System-software interfaces for safety-related digital I&C systems

The purpose of this paper is to discuss a structured software development process based on a graphical method which relates functional requirements and software specifications to the detailed software design and implementation. This paper presents a systematic logic-based method. This approach may be used to model the functional specifications of digital instrumentation and control systems used for safety purposes. This graphical representation of functional requirements is depicted through a multilevel hierarchical decomposition technique which allows one to (i) show functional interrelations between system and software (ii) map to follow functional information from the system level to the software implementation (requirement, design, code), (iii) address incomplete, inconsistent, and ambiguous requirements.