Rockwell Automation Ethernet Design Considerations Reference Manual
Reference Manual
Ethernet Design Considerations
Important User Information
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Summary of Changes
This manual contains new and updated information. Changes throughout this
revision are marked by change bars, as shown to the right of this paragraph.
New and Updated Information
This table contains the changes made to this revision.
Top ic Pa ge
Studio 5000™ Logix Designer application is the rebranding of RSLogix™ 5000 software 10
Updated switch selection chart 28
Updated information about network address translation (NAT) 38
Added specifications for the 1756-EN2TRXT, 1756-EN2TSC, and 9300-ENA modules 66, 67, 68
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 3
Summary of Changes
Notes:
4 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Table of Contents
Preface
EtherNet/IP Overview
Ethernet Infrastructure Components
Studio 5000 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 1
Network Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
CIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Configuration Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
IP Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Gateway Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Subnet Mask . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
EtherNet/IP Modules in a Control System . . . . . . . . . . . . . . . . . . . . . . . . . 19
Bridge across Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 2
Topologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Hubs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Repeaters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Media Converters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Routers and Gateways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Unmanaged versus Managed Switches. . . . . . . . . . . . . . . . . . . . . . . . . . 29
Autonegotiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Full-duplex Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Ethernet Infrastructure Features
Chapter 3
Transmission Packets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Default Setting in the Studio 5000 Environment. . . . . . . . . . . . . . . . 33
Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Multicast Address Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Transmission Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Address Resolution Protocol (ARP). . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Domain Name System (DNS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Network Address Translation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Allen-Bradley Products That Support NAT . . . . . . . . . . . . . . . . . . . . 38
Virtual LANs and Segmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
VLAN Trunking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
VLANs and Segmentation Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . 44
Quality of Service (QoS). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
QoS Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Resiliency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Time Calculations in a Logix5000 System . . . . . . . . . . . . . . . . . . . . . . 46
Resiliency Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 5
Table of Contents
Spanning Tree Protocol (STP) and Rapid STP (RSTP) . . . . . . . . . . 48
EtherChannel Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Flex Links Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Resilient Ethernet Protocol (REP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Device-level Ring (DLR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Internet Group Management Protocol (IGMP). . . . . . . . . . . . . . . . . . . . . 55
Port Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Dynamic Secure MAC Address (MAC ID) . . . . . . . . . . . . . . . . . . . . . 56
Static Secure MAC Address (MAC ID) . . . . . . . . . . . . . . . . . . . . . . . . 56
Security Violations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Device Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Chapter 4
EtherNet/IP Protocol
Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
TCP Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
CIP Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
CIP Connection Message Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
CIP Connection Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Nodes on an EtherNet/IP Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
EtherNet/IP Network Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Packets Rate Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
EtherNet/IP Capacity Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Upgrade to Latest Firmware Revision . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Monitor Packet Sizes in Current Application . . . . . . . . . . . . . . . . . . . 70
Requested Packet Interval (RPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Messaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Implicit Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Explicit Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
CIP Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
CIP Sync . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Integrated Motion on an EtherNet/IP Network . . . . . . . . . . . . . . . . . . . . 76
Connectivity to IT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Chapter 5
Predict System Performance
6 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
System Prediction Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Part One: Determine If System Has Sufficient Bandwidth
to Meet Application Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Part Two: Predict Maximum input or Output Times for
CIP Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Performance Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
CompactLogix 5370 Controller Example . . . . . . . . . . . . . . . . . . . . . . . 83
ControlLogix Controller Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Identify and Count Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Calculate Packets/Second . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Estimate the Fastest RPI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Index
Table of Contents
Estimate Maximum Input or Output Times for CIP Connections . 89
Example: Predict System Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Determine If System Has Sufficient Bandwidth
to Meet Application Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Explicit Messaging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
EtherNet/IP Module Serving as a Scanner . . . . . . . . . . . . . . . . . . . . . . 93
EtherNet/IP Modules Functioning as Adapters . . . . . . . . . . . . . . . . . 95
EtherNet/IP Modules 2 and 3 with Consumed Tags . . . . . . . . . . . . 96
Recommendations to Achieve More Throughput
in an Existing Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Estimate the Maximum Input or Output Times
for CIP Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
Refine Estimates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 7
Table of Contents
Notes:
8 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Rockwell Automation uses open network technology for seamless, plant-wide
integration. These open networks share a universal set of communication
services. As a result, information can be communicated seamlessly throughout
the plant and to and from the Internet for e-business applications.
