Fault Tolerance Evaluation for WirelessHART Networks
Fault tolerance, dependability, redundancy, fault tree analysis,WirelessHART
Fault Tolerance Evaluation for WirelessHART Networks Nowadays, one of the main challenges in the context of industrial applications is related with the way like the process variables communicate. Traditionally, owing to legacy communication technologies, several applications in industrial environments are based on wired communication solutions. However, recently the industry has demonstrated interest in migrate part of the wired infrastructure to wireless in order to reduce the costs related with installation, maintenance and scalability of the applications. The challenge of this scenario is to keep the dependability requirements (reliability, integrity, maintainability, availability and safety) previously guaranteed by the wired solutions. A way to improve the dependability requirements is through redundancy. Spares devices can be used to increase the reliability and availability of applications. In this context, the WirelessHART standard appears as a candidate to be adopted as a wireless solution for industrial environments which the application focus is for process measurement and control. Nevertheless, the lack of a more elaborate study about the reliability and availability of aWirelessHART network prevents the validation of an application even during the phase of planning and design. Thus, this work proposes an architecture of redundancy (temporal, structural and hybrid) and a methodology, based on fault tree analysis technique, to evaluate the dependability of a WirelessHART network. A software tool was developed to evaluate the proposal. The tool support any topology (star, tree, cluster, mesh), different levels of redundancy, dynamic of network (changes of routes if failures occur), criticality of devices and the specification of arbitrary failure conditions. Preliminary results show that the proposal is a useful tool for the design and validation of WirelessHART applications.