Industrial communication networks play a crucial role in ensuring the efficiency and reliability of automated systems. This study presents a practical and simulation-based approach to evaluate the performance of the MODBUS-RTU protocol, one of the most widely adopted industrial protocols. A physical circuit was implemented consisting of two interconnected units— a Master and a Slave—designed to measure key performance parameters such as frame delay and frame rate. In parallel, a simulation model was developed using the OPNET network simulator to replicate the same communication scenario and validate its accuracy. The results showed strong agreement between the real-world measurements and the simulation outcomes, with an error margin not exceeding 0.25%. This confirms both the high performance of the MODBUS-RTU protocol and the reliability of the OPNET simulator for modeling industrial networks. The study further highlights the impact of various factors on network performance, paving the way for future improvements in Quality of Service (QoS) through both experimental and simulation-based methods.