Patent attributes
A network system for carrying out communication between a control station and a plurality of devices connected to a network. The communication includes data communication which requires real-time attributes and message communication which does not require real-time attributes. The data communication includes a first data communication, and a second data communication. The system includes a plurality of transmission queues for temporarily storing transmission data provided in the control station, wherein one of the queues holds transmission data for the second communication. After the first data communication is carried out in accordance with a predetermined cycle time, an appropriate switching between the message communication and the second communication is carried out in the remaining time of the cycle time to complete one cycle, whereafter the cycle is repeatedly carried out.