PLC Diagnosis and Monitoring System

Programmable Logic Controllers (PLCs) are essential to industrial automation, where real-time diagnostics are critical in preventing faults and ensuring operational resilience. This paper presents an IoT-based PLC Diagnosis System that monitors critical parameters voltage, current, temperature, humidity, and vibration using an ESP32 microcontroller, various sensors, and an I2C LCD. The system transmits sensor data over MQTT and visualizes this in a Node-RED dashboard; alerts trigger LEDs and buzzer with threshold exceedance. With usercontrolled display modes, the segmented gauge allows continuous PLC diagnostics. The remote access and data storage that it allows through MongoDB integration are useful for timely interventions. Experimental results confirm the system's efficiency and affordability in real-time PLC diagnostics of industrial applications.