Automated Simulation-Based Integration Testing for Multiple PLCs in a Reactor Protection System

Programmable logic controllers (PLCs) are widely used for process control and automation in safety-critical systems, such as reactor protection systems (RPS) in nuclear power plants. Industrial systems are often composed of multiple PLCs and have several interfaces with other systems. It is crucial to test PLC programs for such systems effectively. As manual integration testing is costly and time-consuming, simulation- based testing is becoming more important in validating safety- critical systems. However, simulation-based testing is limited because the simulation execution results may differ from the real PLC program execution results. This study presents the PLC synchronization method and multiple PLCs execution method for the Automated Simulation-based Integrated Testing approach (ASIT). MultiPLCTester is a test tool we developed to support ASIT and it executes test inputs with a simulation model and communicates with a PLC and compares them with execution results. Based on the synchronized test execution results, it con-ducts ASIT for target systems. We performed experiments using real industrial cases to evaluate the effectiveness and efficiency of our approach. The test suite execution time using ASIT was significantly reduced compared to the manual integration testing. When considering the test execution time and the cost of building a test bed, ASIT provides effective and efficient integrated testing for PLC testers.