Each Rockwell Automation network is ideal for a wide range of applications,
operates with devices manufactured by various vendors, and shares data with
industry-standard information networks.
Comparison EtherNet/IP Network ControlNet Network DeviceNet Network
Function Plant management system tie-in (material
handling) with configuration, data collection,
and control on a single high-speed network
Typical devices networked • Mainframe computers
• Programmable controllers
• Robots
• HMI
• I/O
• Drives
• Process instruments
Data repetition Large packets, data sent regularly Medium-size packets; data transmissions are
Number of nodes, max No limit 99 nodes 64 total nodes
Data transfer rate 10 Mbps, 100 Mbps, or 1 Gbps 5 Mbps 500, 250, or 125 Kbps
Typical use Plant-wide architecture
High-speed applications
Supports transmission of time critical data
between PLC processors and I/O devices
• Programmable controllers
• I/O chassis
• HMIs
• Personal computers
• Drives
• Robots
deterministic and repeatable
Redundant applications
Scheduled communication
Connects low-level devices directly to
plant-floor controllers without the use of I/O
modules
• Sensors
• Motor starters
• Drives
• Personal computers
• Push buttons
• Low-end HMIs
• Bar code readers
• PLC processors
• Valve manifolds
Small packets; data sent as needed
Supply power and connectivity to low-level
devices
Preface
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 9
Preface
Studio 5000 Environment
The Studio 5000 Engineering and Design Environment combines engineering
and design elements into a common environment. The first element in the
Studio 5000 environment is the Logix Designer application. The Logix Designer
application is the rebranding of RSLogix 5000 software and continues to be the
product to program Logix5000™ controllers for discrete, process, batch, motion,
safety, and drive-based solutions.
The Studio 5000 environment is the foundation for the future of Rockwell
Automation® engineering design tools and capabilities. It is the one place for
design engineers to develop all the elements of their control system.
10 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Preface
Additional Resources
These documents and websites contain additional information concerning
related products from Rockwell Automation.
Table 1 - ODVA Resources
Resource Description
http://www.odva.org/
http://www.odva.org/default.aspx?tabid=54
Ethernet Media Planning and Installation Manual, ODVA publication
http://www.odva.org/Portals/0/Library/Publications_Numbered/
PUB00148R0_EtherNetIP_Media_Planning_and_Installation_Manual.pdf
Network Infrastructure for EtherNet/IP: Introduction and Considerations,
ODVA publication
http://www.odva.org/Portals/0/Library/Publications_Numbered/
PUB00035R0_Infrastructure_Guide.pdf
Table 2 - Rock well Automation Resources
Resource Description
http://www.ab.com/networks/
http://www.rockwellautomation.com/services/networks/
http://www.rockwellautomation.com/services/security/
http://www.ab.com/networks/architectures.html Links to the Education series webcasts for IT and controls professionals.
EtherNet/IP Embedded Switch Technology Application Guide, publication ENET-AP005 Describes how to install, configure, and maintain linear and device-level ring (DLR)
EtherNet/IP QuickConnect Application Technique, publication ENET-AT001
EtherNet/IP Socket Interface Application Technique, publication ENET-AT002 Describes the socket interface used to program MSG instructions to communicate
EtherNet/IP Network Configuration User Manual, publication ENET-UM001 Describes how to configure and use EtherNet/IP communication modules with a
Accesses the Open DeviceNet Vendors Association (ODVA) website.
Accesses the CIP Advantage website. The website offers the following:
• CIP features and benefits
• How to get started
Describes the required media components and how to plan for, install, verify,
troubleshoot, and certify an Ethernet network.
Provides an overview of the technologies used in EtherNet/IP networks and provides
guidelines for deploying infrastructure devices in EtherNet/IP networks.
Accesses the networks and communication section of the Rockwell Automation website.
Accesses Rockwell Automation network and security services websites.
networks by using EtherNet/IP devices with embedded switch technology.
Describes EtherNet/IP QuickConnect technology. QuickConnect technology enables
EtherNet/IP devices to quickly power up and join an EtherNet/IP network.
between a Logix5000 controller via an EtherNet/IP module and Ethernet devices that do
not support the EtherNet/IP application protocol.
