Fault tolerant remote terminal units (RTUs) in SCADA systems

A SCADA system uses a number of remote terminal units (RTUs) for collecting field data and sending it back to a master station, via a communication system. The master station displays the acquired data and allows the operator to perform remote control tasks. An RTU is a microprocessor based standalone data acquisition control unit. As the RTUs work in harsh environment, the processor inside the RTU is susceptible to random faults. If the processor fails, the equipment or process being monitored by it will become inaccessible. This paper proposes a fault tolerant scheme to untangle the RTU´s failure issue. According to the scheme, every RTU will have at least two processing elements. In case of either processor´s failure, the surviving processor will take over the tasks of the failed processor to perform its tasks. With this approach, an RTU remain functional despite the failure of the processor inside the RTU. Reliability and Availability modeling of the proposed fault tolerant scheme have presented.