In this article, we introduce an innovative solution for improving human–computer interaction (HCI) in programmable logic controllers (PLCs). By integrating Python, web APIs, sockets, and the pymodbus library, we've developed a web-based Human–Machine Interface (HMI) tailored for industrial controllers. The system employs web sockets for real-time connectivity between the HMI and PLC, enabling swift data exchange. Additionally, it incorporates REST web services supporting JSON messages, enhancing communication efficiency. The approach is compatible with various SCADA network protocols, providing a versatile solution for robust controller-HMI connections. The primary goal is to offer a cost-effective and customizable technology, promoting the adoption of Industry 4.0 principles among Small and Medium-sized Enterprises (SMEs). Illustrated through a case study in a medium-sized beverage bottling plant, the solution automates Cleaning in Place (CIP) processes. It provides enhanced reliability and security, addressing critical aspects of industrial operations. Unlike desktop-based SCADA software, our web-based solution transforms a PC into a server. It allows platform-independent access to any number of users via browsers on devices like laptops, Android mobiles, and tablets. The technology's distinctive feature lies in its ability to facilitate creative and multi-layered monitoring systems, leveraging the Modbus communication protocol in PLCs. In summary, this article presents a comprehensive HCI approach in PLCs, integrating Python, web APIs, sockets, and pymodbus. The solution not only tackles real-time data exchange challenges but also emerges as a cost-effective, versatile tool applicable to Industry 4.0 adoption, cybersecurity testing, high-speed simulations, and animated visualizations of mechatronic systems. Its potential to reshape digitization services by enhancing efficiency, flexibility, and accessibility for SMEs is evident.