Networked Control System (NCS) based communication system Industrial Ethernet (IE) becoming very popular for automation system. The Fast Ethernet system with data rate transfer 100Mb/s is used for this project. Star topology with the hub connected to Personal Computer (PC) and the others two Programmable Logic Controller (PLC) are analysis for the real-time communications. Real-time communication for the system are very good without no disconnected between PC and PLC. Data rate transfer is Okbit/s when the communications between PC and the others two PLC are idle. When the realtime communication is on between PC and PLC A with PCL B are idle, the data rate transfer shows 57 kbit/s. Meanwhile when the PC connected to the PLC B with PLC A are idle, the data rate transfer shown from the PC are 65 kbit/s. The other situations can be taken are when the PC connected to the PLC A and PLC B, the data rate transfer for the real time communication show 115 kbit/s. The highest data rate transfer shows from this project with 115 kbit/s are below the maximum data rate transfer IMbit/s for the PC with Fast Ethernet system. © 2010 IEEE.