Logix5000 controller and communicate with various devices on the Ethernet network.
Table 3 - Cisco and Rockwell Automation Alliance Resources
Resource Description
http://www.ab.com/networks/architectures.html
Converged Plantwide Ethernet (CPwE) Design and Implementation Guide,
publication ENET-TD001
Embedded Switch Technology Reference Architectures, publication ENET-RM003
Links to the Rockwell Automation and Cisco Systems reference architecture website.
Represents a collaborative development effort from Rockwell Automation and Cisco
Systems. The design guide is built on, and adds to, design guidelines from the Cisco
Ethernet-to-the-Factory (EttF) solution and the Rockwell Automation Integrated
Architecture™. The design guide focuses on the manufacturing industry.
Provides design recommendations for connecting device-level topologies to networks
comprised of Layer 2 switches. It also covers the implementation of embedded switch
technology within the Converged Plantwide Ethernet (CPwE) Cell/Area zone.
You can view or download Rockwell Automation publications at
http:/www.rockwellautomation.com/literature/
technical documentation, contact your local Allen-Bradley distributor or
Rockwell Automation sales representative.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 11
. To order paper copies of
Preface
Notes:
12 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Chapter 1
Application
Presentation
Session
Transport
Network
Link
Physical
CIP
Control and Information
Protocol
Ethernet
MAC
Ethernet
Physical
UDP TCP
IP
IP-Multicast
EN50170
Control International
and
IF C 61158 Standard
Request for Comments
IETF
UDP/TCP/IP
IEEE 802.3
OPEN
EtherNet/IP Overview
Top ic Pa ge
Network Protocols 14
Configuration Requirements 15
EtherNet/IP Modules in a Control System 19
Bridge across Networks 20
The EtherNet/IP protocol is a multi-discipline, control and information
platform for use in industrial environments and time-critical applications. The
EtherNet/IP network uses standard Ethernet and TCP/IP technologies and an
open, application-layer protocol called the Common Industrial Protocol (CIP).
The open, application-layer protocol makes interoperability and
interchangeability of industrial automation and control devices on the
EtherNet/IP network a reality for automation and real-time control applications.
The EtherNet/IP protocol follows these standards:
• IEEE 802.3—Standard Ethernet, Precision Time Protocol (IEEE-1588)
• IETF—Internet Engineering Task Force, standard Internet Protocol (IP)
• IEC—International Electrotechnical Commission
• ODVA—Open DeviceNet Vendor Association, Common Industrial
Protocol (CIP)
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 13
Chapter 1 EtherNet/IP Overview
Network Protocols
On the most basic level, Ethernet is a wire or cable that connects computers and
peripheral modules so that they can communicate. The actual wire used for the
network is referred to as the network medium. Beyond the physical medium, all
Ethernet networks support protocols that provide data transfer and network
management capability.
Protocol Description
Common Industrial
Protocol (CIP)
Transmission Control
Protocol/internet Protocol
(TCP/IP)
User Datagram Protocol/
internet Protocol (UDP/IP)
CIP applies a common application layer over an Ethernet network by encapsulating
messages in TCP/UDP/IP. This common application layer provides interoperability and
interchangeability of industrial au tomation and control modules on an Ethernet network.
The EtherNet/IP network supports both real-time I/O (implicit messaging) and explicit
messaging.
TCP/IP is a transport-layer protocol (TCP) and a network-layer protocol (IP) commonly
used in business environments for communication within networks and across
internetworks. The EtherNet/IP communication modules use TCP/IP for explicit
messaging. Explicit messaging is used by applications when time is not a critical factor,
such as uploading or downloading programs.
UDP is a much simpler transport protocol. It is connectionless, and provides a simple
means of sending datagrams between two modules. UDP is used by applications that
implement their own handshaking between modules and require minimal transport
service. UDP is smaller, simpler, and faster than TCP and can operate in unicast, multicast,
or broadcast mode. The EtherNet/IP communication modules use UDP/IP for real-time
I/O messaging.
CIP
CIP is a message-based, application-layer protocol. This protocol implements a
relative path to send a message from the producing modules in a system to the
consuming modules.
CIP uses the producer/consumer networking model instead of a source/
destination (master/slave) model. The producer/consumer model reduces
network traffic and increases speed of transmission.
