designing an ethernet system

8/2/2019 Designing an EtherNet System

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Copyright © 2009 Rockwell Automation, Inc. All rights reserved.

Designing an

EtherNet/IP Cable

System



Copyright © 2008 Rockwell Automation, Inc. All rights reserved. 2

Objectives

• Identify an environment class

• Select EtherNet/IP network hardware components

• Select cable system components• Select a network topology

• Select a wiring scheme

• Identify network and operational requirements




EtherNet/IP Network Overview

• “Defacto" standard for information networks

• Wide range of devices from many different vendors• Used in office networks and on plant floors

• Data easily exchanged between the plant floor and office networks

Ethernet Network:





EtherNet/IP (Industrial Protocol) Network:

• Enables interconnectivity with other networks that use CIP at the

application layer





CIP (Common Industrial Protocol):

• Enables I/O control over an EtherNet/IP network

• Bridges EtherNet/IP devices with devices on networks such asControlNet and DeviceNet that also use CIP at the application layer

Tip: Standard EtherNet/IP and Ethernet CIP safety modules can

communicate on the same network.





OSI (Open System Interconnection) Model:

• Consists of seven layers

• Each layer uses services of layer below it and supplies higher levelservices to layer above it to communicate





IPNetwork

TCP, UDPTransport

Session

PresentationCIP, CSP, HTTP

FTP,TELNET

Application

ProtocolLayer

Correlating the seven layers with common protocols:

10/100baseT,

Transceiver, etc.Physical

EthernetData Link





Packet:

• Contains address(es) of destination device(s) in addition to data




Environment Class

ODVA’s Mechanical Ingress Climatic and EMC (MICE) concept:

Mechanical Ingress Climatic Chemical EMC

(Electromagnetic)Shock Liquid particles Temperature Electrostatic

discharge

Vibration Humidity Radiated and

conducted radiofrequency

Crush Contaminants (dry

and liquid)

Transients

Impact Solar radiation Magnetic fields




Environment Class

The MICE concept defines three distinct area or classifications:

• MICE 1

• MICE 2• MICE 3

Tip: For further detailed information on the MICE concept, see theODVA’s EtherNet/IP Media Planning and Installation manual at

http://www.odva.org.




EtherNet / IP Network Hardware Components

• Ethernet Backbone

• Bridge





Only messages between nodeson different segments pass

through the bridge.

Messages betweennodes on segment A stay

on segment A.

Messages betweennodes on segment B stay

on segment B.

Segment A

00BC03 . . .

00AE44 . . .

Bridge

Segment A Segment B





• Gateway

• Transceivers





Hub:

Hubs do not selectively route

packets of information tospecific devices.

A message coming in

one port will bebroadcast out every

other port.

• Serves as multi-port repeater and central connection point on star topology

• Consumes more network bandwidth than a switch• Decreases network performance





Router:

When a message isreceived at the router, itrefers to its routing table

to determine whichsegment to route the

message to.





Switch:

Incomingmessages are only

transmitted todesired node.

Switches selectivelyroute packets of

information to specificdevices.




Switch Select ion

Switches must be chosen based on their suitability to the environment.

Two types of switches:• Unmanaged

• Managed




Switch Select ion

Benefits of a managed switch:

• Monitor the performance of the network

• Set up broadcast domains

• Run single computers on managed switch ports




Switch Select ion

• Full-Duplex Operation

• IGMP (Internet Group Management Protocol)

• IGMP Snooping




Switch Select ion

Port-Mirroring:

• Uses it as a diagnostic tool or debugging feature, especially when

fending off an attack against the network

• Is able to keep close track of and alter switch performance

• Can manage it locally or remotely

Network administrator:




Switch Select ion

• Wire-Speed Switching Fabric

• Simple Network Management Protocol (SNMP)




Switch Select ion

VLAN (Virtual (or logical) Local Area Network):

Accounting Engineering

Production Human Resources

• Can change or add workstations

• Can manage load balancing and bandwidth allocation more easily thanwith a physical picture of the LAN:




Switch Select ion

Controller 1 PC Controller 2

VLAN 1 VLAN 2

I/O I/O I/O I/O

I/O

1 3 2

4 5 6 7 8

With VLANs, a switch can be configured to share two isolated networks

without the traffic from one network burdening the other.




Switch Select ion

Web Server:

• Computers host web sites on Internet by means of web server program.

• Web servers often part of larger package of Internet- and intranet-relatedprograms for:

– Serving email

– Downloading requests for FTP files

– Building and publishing web pages.




Cable System Components

Two types of EtherNet/IP cabling:

• Copper

• Fiber optic




Copper Cabling

Two types of copper cabling:

• Coaxial

• Twisted-Pair




Copper Cabling

Shielded cables should not be used in

environments that are likely to have

ground offsets due to electrical storms or

poorly grounded buildings/installations.

