EtherNet

EtherNet/IP Design and Configuration

Designing an EtherNet/IP Cable System

Pinging a Module’s EtherNet/IP Address

Configuring and Modifying EtherNet/IP Addresses Using

BOOTP-DHCP Server Software

Configuring and Modifying EtherNet/IP Addresses Using

RSLinx Software

Producing and Consuming Data over an EtherNet/IP Network

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EtherNet/IP Network Overview CIP (Common Industrial Protocol):

• Enables I/O control over an EtherNet/IP network • Bridges EtherNet/IP devices with devices on

networks such as ControlNet 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.

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EtherNet/IP Network Overview

OSI (Open System Interconnection) Model:

• Consists of seven layers

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

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EtherNet/IP Network Overview

IP Network

TCP, UDP Transport

Session

Presentation CIP, CSP, HTTP

FTP,TELNET

Application

Protocol Layer

Correlating the seven layers with common protocols:

10/100baseT, Transceiver, etc.

Physical

Ethernet Data Link

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EtherNet/IP Network Hardware Components

Switch:

Incoming messages

are only transmitted

to desired node.

Switches selectively

route packets of

information to specific

devices.

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Switch Selection

Benefits of a managed switch: • Monitor the performance of the network

• Set up broadcast domains

• Run single computers on managed switch ports

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Switch Selection

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 than with a physical picture of the LAN:

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Switch Selection

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.

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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)

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EtherNet/IP Network Topologies

Bus Topology:

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

• Are used when coax media is desired

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EtherNet/IP Network Topologies

Star Topology:

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

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

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EtherNet/IP Network Topologies Tree (Combination) Topology:

Tip: The tree topology should also be given careful consideration when designing an EtherNet/IP network as it effectively blends the advantages of a star and bus topology.

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Overview of IP Addresses

IP (Internet Protocol) Address:

• User-defined software address assigned to a device

• Identifies network and node

• 32-bit address normally grouped into 4 bytes (e.g., 10.88.244.130).

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Sample view of an IP address (131.107.16.200)

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MAC (Media Access Control) Address:

MAC Address (also referred to as a module's Ethernet address)

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Classes of IP Addresses

Four different classes of IP addresses:

Net ID Host ID 0 1 1 Class C

Net ID Host ID 0 1 Class B

Net ID Host ID 0

0 1 2 8 16 24 31

Class A

Class D Used for Multicast Messages

• IP address used determines number of possible networks and end devices.

• Classes are determined by first few bits of each IP address:

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Classes of IP Addresses

Class Initial Byte Values Typical Users/Uses

A 1 - 127 Very large networks

B 128 - 191 Medium-sized networks

C 192 - 223 Small to mid-size businesses

D 224 - 239 Multicast messaging

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Private IP Addresses

Class Private IP Addresses

A 10.0.0.0 - 10.255.255.255

B 172.16.0.0 - 172.31.255.255

C 192.168.0.0 - 192.168.255.255

• Finite number of IP addresses have been designated as private IP

addresses.

• Private IP addresses prohibit message traffic from being routed to Internet

thereby avoiding conflicts that would otherwise arise whenever two or more

enterprises used same IP address.

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How a Subnet Mask Operates

A subnet mask, like an IP address, is a 32-bit address that is normally

grouped into 4 bytes for ease of communication and understanding:

Typical Subnet Mask

Binary Equivalent

Consecutive “1's” Represent Network Portion of IP Address

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How a Subnet Mask Operates

A subnet mask uses "1's" to do bit-by-bit comparison of two IP addresses to

see if devices associated with IP address are on same subnet:

• As long as IP address bits match each other (independent of the subnet

mask value) whenever there is a corresponding “1” in the subnet mask,

devices are on same subnet.

• If network portions:

– Match up, devices communicate directly with each other

– Don't match up, they are on separate networks and then communicate through a

router (commonly referred to as a gateway).

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Example

Compare addresses of 2 devices and determine if they are on same subnet:

EtherNet/IP Address: 165.88.73.129


Subnet Mask: 255.255.240.0

Converting these decimal values to their binary equivalent yields:

EtherNet/IP Address:


Subnet Mask:

Corresponding bits match each other; therefore, these two devices are on the same subnet.

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Example Compare same 2 addresses of 2 devices using different subnet mask and

determine if they are on same subnet:



Subnet Mask: 255.255.255.0

Converting these decimal values to their binary equivalent yields:



Subnet Mask:

Corresponding bits do not match each other; therefore, these two devices are not on the same subnet.

