IEEE 1483-2000 pdf free.IEEE Standard for Verification of Vital Functions in Processor-Based Systems Used in Rail Transit Control.
Abstract: A set of standard verification tasks for processor-based equipment used in safety-critical applications on rail and transit systems is covered. This standard also covers processes that verify the level of safety achieved in the implementation of safety-critical functions that are required to be fail-safe. Quality assurance or validation processes that affect the overall level of system safety are not covered.
Keywords: rail, safety, safety critical, software, transit, verification, vital.
The achievement of safety in railroad and transit systems is dependent upon many factors and activities. Among the required activities (for instance, those listed in MIL-STD-882C:1996) is the identification of system hazards. hazard severity, and hazard probabilities. As a result of these efforts, a portion of the system-functional requirements are identified as being critical to system safety and, as such, must be implemented fail-safely (vital functions). These vital functions must be performed as specified, and must be performed in a manner that does not increase risk in the presence of component failures (i.e., performed fail- safely). Traditional rail transit safety systems designed using only relays andlor discrete electrical or mechanical components had the performance of vital functions (with and without component failures) verified by relatively tedious, hut easily understood, means. With the introduction of integrated circuits, microprocessors. and software, the complexity of safety-critical systems has grown beyond the ability of traditional analyses as the sole means of verifying their safe operation in the event of hardware component failures andlor software errors. It is the intent of this standard to provide agreed-upon safety verification procedures and analyses that, if implemented comprehensively, will verify that identified vital functions have been implemented fail-safely with a level of safety assurance adequate to meet the stated safety goals. In the context of this standard, the safety goals are defined as the quantitative limit of the probability andlor frequency that any vital function fails to be performed safely.
Identification of the set of vital functions to be verified begins with the identification of all hazards associated with the functional and operational requirements of the system [traditionally identified by a preliminary hazard analysis (PHA) within the overall system safety program], and proceeds using analytical means to identify all vital functions at the system-functional level. Vital functions to he verified are also identified through analysis of the safety-assurance concepts employed in the system design, which impose additional requirements for fail-safe implementation. The methods used to verify such functions are safety assurance concept dependent.
Verification of system safety requires the establishment of system safety goals and proceeds using analytical means to verify that vital functions have been implemented consistent with those goals.
This standard provides a structured process and defines a set of documents that comprehensively identify the set of system functions that must be implemented fail-safely (i.e., those derived from potential hazards associated with the specific functional and operational requirements), as well as those imposed by the design concepts selected. The vital functions are then associated with hardware and software components of the system implementation. Analyses and other verilication methods are used to confirm that each of the identified functions are implemented fail-safely, and that the established safety goals are met.IEEE 1483-2000 pdf download free.