In traditional I/O systems, controllers poll input modules to obtain their input
status. In the CIP system, digital input modules are not polled by a controller.
Instead, they produce their data either upon a change of state (COS) or at a
requested packet interval (RPI). The frequency of update depends upon the
options chosen during configuration and where on the network the input
module resides. The input module, therefore, is a producer of input data and the
controller is a consumer of the data.
The controller can also produce data for other controllers to consume. The
produced and consumed data is accessible by multiple controllers over the Logix
backplane and over the EtherNet/IP network. This data exchange conforms to
the producer/consumer model.
14 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
EtherNet/IP Overview Chapter 1
Class A
Class B
Class C
Network (7 bits)
Network (14 bits)
Network (21 bits)
Local Address (8 bits)
Local Address (16 bits)
Local Address (24 bits)
Class D
Multicast Address (28 bits)
0
0
8
8
8
8
0
0
0
16
16
16
24
24
24
31
31
31
31
1
0
1
0
1
11 1
0
Configuration Requirements
All devices on Ethernet communicate by using the Ethernet address for the
device. This address is sometimes referred to as the hardware address or Media
Access Controller (MAC) address. The hardware address is a unique, six-byte
address, which is embedded in the circuitry of every device on an Ethernet
network. Every vendor of Ethernet products obtains their own unique address
range.
For a device to communicate on an Ethernet network, you must configure its
IP address, gateway address, and subnet mask.
IP Address
The IP address identifies each node on the IP network or system of connected
networks. Each TCP/IP node on a network must have a unique IP address. The
IP address is 32 bits long and has a network ID part and a host ID part. Because
networks vary in size, there are four types of networks.
Network Type Application
Class A Large networks with many devices
Class B Medium-sized networks
Class C Small networks (fewer than 256 devices)
Most common for private, industrial networks
Class D Multicast addresses
The network class determines how an IP address is formatted.
16
24
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 15
Chapter 1 EtherNet/IP Overview
Each node on the same physical network must have an IP address of the same
class and must have the same network ID. Each node on the same network must
have a different local address (host ID), thus giving it a unique IP address.
IP addresses are written as four-decimal integers (0...255) separated by periods
where each integer gives the value of one byte of the IP address.
For example, the following 32-bit IP address is written as 130.0.0.1:
10000010 00000000 00000000 00000001
Class Leftmost Bits Start Address Finish Address
A0xxx 0.0.0. 127.255.255.255
B10xx 128.0.0.0 191.255.255.255
C110x 192.0.0.0 223.255.255.255
D 1110 224.0.0.0 239.255.255.255
Public IP addresses are for computers and devices connected to the Internet.
Devices on industrial networks are not connected to the Internet, but they
communicate with each other over an EtherNet/IP network. These devices use
private IP addresses that are not routed on the Internet.
Private IP addresses typically start with 10, 172, or 192 as the first part of the
address. Private IP addresses are typically connected to the Internet through a
Network Address Translation (NAT) device.
For more information about NAT, see page 38
.
16 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
EtherNet/IP Overview Chapter 1
Network 1
Network 2
A
B
C
G
128.1.0.2
128.2.0.3
128.2.0.2
128.2.0.1
128.1.0.1
Gateway Address
A gateway connects individual physical networks into a system of networks.
When a node needs to communicate with a node on another network, a gateway
transfers the data between the two networks. The following figure shows
gateway G connecting Network 1 with Network 2.
When host B with IP address 128.2.0.1 communicates with host C, it knows
from C’s IP address that C is on the same network. In an Ethernet environment,
B can then resolve C’s IP address to a MAC address and communicate with C
directly.
When host B communicates with host A, it knows from A’s IP address that A is
on another network because the network IDs differ. To send data to A, B must
have the IP address of the gateway connecting the two networks. In this example,
the gateway’s IP address on Network 2 is 128.2.0.3.
The gateway has two IP addresses (128.1.0.2 and 128.2.0.3). Network 1 hosts
must use the first IP address, and Network 2 hosts must use the second IP
address. To be usable, a host’s gateway IP address must match its own net ID.
