Formal Specification and Verification of PLC for Certification

KNICS (Korea Nuclear Instrumentation and Control System) is a national promoted project to develop a safety-critical level embedded system for nuclear plant protection system. PLC(Programmable Logic Controller) is a typical embedded system to instrument and control plant system, and KNICS has been developing a PLC for controlling a reactor of nuclear power plant system. The PLC micro-kernel is a safety-critical software that should be certified by KINS (Korea Institute of Nuclear Safety), the certification organization in Korea. In this paper, we present our experience on developing micro-kernel in PLC based on formal specification and formal verification. Using formal methods, we gain correctness of the target software and when the project ends, we will apply a certification to KINS.