Rockwell Automation EtherNet/IP Original Instructions

Application Technique

Original Instructions

EtherNet/IP Socket Interface

Summary of Changes

This publication contains the following new or updated information. This list includes substantive updates only and is not intended to reflect all changes.

Top ic Pa ge

Added ControlLogix® 5580 controllers, GuardLogix® 5580 controllers, CompactLogix™ 5380 controllers, Compact GuardLogix 5380 controllers, Compact GuardLogix 5370 controllers, CompactLogix 5480 controllers,

Added Disable the Socket Object With a MSG Instruction. 18

Throughout

2 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Preface

Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Chapter 1

Socket Interface Architecture Socket Interface Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Number and Type of Sockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Typical Sequence of Transactions for a TCP Client . . . . . . . . . . 10

Typical Sequence of Transactions for a TCP Server. . . . . . . . . . . 11

Typical Sequence of Transactions for UDP without

OpenConnection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Typical Sequence of Transactions for UDP with

OpenConnection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Communicate with the Socket Object Via a MSG Instruction . . . . 14

Service Timeouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

MSG Instruction Timeouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Socket Instance Timeouts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Disable the Socket Object With a MSG Instruction . . . . . . . . . . . . . . 18

Programming Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

TCP Connection Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

ControlLogix Enhanced Redundancy . . . . . . . . . . . . . . . . . . . . . . . 20

EtherNet/IP Module Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Change Controller Mode between Run and Program . . . . . . . . . 22

Application Messages and TCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Application Messages and Inhibited Modules . . . . . . . . . . . . . . . . 23

Partial Reads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Partial Writes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Performance Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Chapter 2

Socket Object Services Socket Create . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

OpenConnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

AcceptConnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

ReadSocket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 3

Table of Contents

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

WriteSocket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

DeleteSocket. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

DeleteAllSockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

ClearLog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

JoinMulticastAddress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

DropMulticastAddress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

MSG Source Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

MSG Source Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Chapter 3

Socket Attributes Access Socket Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Socket Class Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Socket Instance Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Chapter 4

Troubleshoot Socket Applications Diagnostic Webpages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Debugging Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Error Codes for Socket Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Knowledgebase Articles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Index

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Preface

This publication describes the socket interface that you can use to program MSG instructions to communicate between a Logix 5000™ controller via an EtherNet/IP™ module and Ethernet devices that do not support the EtherNet/IP application protocol, such as barcode scanners, RFID readers, or other standard Ethernet devices.

Additional Resources

These documents contain additional information concerning related products from Rockwell Automation.

Resource Description

Ethernet Design Considerations Reference Manual, publication ENET-RM002

Embedded Switch Technology Reference Architectures Reference Manual, publication ENET-RM003

EtherNet/IP Network Devices User Manual, publication

ENET-UM006

Industrial Automation Wiring and Grounding Guidelines, publication 1770-4.1

Product Certifications website rok.auto/ce rtificati ons

You can view or download publications at rok.auto/literature

Provides a general description of the EtherNet/IP protocol and how to use an EtherNet/IP network.

Provides design recommendations for connecti ng devicelevel topologies to larger, switch networks comprised of Layer 2 access switches.

Describes how you can use EtherNet/IP communication modules with your Logix 5000 controller and communicate with various devices on the Ethernet network.

Provides general guidelines for installing a Rockwell Automation industrial system.

. Provides declarations of conformity, certificates, and

other certification details.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 5

Preface

Notes:

6 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Socket Interface Architecture

Top ic Pag e

Socket Interface Architecture 8

Communicate with the Socket Object Via a MSG Instruction 14

Service Timeouts 16

MSG Instruction Timeouts 16

Socket Instance Timeouts 17

Disable the Socket Object With a MSG Instruction 18

Programming Considerations 20

Performance Considerations 25

Chapter 1

The socket interface lets a Logix 5000™ controller communicate via an EtherNet/IP™ module with Ethernet devices that do not support the EtherNet/IP application protocol. Such devices include barcode scanners, RFID readers, or other standard Ethernet devices.