Devices with IP address switches use the default gateway address of either
192.168.1.1 or 0.0.0.0. Check your product information to determine which
gateway address applies for your device.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 17
Chapter 1 EtherNet/IP Overview
128.1.0.1
128.2.64.1
128.2.64.3
128.1.0.2
Network 1
Network 2.1
128.2.128.1 128.2.128.2
128.2.128.3
128.2.64.4
128.1.0.1
128.2.64.1
128.2.128.1
128.2.64.2
128.2.128.2
128.1.0.2
128.2.64.3
128.2.128.3
A
B
C
G
G2
DE
Network 2.2
Subnet Mask
Subnet addressing is an extension of the IP address scheme. It enables a site to use
a single net ID for multiple physical networks. Routing outside of the site
continues by dividing the IP address into a net ID and a host ID via the IP class.
Inside a site, the subnet mask is used to redivide the IP address into a custom net
ID portion and host ID portion.
A subnet mask determines which of the 32 bits in the IP address are part of the
network ID and which are part of the unique node identification. This also
determines the size of the network or subnetwork.
Take Network 2 (a Class B network) in the previous example and add another
physical network. Selecting this subnet mask adds two additional net ID bits
providing for four physical networks.
11111111 11111111 11111111 00000000 = 255.255.255.0
Two bits of the Class B host ID have been used to extend the net ID. Each unique
combination of bits in the part of the host ID where subnet mask bits are 1
specifies a different physical network.
A second network with hosts D and E has been added. Gateway G2 connects
network 2.1 with network 2.2. Hosts D and E use gateway G2 to communicate
with hosts not on network 2.2. Hosts B and C use gateway G to communicate
with hosts not on network 2.1. When B is communicating with D, G (the
configured gateway for B) routes the data from B to D through G2.
18 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
EtherNet/IP Overview Chapter 1
Switch
1756-EN2T
1756 I/O Modules
1794-AENT
1794 I/O Modules
Work stat ion
1734-AENT
1734 I/O Modules
PowerFlex®
Drive
1783-ETAP
Work stat ion
1783-ETAP
1756-EN2TR
1756 I/O Modules
1769-L18ERM-BB1B Control System
1769-L33ERM Control System
PanelView™ Plus Terminal Connected
Via a 1783-ETAP EtherNet/IP Tap
1794-AENTR FLEX™ I/O Adapter
1734-AENTR POINT I/O™ Adapter
with POINT I/O Modules
Kinetix 6500 Drives
with Motors
Kinetix 350 Drive
with Motor
EtherNet/IP Modules in a Control System
The following diagram shows how EtherNet/IP communication modules can fit
into a control system.
In this example, the following actions can occur:
• Controllers produce and consume tags with each other.
• Controllers initiate MSG instructions to send/receive data or configure
devices.
• Controllers control I/O and drives.
• Workstations can upload/download projects to the controllers.
• Workstations can configure devices on the EtherNet/IP network.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 19
Chapter 1 EtherNet/IP Overview
IMPORTANT
Bridge
EtherNet/IP
Panel View Pl us
Terminal
DeviceNet
Drive
Switch
Bridge across Networks
Some EtherNet/IP communication modules support the ability to bridge or
route communication through devices, depending on the capabilities of the
platform and communication devices.
You have a bridge when you have a connection between communication devices
on two networks. For example, the bridge device has both EtherNet/IP and
DeviceNet connections, enabling Device 1 on the EtherNet/IP network to
communicate with Device 2 on a DeviceNet network through the bridge.
The bridge device can be an EtherNet/IP-to-DeviceNet bridging device or a
Logix5000 system with an EtherNet/IP communication module and a
DeviceNet communication module.
CIP messages originating on this network Can bridge to this network
EtherNet/IP ControlNet DeviceNet RS-232 Serial
EtherNet/IP Yes Yes Yes Yes
ControlNet Yes Yes Yes Yes
RS-232 Yes Yes Yes Yes
In the following example graphic, a workstation configures a drive on a
DeviceNet network and bridges EtherNet/IP networks to reach the drive.
You can bridge between devices on different networks for only messaging.
