Network system

A network system comprising:

• a main loop in which one master node which issues a token packet specifying a transmission node, a receiving node for data communication using a data packet at regular intervals, and at least one slave node are connected in a loop;
• a first sub loop in which said master node, one sub-master node, and at least one slave node are connected in a loop;
• and
• at least one second sub loop in which said master node, at least two sub-master nodes including said sub-master node which is a component of said first sub loop, and at least one slave node are connected in a loop;
• wherein said master node comprises a first analysis execution unit which performs outputting the token packet to all the loops, analysis of the token packet, control of data transmission and data reception, and a first switch which selects one from an output of said first analysis execution unit, an input from the adjacent slave node connected in said main loop, and an input from said sub-master node which is a component of said first sub loop;
• wherein said sub-master node comprises a second analysis execution unit which performs analysis of the token packet, control of data transmission and data reception, and a second switch which selects one from an output of said second analysis execution unit, an input from the adjacent slave node connected in the self-loop, and an input from said sub-master node connected in its lower adjacent loop, and outputs it to said master or sub-master node connected in its upper adjacent loop;
• wherein said slave node comprises a third analysis execution unit which performs analysis of the token packet, control of data transmission and data reception, and a third switch which selects one from an output of said third analysis execution unit and an input from the network to said slave node;
• and
• said first switch, said second switch, and said third switch are controlled to output, transmit, and discard the token packet and the data packet.