The article provides a comparative analysis of four communication protocols between Omron PLC and PC for their use in real-time control of an industrial robot. The need for real-time communication appears when the robot control system is located on an external PC. The subject of the study is the FINS, CIP, UDP, and OPC protocols. The physical medium for data transmission is Fast Ethernet 100 Mbit/s. The average time characteristics of reading, writing, and write/read cycle for each protocol are given. The evaluation of the applicability of protocols for real-time robot control and the convenience of their use is also given.