Abstract: 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.

Abstract: Controllers 11a, 11b that operate and execute a program programmed by a variable name and communication units 12a, 12b that communicate with other nodes connected to a network are provided. The controllers store and retain a variable table that associates the variable name with a real address that identifies an area in which data corresponding to the variable name is stored, and the communication units store and retain communication setup information that identifies a variable name that is a subject of communications with other nodes. When a system starts up, the communication units independently solve by making an inquiry to the controllers about a real address corresponding to the variable name stored in the communication setup information, and store and retain a temporary internal table that associates the variable name with the real address.

Abstract: A network system for carrying out communication between a control station and a plurality of devices connected to a network, wherein such communication includes data communication which requires real-time attributes and message communication which does not require real-time attributes, and wherein the data communication includes a first data communication in which data is transmitted from the control station to the devices and data in response to this transmission is transmitted from the devices to the control station, and a second data communication in which data is transmitted from the control station at a prescribed timing, 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; wherein 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 communicati