Hitachi, Ltd.

Shouji Yoshida

Tsutomu Yamada

Tatsuya Maruyama

Mitsuyasu Kido

Kazuhisa Takami

Chikashi Komatsu

There is provided a communication control device including: a real-time communication status extraction unit that acquires a communication timing of real-time data; a dynamic fragment size determination unit that acquires a fragment size of sending data which can be sent until the communication timing acquired by the real-time communication status extraction unit; a fragment processing unit that fragments non-real-time data to have at least a fragment size which is equal to or less than the fragment size acquired by the dynamic fragment size determination unit; and a communication unit that sends the non-real-time data, which is fragmented by the fragment processing unit, before the communication timing of the real-time data.

Communication control device with dynamic fragmenting of non-real-time data

An object of the present invention is to provide a network system or the like in which the construction cost of a network for a plurality of control systems is suppressed which is excellent in resistance to a network failure. In order to solve the problems, according to the present invention, there is provided a network system including a plurality of communication devices that are disposed in a plurality of bases, and are grouped into predetermined control systems for each of the devices which transmit and receive packets to and from each other so as to monitor or control target equipment, and a plurality of relay devices each of which includes a plurality of communication ports and transmits a packet transmitted by the communication device to another communication device, in which a plurality of communication devices disposed in each base are connected in parallel between the two relay devices, the relay devices disposed in different bases are connected to each other in a ring shape via a network, and a plurality of communication devices disposed in at least one base include communication devices belonging to different control systems.

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Tokyo, Japan

Shouji Yoshida