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Ping

Ping Command

Device Is Active on the Network

Device Is Not Active on the

Network

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Ping

Successful (ping) returns are an indication that:

A successful ping command does not

guarantee that a particular device is active.

A successful ping identifies that a device

with the identified IP address is active on the

network.

• A device is active on the network with the IP address used by the ping

command.

• Error is not caused by a faulty cable

• Error is not the result of a problem with the router or switch

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ARP (Address Resolution Protocol)

The arp (arp -a) command is a protocol for mapping an Internet Protocol

address (IP address) to a MAC address that is recognized in the local network.

To be most effective in mapping the two different addresses together, it should

be executed after the ping command has been executed on one or more IP

addresses.

IP and MAC address pairing list

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• BOOTP (Bootstrap Protocol)

• BOOTP Server

• BOOTP-DHCP (Bootstrap Protocol-Dynamic Host Configuration Protocol) Server Software

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Relation List:

• Entering corresponding MAC and IP addresses into BOOTP table allows

simultaneous assignment of IP addresses to multiple modules.

Address assignments do not take

effect unless the device is

configured for BOOTP operation

and a power-cycle occurs on the

device.

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BOOTP-DHCP Server software main window:

Relation List Pane

Relation List

Request History

Pane

Request Type

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• in BOOTP Server by right-clicking an entry in the Relation List and

selecting Reset Module's Network Settings to Factory Defaults

• in the RSWho window of RSLinx software via the Module Configuration

dialog box

Tip: BOOTP-DHCP Server can only change a device's IP address if its

setting for Network Configuration Type is dynamic (obtain IP address from

BOOTP Server). This setting can be restored using one of the following

methods:

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

30


BOOTP-DHCP Server software configuration screens:

Relationship between a Device's MAC Address and its IP Address

Network and Host Part Identification

Address of Gateway (or Router) Capable of Routing Messages to Remote Network

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RSLinx Software

From within the RSLinx RSWho window, a module’s EtherNet/IP address or subnet mask can be modified.

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RSLinx Software

RSLinx software configuration screen:

Address of the Device You Are Configuring or Modifying

Network and Host Part Identification

Address of the Gateway (or Router) Capable of Routing Messages to Remote Networks

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Produce/Consume Model Communication model based on content of data rather than source or destination of data:

• Devices that need data (consumers) recognize data they need and consume it (at a specified rate).

• Data is sent on network in single message, no matter how large the number of nodes to which it

needs to go.

• All consumer nodes receive and “consume” information simultaneously.

• Receipt of information is synchronized:

– Bandwidth is conserved since information is "produced" once to multiple

“consumers.”

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Produce/Consume Model

To limit the number of connections

used, consider grouping data into

an array or a user-defined data type

and producing only that array or

structure.

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Produced and Consumed Tag Requirements

• Tags must be data type that is:

– 32 bits or larger (e.g., DINT, REAL, TIMER, COUNTER, etc.)

– Array of these data types

– User-defined data type.

• Data must be less than or equal to 500 bytes.

Data that meets following requirements can be shared by controllers without using ladder logic (i.e.,

message instructions):

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Produced and Consumed Arrays

• Create user-defined data type containing single member:

– Make single member array of desired type

• Copy this user-defined data type to both controllers

• Produce and consume tags of this data type

If a user-defined structure is

produced, there must be a structure

with the identical size and layout in

the consuming controller. To ensure

accuracy, copy the structures

between projects.

BOOL, SINT, and INT arrays can be indirectly produced and consumed:

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• Define a user-defined data type with two members:

– Name first member Status and assign it a DINT data type

– Make second member an array of INTs

You can consume an array of INTs from a PLC-5C controller over a ControlNet network:

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Creating a Produced Tag

Produce Option

Maximum Number of Consumers

Tag Name - Required to Configure Consumed Tag(s)

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Creating a Consumed Tag

Must Be in Consuming Controller's I/O Configuration

Tag Name

RPI for Consumed Tag

Exact Match Required

Must Be Exact Name of the Produced Tag

41


A produced tag should be

consumed by only one tag in a

consuming controller. Multiple

consumed tags within a controller

using the same produced tag will

result in unpredictable controller-to-

controller behavior.

If a consumed tag connection

faults, all other tags being

consumed from the producing

controller will also stop receiving

data.

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The Remote Data (source tag

name) must be exactly the same as

the produced tag name in the

producing controller.

Tip: For accuracy, the source project should be opened and the tag names should be copied.

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EtherNet