Socket services are available with these modules:

• ControlLogix® 5580 and GuardLogix® 5580 controllers,

• CompactLogix™ 5380 and Compact GuardLogix 5380 controllers

• CompactLogix 5370 and Compact GuardLogix 5370 controllers

• CompactLogix 5480 controllers

• 1756-EN2x, 1756-EN3TR, and 1756-EN4TR EtherNet/IP communication modules

• 1756-EWEB and 1768-EWEB EtherNet/IP web server modules

IMPORTANT MicroLogix™ 1400 controllers also support socket capability, but the

information in this document does not apply to those products. For details on those products, see the MicroLogix 1400 Programmable Controllers Reference Manual, publication 1766-RM001D

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 7

Chapter 1 Socket Interface Architecture

Before you use the socket interface, make sure that you are familiar with these concepts:

• Basic TCP/IP, UDP, and socket programming concepts

• How to write socket programs in a programming language, such as C or Visual Basic

• How to use diagnostic tools, such as a network sniffer

• The application protocols of the devices and applications with which the Logix 5000 controller communicates

• How to write ladder logic or Structured Text for a Logix 5000 controller

Socket Interface Architecture

The socket interface is implemented via the socket object in the EtherNet/IP module. Logix 5000 controller programs communicate with the socket object via MSG instructions. MSG requests to the socket object are similar to socket API calls in most computer operating systems. The socket object services let you open connections, accept incoming connections, send data, and receive data.

To communicate with another device, you must understand the application protocol of the device. The EtherNet/IP module has no application protocol knowledge. The module makes only the socket services available to programs in Logix 5000 controllers.

Number and Type of Sockets

Number of supported socket instances:

32 Socket Instances 20 Socket Instances

• ControlLogix 5580 controllers

• GuardLogix 5580 controllers

• CompactLogix 5480 controllers

• CompactLogix 5380 controllers

• Compact GuardLogix 5380 controllers

• CompactLogix 5370 controllers

• Compact GuardLogix 5370 controllers

• 1756-EN2x EtherNet/IP communication modules

• 1756-EN3TR EtherNet/IP communication module

• 1756-EN4TR EtherNet/IP communication module

• 1756-EWEB EtherNet/IP web server module

• 1768-EWEB EtherNet/IP web server module

Each instance can be one of these types:

• UDP socket—Sends and receives UDP datagrams.

• TCP client socket—The Logix 5000 program initiates the connection.

• TCP server socket—Another device initiates the connection to the Logix 5000 program.

• TCP listen socket—Listens on a specified port number for incoming connections.

8 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Socket Interface Architecture Chapter 1

These options are available for UDP and TCP send and receive services.

Type Communication Send (Write) Receive (Read)

UDP Unicast Yes Yes

Multicast Yes Yes

Broadcast Yes Yes

TCP Uni cas t Yes Yes

Multicast — —

Broadcast — —

You must have a listen socket for each TCP port number that accepts connections. Multiple TCP server sockets can share a listen socket if the connections are made to the same port number.

You can partition the available socket instances between UDP and TCP sockets in these ways:

• Use all instances for client TCP connections.

• Use one instance to listen for incoming TCP connections and then accept the remaining connections from other devices.

• Perform both TCP client and server operations.

• Perform both TCP and UDP operations.

These socket services are available.

Socket Service Socket Instance Page

Socket Create Server or client 28

OpenConnection Client 30

AcceptConnection • If you issue an AcceptConnection service, the instance is a listen type.

• If the AcceptConnection service returns an instance as a result of an incoming connection request, the socket instance is a server type.

