Engineering SCADA Products for Use in Safety-Related Systems

Abstract

Supervisory Control and Data Acquisition (SCADA) systems are a class of control system used in a variety of application domains. Although SCADA systems are rarely relied on to provide the sole mitigation against high-risk hazards, they are frequently used to contribute to the management of hazardous situations, or to implement partial defences. As such, in some applications, SCADA systems are safety-related systems (as opposed to safety-critical systems). In determining the safety integrity requirements of a SCADA system, one must consider the environment in which the system is to be deployed, taking into account the availability of other hazard defence mechanisms and considering the proposed operational procedures . In this sense, the safety integrity requirements are generally not known until a safety analysis of a specific system in its target environment is performed. On the other hand, there is a growing demand for the use of standard, COTS, SCADA products that are combined to synthesize systems. This paper discusses the issues involved in engineering a base SCADA product for use in a diverse range of systems, both safety-related and non-safety-related. In particular, we address the issue of how to provide a base level of product assurance that can be used, if it ultimately proves necessary, to support system safety cases.