Two types of copper cabling: – Shielded, balanced twisted-pair (STP/ScTP)

– Unshielded twisted pair (UTP)




Copper Cabling

Immunity to noise is influenced by the following cable design factors:

• Cabling category used:

– CAT 5E

– CAT 6

– CAT 6E

• Measurement of balance for cables:

– Transverse Conversion Loss (TCL)

– Equal Level Transverse Conversion Transfer Loss (ELTCTL)

• Coupling attenuation of shielded cables




Copper Cabling

Immunity to noise is influenced by the following cable design factors:

• Measurement of cable return loss

• Measurement of wire gauge at high temperatures• Length of the channel

• Use of shield/unshielded cables

• Grounding and bonding of the building and equipment




Two-Pair Cabl ing vs Four -Pair Cabl ing

Two-pair cable applications:

• Machine applications

• Flexible applications• High flexible applications

• Elevated noise applications

Four-pair cable applications:

• Voice, video and data

• Future increased traffic




Fiber Opt ic Cabling

Fiber optic cable instances:

• High magnetic fields

• Applications that cannot tolerate disruptions• Poorly grounded systems

• Outdoor applications

• Extreme high noise environments




Connectors

• Encapsulated 8-Way Modular Connector (RJ45)

8-way Modular Sealed Jack andPlug in a Metal Housing

8-way Modular Sealed Jack andPlug in a Plastic Housing

C




Connectors

• 4-Pole M12 “D” Coded Connectors

C




Connectors

• Bulkhead Connectors

Use bulkhead connectors sparingly

because they may cause return loss

failures and far-end crosstalk failures.

M12 (IP65/IP67) to IP20 8-WayModular Connector

C t




Connectors

Fiber optic connector types:

• ST

• SC

• LC

• Micro FX

Sealed LC Sealed Micro FX

Eth N t / IP N t k T l i




EtherNet / IP Network Topologies

Network Topology:

• In communication networks, usually a schematic description of the

arrangement of a network:

– Including nodes and connecting lines.

EtherNet / IP Net ork Topologies





Bus Topology:

Tip: This topology is used with many existing Ethernet networkarchitectures but it is seldom used in new architectures.

• Are used when coax media is desired






Star Topology:

Tip: This is the most common topology used in EtherNet/IP networkarchitectures.

• Best suited for environments using twisted pair and/or fiber optic wire






Tree (Combination) Topology:

Tip: The tree topology should also be given careful considerationwhen designing an EtherNet/IP network as it effectively blends the

advantages of a star and bus topology.

Wiring Schemes




Wiring Schemes

Horizontal cable segment must not exceed 100 meters or 90 meters with

two 5 meter jumpers or patch cords.

Three EtherNet/IP wiring schemes:

• Generic Wiring Scheme:

Work AreaCord

Wall Outlet(Telephone)

PLC

PatchCord

Switch

Cross Connect

HorizontalCabling

Wall Outlet(Telephone)

Work AreaCord

I/O

Wiring Schemes




Wiring Schemes

• Semi-Modular Wiring Scheme:

Switch

Work Area

Cord

PLC

Industrial PatchCord

AutomationOutlet

IndustrialWork Area

Cord

I/O

Wiring Schemes




Wiring Schemes

• Point-To-Point Wiring Scheme:

Switch

Work Area

Cord

PLC

Industrial PatchCord

I/O

Grounding and Bonding





Methods for grounding and bonding of equipment:

• Star grounding

• Equipotential grounding






Star grounds converge to one point within the building:

PECommon

CommunicationsCommon

Enclosure

#1

Enclosure

#2

Conductive Path for Noise

Shielded

CommunicationsCable






Shield Termination Method:

DEVICETERMINATION

DEVICE

TERMINATION

.01uF

500V

1 MegMOV

STP Cable

STP Cable

Earth Grounded

Earth Grounded






Equipotential grounding is common in Europe:

Enclosure

#1

Enclosure

#2

Shielded

CommunicationsCablesUnshielded

CommunicationsCable

ShieldedCommunications

Cables

Motor

Network and Operat ional Requirements




et o a d Ope at o a equ e e ts

• Use industrial grade media and components

• Minimize device load due to unwanted IP multicast traffic• Minimize switch load due to unwanted IP multicast traffic

• Minimize network load due to unwanted incoming IP multicast or

broadcast traffic

• Block IP multicast traffic generated within the EtherNet/IP sub-net from

propagation into the plant network

Control network must be separated from the information (office)

environment.

(Continued)

Common practices:





p q

• Block traffic, especially broadcast traffic like streaming video, from plant

network from propagating to the EtherNet/IP sub-net

• Implement standard network troubleshooting tools

• Account for device limitations

• Obtain schematics of existing network architecture(s) and plant floor

devices

• Predict/determine volumes of data to be used in project

(Continued)

Common practices:





p q

• Obtain functional specifications and data costs of EtherNet/IP modules

• Obtain functional specifications and data costs of Ethernet cables, routers,and switches

• Verify final network media

• Obtain IP addresses from IT department for all current and projected

Ethernet and/or EtherNet/IP devices on the EtherNet/IP network

• Make decisions on system implementation

Common practices:

designing an ethernet system

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