Modicon M340 Plc Page 4-6 Services

4/6 Presentation Technical information Ethernet network Infrastructure Presentation The ConneXium Industrial Ethernet offer comprises a complete family of products and tools (including the ConneXium Network Manager (CNM) software tool) required to build the infrastructure of an Industrial Ethernet network. The following pages provide information on network design and component selection. Office Ethernet versus Industrial Ethernet There are three main areas of differentiation between Ethernet applications in an office environment and those in an industrial environment: b Environment b Layout (not physical layer specification) b Performance Contrary to the office environment and even though ISO/IEC is working on it, as yet there are no clearly defined specifications for Ethernet devices intended for industrial applications. The specifications of what it is called Industrial Ethernet are defined by different agencies or entities based upon its nature and what the automation market has traditionally used. The environmental specifications of Industrial Ethernet devices are defined by the traditional agencies that define the environmental specifications for standard industrial devices (UL, CSA, e , etc.). IEEE 802.3 defines the physical layer specifications of the Ethernet network (types of connector, distance between devices, number of devices, etc.) while standard 11801 (similar to TIAEIA 568B and CENELEC EN 50173) provides layout guidelines for installers. The performance specifications are currently being drawn up by ISO/IEC. Ethernet 802.3 principles The Ethernet 802.3 Link Layer is based on a collision detection mechanism (CSMA CD) whereby every node whose information has collided on the network detects the collision and re-sends the information. The process of re-sending information causes delays in its propagation and could affect the application. A collision domain is a group of Ethernet end devices interconnected by hubs or repeaters (devices that receive information and send it out to all their other ports, no matter where the destination device is connected). This means that all devices will be affected by collisions. With full duplex switches (devices that receive information and only send it out through the port to which the destination device is connected), there are no collision domains. Therefore, for industrial automation applications it is highly advisable to use full duplex switches to interconnect devices. This will help eliminate collision domains. 2 1 3 4 5 6 7 8 9 10 2 1 3 4 5 6 7 8 9 10

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