You cannot bridge from one network to another for I/O control or
produced and consumed tags. This restriction applies regardless of whether
the two networks are either of the following:
• Same type, such as an EtherNet/IP network to an EtherNet/IP network
• Different types, such as an EtherNet/IP network to a ControlNet network
20 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Ethernet Infrastructure Components
Top ic Pa ge
Topologies 22
Media 24
Hubs 25
Repeaters 25
Media Converters 26
Bridges 26
Routers and Gateways 27
Switche s 28
Chapter 2
The topology and cable layout of the Ethernet network is part of the physical
layer. Ethernet systems require various infrastructure components to connect
individual network segments.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 21
Chapter 2 Ethernet Infrastructure Components
Switch
D D D
D D
Switch
Switch
SwitchSwitch
D
D
D
D
D D
Switch
D D
Switch
D D
Switch
D D
Layer 3 Layer 3
Layer 2
D D
Layer 2
D D
Topologies
Ethernet networks are laid out in point-to-point configurations with one cable
for each device. Ethernet networks have active infrastructures that rely on
switches. You can design a network with individual switch devices and devices
with embedded switch technology.
Table 4 - Topologies with an Individual Switch
Topology Description
Star The most common EtherNet/IP network topology is a star, where end devices are connected and
Ring—switch based A ring network is a single-fault tolerant ring network intended for the interconnection of automation
communicate with each other via a switch. In a star topology, nodes are typically grouped closely
together.
Advantag es
• Easy to design, configure, and implement
• Direct path between the infrastructure device
and the end device
• Remove and add devices without affecting the
rest of the network
• Increase port capacity on the switch to add
more devices
• Centralization can ease troubleshooting,
because the switch sees the activities of all of
the connected devices
devices.
Advantag es
• Ability to survive a single point of failure or a
device being powered down on the ring.
• Simplified cabling
• Ability to cover long distances with 100 m
between each copper segment
Disadvantages
• Loss of network service in case of connection
failure (no resiliency)
• Primarily the single point of failure of the
centralized sw itch
Disadvantages
• Additional configuration complexity
• Longer convergence times
• Variable number of hops can make
performance difficult to predict
Linear—switch based A linear network is a collection of devices that are daisy-chained together.
A linear topology works best for a limited number of nodes.
Advantag es
• Easy to design, configure, and implement
• Least amount of cabling
• Minimal amount of cable needed
• Ability to cover long distances with 100 m
between each link
Redundant star In a redundant star topology, every Layer 2 access switch has dual connections to a Layer 3 distribution
22 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
switch. Devices are connected to the Layer 2 switches.
Advantag es
• Resiliency from multiple connection failures
• Faster convergence to connection loss
• Consistent number of hops provide
predictable and consistent per formance
• Fewer bottlenecks
Disadvantages
• Loss of network service in case of connection
failure (no resiliency)
• Creates the potential for bottlenecks
• Variable number of hops can make
performance difficult to predict
• Powering down a device or the failure of a
device in the center of the network affects
connectivity between any of the devices on
either side
• Each link in the chain represents network
delay
Disadvantages
• Additional wiring and ports required
• Additional configuration complexity
Ethernet Infrastructure Components Chapter 2
D
D D
D
D
D
D D
The EtherNet/IP embedded switch technology offers alternative network
topologies by embedding switches into the end devices themselves.
Table 5 - Topologies with Embedded Switch Technology
Topology Description
Device-level ring (DLR)—embedded switch A DLR network is a single-fault tolerant ring network intended for the interconnection of automation devices. This
topology is also implemented at the device level. No additional switches are required.
Advantages
• Ability to survive a single point of failure or a device
being powered down on the ring.
• Simplified cabling
• Ability to cover long distances with 100 m between
Disadvantages
• Supervisor-node configuration required
• Additional configuration complexity
• Variable number of hops can make performance
difficult to predict
each copper segment
• Very fast network convergence
Linear—embedded switch A linear network is a collection of devices that are daisy-chained together. The EtherNet/IP embedded switch technology
enables this topology to be implemented at the device level. No additional switches are required.
A linear topology works best for a limited number of nodes.
Advantages
• Easy to design, configure, and implement
• Least amount of cabling
• Minimal amount of cable needed
• Ability to cover long distances with 100 m between
each link
Disadvantages
• Loss of network service in case of connection failure (no
resilie ncy)
• Creates the potential for bottlenecks
• Variable number of hops can make performance
difficult to predict
• Powering down a device or the failure of a device in the
center of the network affects connectivity between any
of the devices on either side
• Each link in the chain represents network delay
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 23
Chapter 2 Ethernet Infrastructure Components
Do you have any of these:
• Long distances?
• High Magnetic fields?
• High noise?
