PURPOSE: To attain the relay of a token regardless of the operating state of a transmitter by providing an instruction means instructing connection/ disconnection to a network system to the transmitter, the communication right acquisition mode addressed to the own equipment and the token sending mode.

CONSTITUTION: Plural stations combining a node 2 and a piece of equipment 3 are connected to a transmission line 1 to constitute a network, in which information is sent to each other. The node 2 consists of a transmission/reception control section 4 applying data input/output control and transmission/reception control of a control frame such as token with the transmission line 1, a microprocessor 5 storing a control program controlling the entire nodes 2, an interface control section 6 synchronizing the interface with the equipment 3, a memory 7 storing tentatively a transmission data, an address setting section 8 setting a specific address to the own node and a disconnection switch 9. The network system comprising the plural stations consists of nodes 13a∼13g and various devices 19a∼19g connected to each node.