Dual PLC-based HMI control and monitoring of siemens VFDs using profibus and profinet networks

Abstract

This project presents the design and implementation of an advanced industrial automation system for controlling Siemens MICROMASTER 420 Variable Frequency Drives (VFDs) using a programmable logic controller (PLC)-based architecture. The central control unit is a Siemens S7-1500 PLC programmed with TIA Portal V15.1, which manages communications with an S7-300 PLC via a PROFINET network, where the S7-1500 operates as the server and the S7-300 as the client. In parallel, the S7-300 PLC functions as a PROFIBUS master to control three VFDs, each of which governs an induction motor. The VFDs act as DP slaves, receiving commands and returning operational data such as faults, alarms, and load conditions. An integrated Human-Machine Interface (HMI) replaces the conventional Basic Operator Panel, enabling users to monitor and control system variables such as motor speed, direction, and operating status. The HMI also supports real-time diagnostics and control functionalities for improved system responsiveness and user accessibility. Data exchange between PLCs is achieved through the implementation of the PUT/GET communication blocks in STEP 7, while SFC 14 and SFC 15 functions facilitate PROFIBUS-based communication with the VFDs. The proposed system demonstrates a flexible and scalable solution for modern industrial motor control, combining high-performance communication protocols with intuitive user interaction.