Runtime Verification of A PLC System: An Industrial Case Study

Abstract: The term verification can mean different things to different people based on their background and the context of research. Comparably the term runtime might bring about similar disarray with lesser confusion. Whilst a software application executes on a system, there are libraries and codes that facilitates the execution of that binary, these processes and libraries make up the runtime environment, and verification in this context refers to the concrete techniques that verify a run and checks if it satisfies or defies the specified requirements. This study is specifically concerned with runtime verification systems, and how to make use of them in a limited-resource environment such as embedded systems or Programmable Logic Controller (PLC). It is of utmost importance to validate the conformance of a system, specially those in automotive and transportation industry. Vehicles such as trains are responsible to transport millions of people everyday which makes safety and reliability of the system the most prime component of bunch. Many manufacturers employs state of the art technologies and processes to endure the safety of the final product. Since most of the parts in vehicles (including trains) are computer controlled, the system (OS, application, control system, etc.) should undergo proper and comprehensive tests to single out even the smallest anomalies and misbehaviour. While traditional software testing can detect most of the anomalies, runtime verification can be used as a complementary method to passively monitor the running system and point out those behaviours and malfunctioning that are otherwise close to impossible to be caught. This thesis investigates runtime verification in train manufacturing, and propose a structured, contemporary process and system to monitor the train control system for conformance. Furthermore several methods of formal specification to be used for declaration of specification were explored and a suitable choice for this case study was suggested, in addition a proof of concept tool to demonstrate the entire process is developed as well.