PERFORMANCE COMPARISON OF SOFT PLC AND HARDWARE PLC

Sammanfattning

This thesis investigates the use of software based programmable logic controllers (soft PLCs) as an alternative to traditional hardware PLCs in industrial automation. As automationsystems become software centric, the ability to execute logic on general purpose hardwaregives opportunities for flexibility, scalability and the ability to run control logic independentlyof dedicated hardware. This introduces challenges related to real-time performance,determinism, and deployment in existing industrial environments. To explore these aspects, asoft PLC was implemented on a Raspberry Pi and setup into an existing automation system. Atest setup was constructed to measure system timing behavior including cycle timecharacteristics and end-to-end response time when interacting with distributed I/O usingindustrial communication protocols. Measurements were performed on both the originalhardware PLC based setup and the soft PLC based setup to allow comparison of behavior.The results demonstrate that the soft PLC solution can achieve communication comparable tothe hardware PLC while maintaining acceptable latency and jitter values. This indicates thatthe soft PLC could be seen as a viable alternative in scenarios where flexibility and scalabilityare required, while hardware PLCs remain suitable in many industrial deployments. Thesefindings contribute valuable insights for future research.