Fiber Media
Recommendations:
• Multi-mode for general purposes, cost less
• Single-node yields higher dista nce, but
costs more
Do you have excess
amounts of any of these:
• Radiated noise?
• Conducted noise?
• Metal conduit?
Copper STP (shielded twisted pair)
Recommendations:
• Requires proper grounding
• Category 5e, 6, and 6a cables and
connectors
Copper UTP (unshielded twisted pair)
Recommendations:
• Requires proper grounding
• Category 5e, 6, and 6a cables and comectors
Yes
Yes
No
No
Media
The actual wire used for the network is referred to as the physical media.
Generally, shorter cable runs are less susceptible to EMI (electromagnetic
interference) and RFI (radio-frequency interference) from electrical circuits,
motors, and other machinery.
Figure 1 - Select Ethernet Media
For more information about the media options, see the Ethernet section of the
Network Media Catalog, publication M116-CA552
24 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
.
Ethernet Infrastructure Components Chapter 2
Hub
HMI
1756 Controller
1734 POINT I/O
Power Flex
1738 ArmorPOINT® I/O
Personal computer
Repeater
Hubs
Hubs are multiport repeaters. They are based on older technology, which has
been largely replaced by network switches at Layer 2, but they are still used as
network diagnostic tools to analyze network traffic:
• A hub is at the center of a star topology.
• Hubs can connect together with a variety of media as a backbone between
hubs.
• A hub broadcasts everything it receives on any channel out all other
channels.
Repeaters
A repeater recreates the incoming signal and re-transmits it without noise or
distortion that can have affected the signal as it was transmitted down the cable.
Repeaters are generally used in older networks to increase the network length.
More modern networks use fiber media or switches to increase network length.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 25
Chapter 2 Ethernet Infrastructure Components
Fiber Link
Ethernet
Ethernet
Ethernet
Tok en R in g
Bridge
Bridge
Ethernet Ethernet
Access Poi nt
Work Group Bridge
Media Converters
Media converters let you mix fiber and copper (twisted-pair) cables in the same
system.
Use a switch to mix media:
• Physical layer devices offer no buffering or advanced diagnostic features.
• Physical layer devices are easily overrun by an EtherNet/IP system (no
buffering = lost data).
• Layer 2 devices have buffering, QoS, and other management features.
Bridges
A bridge is a device that isolates traffic between segments by selectively
forwarding frames to their proper destination. A bridge is transparent to the
network and protocol independent. More advanced devices that perform the
same bridging function are commonly used instead of a bridge.
26 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Ethernet Infrastructure Components Chapter 2
Routing Table
Network
Port
10.17.10.0
10.10.10.0
1
2
10.17.10.56
VLAN 17
Subnet 10.17.10.0
Subnet Mask
255.255.255.0
1
0
.
1
0
.
1
0
.
5
6
Default Gateway
10.10.10.1
10.17.10.1
VLAN 10
Subnet 10.10.10.0
Subnet Mask
255.255.255.0
Routers and Gateways
Routers and gateways use the network portion of IP addresses to identify the
location of networks. A routing table lets a device know from which port to
transmit a message, so the message can get to a particular network. If that
network is not directly attached to the device, it forwards the message to the next
gateway or router in the path for further routing.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 27
Chapter 2 Ethernet Infrastructure Components
Yes
No
Yes
No
No
Do you connect to another
network infrastructure device,
such as a switch or router?
Do you ne ed Layer 3 routin g?
Select a Stratix 8300 modular, managed switch:
• 1783-RMS06T 4 ports copper, 2 ports copper/fiber
• 1783-RMS10T 8 ports copper, 2 ports copper/fiber
Optionally, add expansion ports:
• 1783-MX08T 8 ports copper
• 1783-MX08F 8 ports fiber
• 1783-MX04S 4 ports SFP
• 1783-MX08S 8 ports SFP
• 1783-MX04E 4 ports PoE
• 1783-MX4T04E 4 ports PoE + 4 ports 10/100
Select a Stratix 8000 modular, managed switch:
• 1783-MS06T
• 1783-MS10T
Optionally, add expansion ports:
• 1783-MX08T 8 ports
• 1783-MX08F 8 ports copper
• 1783-MX04S 4 ports SFP
• 1783-MX04E 4 ports PoE
• 1783-MX4T04E 4 ports PoE + 4 ports 10/100
Do you need any of these:
• Network segmentation
• Diagnostic information
• Port security
• Traffic management
• Network resiliency
Do you need any of these?
