and its software configuration management etc. First, the technology evaluation performs a technical review which was based on engineering decision-making by verifiers. Second, the licensing suitability evaluation was performed according to the Code & Standard criteria by analyzing the designed outputs based on the functional characteristics and process characteristics defined in the verification and validation guidelines. Third, the inspection and traceability analysis covers the correctness, consistency, completeness, properties of the inputs and outputs, behavioral entities, interfaces, etc. with a three-folded checklist topology. Fourth, a formal verification perform for the statechart based on the Software Requirement Specification (SRS) and the Software Design Specification (SDS) by a Graphical Back Animation (GBA) and a simulation. Fifth, the software safety analysis use the HAZard Operability (HAZOP) method and it analyze the Failure Mode Effect Analysis (FMEA). Finally, a software configuration management under the software quality assurance estimate for the software documents and the source codes by using Software Configuration Management tool. We believe that we achieve the functionality, performance, reliability and safety that are the software qualification objective goals of the embedded system.