Improvement of industrial Ethernet I/O system based on daisy chain loop

LIU Lin

(Information Engineering Department, Sichuan Electromechanical Institute of
Vocation and Technology, Panzhihua 617000, China)

Abstract: Aiming at the issues of poor opening performance and high cost in middle and long extent caused by the uniformity of protocol used in control layer and field layer of legacy I/O system, Ethernet technology was used in the communication of filed level control, which makes control layer and field layer use a unified Ethernet protocol. Based on the analysis of the difference of legacy remote I/O substation and Ethernet I/O substation, the industrial Ethernet I/O system improvement and migration process based on the daisy chain loop was investigated and the constructing method of fiberoptic main circuit and long distance hot standby fiberoptic circuit based daisy chain loop were proposed. The main loop daisy chain was contituted with the distributed I/O master module, the main loop of DRSs, the distributed I/O devices and the remote I/O network by using Quantum communication device. In the subloop, local distributed I/O devices were scanned, the distributed I/O data streamed from the subloop device was controlled by DRSs to maintain the highest priority remote I/O traffic in main circuit, to make priority control through the different levels of I/O data. The results indicate that this method not only can ensure network redundancy, but also can ensure the network efficiency and time certainty.

Key words: Ethernet; daisy chain; PLC