Programmable Logic Controllers in the Context of Industry 4.0

Programmable logic controllers (PLCs) are an established platform, widely used throughout industrial automation but poorly understood among researchers. This article gives overview of the state practice, explaining why this settled technology persists industry and presenting a critical analysis strengths weaknesses dominant programming styles for today's PLC-based systems. We describe software execution patterns that standardized loosely in IEC 61131-3. identify opportunities improvements would enable increasingly complex applications while strengthening safety reliability. Specifically, we propose deterministic, distributed models embrace explicit timing, event-triggered computation, improved security.