• More than 20 ports
• More than 4 fiber ports
• More than 4 PoE ports
Select a Stratix 2000™ unmanaged switch:
• 1783-US03T01F 3 ports copper, 1 port fiber
• 1783-US05T 5 ports copper
• 1783-US06T01F 6 ports copper, 1 port fiber
• 1783-US08T 8 ports copper
Select a Stratix 5700 conf igurable, managed switch:
• 1783-BMSxxx 6 port versions
• 1783-BMSxxx 10 port versions
• 1783-BMSxxx 20 port versions
Yes
No
Yes
Switches
Figure 2 - Select an Ethernet Switch
Switches provide determinism and throughput required for control applications.
Industrial-rated switches are recommended for connecting computers and other
devices to each other and to higher-level networks in the network reference
architecture. Ethernet switches perform the following:
• Operate in Full-duplex mode to eliminate collisions
• Include managed switch features for advanced network functionality
For more information, see the Stratix Switch Reference Chart, publication
ENET-QR001
.
28 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
Ethernet Infrastructure Components Chapter 2
Unmanaged versus Managed Switches
Unmanaged switches are relatively inexpensive and simple to set up, but they do
not provide any management capabilities, security, or diagnostic information.
Therefore, they are difficult to troubleshoot.
As a general rule for unmanaged switches, make sure of the following:
• Your application does not contain I/O traffic
or
• Your application has I/O control and the following is true:
– The network is not directly connected to the IT network
– All nodes on the network are Rockwell Automation devices
– There is no potential to overload a device with traffic
Managed switches are typically more expensive than unmanaged switches and
require some level of support for initial configuration and replacement. However,
managed switches provide advanced features, which can enable better network
performance in your control system. Managed switches are able to manage
multicast traffic and provide diagnostics data, security options, and other
advanced features.
Switch Type Advantages Disadvantages
Managed • Ability to manage multicast traffic
• Diagnostics data
• Security options
• Additional advanced features
• Network segmentation features
• Network resiliency features
Unmanaged • Inexpensive
• Simple to set up
• 'No Config' replacement
• More expensive
• Requires some level of support and
configuration to start up and replace
• No network segmentation
• No dagnostic information
• No port security
• No traffic management
• No network resiliency
Autonegotiation
Autonegotiation lets devices select the optimal way to communicate without
requiring you to configure the devices. However, if you connect a
manually-configured device to an autonegotiation device, a high rate of data
transmission errors can occur.
All 100 Mbps devices are required to support autonegotiation, but most existing
10 Mbps devices do not. Select a switch that supports both speeds to enable you
to connect to existing devices that use the slower rate.
Rockwell Automation Publication ENET-RM002C-EN-P - May 2013 29
Chapter 2 Ethernet Infrastructure Components
Full-duplex Mode
Ethernet is based on Carrier Sense Multiple Access/Collision Detect (CSMA/
CD) technology. This technology places all nodes on a common circuit so they
can all communicate as needed. The nodes must handle collisions (multiple
devices talking at the same time) and monitor their own transmissions so that
other nodes have transmission time.
The data transmission mode you configure determines how devices transmit and
receive data.
Tran smiss ion Mo de Featu res
Full-duplex Dete rministic
• Transmit and receive at the same time
• Transmit on the transmit pair and receive on the receive pairs
• No collision detection, backoff, or retry
• Collision free
Half- duplex Nondeterministic
• One station transmits and the others listen
• While transmitting, you do not receive, as no one else is transmitting
• If someone else transmits while you are transmitting, then a collision occurs
• Any Receive-while-Transmit condition is considered a collision
Full-duplex mode eliminates collisions. Combined with the speed of the switches
available today, you can eliminate the delays related to collisions or traffic in the
switch. A a result, the EtherNet/IP network becomes a highly deterministic
network well-suited for I/O control:
• If you are autonegotiating, make sure you verify the connection.
• If you are forcing speed and duplex on any link, make sure you force at
both ends of the link. If you force on one side of the link, the
autonegotiating side always goes to half-duplex.
30 Rockwell Automation Publication ENET-RM002C-EN-P - May 2013
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