ReadSocket Server or client 34

WriteSocket Server or client 36

DeleteSocket Server or client 38

DeleteAllSockets Server or client 39

ClearLog Server or client 40

JoinMulticastAddress Server or client 41

DropMulticastAddress Server or client 42

Once you open a connection on a client socket instance, you cannot use the same socket instance to accept incoming connections. Similarly, if you accept connections on a socket instance, you cannot then use the instance to open outgoing connections. This behavior is consistent with standard socket API behavior.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 9

Chapter 1 Socket Interface Architecture

Controller

EtherNet/IP Module

192.168.1.10

Device

192.168.1.11

Accept Connec tion

Receive Data

Send Data

Open TCP

Connection

Data = abc

Data = xyz

The response is returne d to the controller as soon as the data is sent.

Create Socket

Create Socket Response

Instance = 102

OpenConnection

"192.168.1.11?Port=49200"

OpenConnection Response

Write Data = abc

Write Response

Read

Read Response Data = xyz

Typical Sequence of Transactions for a TCP Client

The following diagram shows a typical sequence of socket interface transactions with the Logix 5000 controller that acts as a TCP client. Each transaction between the Logix 5000 controller and the EtherNet/IP module is a message (MSG) instruction.

This example shows the Logix 5000 controller sending data to a device, and then the device sending a response. This sequence of transactions is typical. Depending on the application protocol, the device could instead initiate sending data to the Logix 5000 controller once the connection is open.

Also, each write transaction does not require an application response or acknowledgment. The application protocol determines the exact sequence of application transactions.

10 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Socket Interface Architecture Chapter 1

Controller

EtherNet/IP Module

192.168.1.10

Device

192.168.1.11

Open Connection

Send Data

Receive Data

Open TCP Connection

Port=49100

Data = abc

Data = xyz

The response is returned to the controller as soon as the data is sent.

Create Socket

Port = 49100

Create Socket Response

Instance = 102

AcceptConnection

Writ e

Data = xyz

Write Response

Read

Read Response

Data = abc

AcceptConnection Response

Typical Sequence of Transactions for a TCP Server

The following diagram shows a typical sequence of socket interface transactions with the Logix 5000 controller as a TCP server. Each transaction between the Logix 5000 controller and EtherNet/IP module is a MSG instruction.

The following is a typical sequence of transactions. The exact sequence of sending and receiving data depends on the application protocol.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 11

Chapter 1 Socket Interface Architecture

Controller

EtherNet/IP Module

192.168.1.10

Device

192.168.1.11

Create Socket

Port=49100

Create Socket Response

Instance = 102

Writ e

192.168.1.11?Port=49200 Data = abc

Write Response

Read

Read Response

192.168.1.11?Port=49200 Data = xyz

Send Data to

192.168.1.10, Port 49100

Receive Data from Port 49200

Data = abc

Data = xyz

The response is returned to the controller as soon as the data is sent.

Typical Sequence of Transactions for UDP without OpenConnection

The following diagram shows a typical sequence of socket interface transactions for UDP communication without using the OpenConnection service to specify the destination address. In this case, the Logix 5000 controller specifies the destination for each datagram and receives the address from the sender along with each datagram it receives. Each transaction between the Logix 5000 controller and the EtherNet/IP module is a MSG instruction.

This example shows the Logix 5000 controller sending data to a device, and then the device sending a response. This sequence of transactions is atypical. Depending on the application protocol, the device could instead initiate sending data to the Logix 5000 controller. Also, each Write transaction does not require an application response or acknowledgment. The application protocol determines the exact sequence of application transactions.

12 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Socket Interface Architecture Chapter 1

Controller

EtherNet/IP Module

192.168.1.10

Device

192.168.1.11

Create Socket

Port=49100

Create Socket Response

Instance = 102

Open Connection

192.168.1.11?Port=49200

Open Connection Response

Read

Read Response

192.168.1.11?Port=49200 Data = xyz

Writ e

Data = abc

Write Response

Data = abc

Data = xyz

The response is returned to the controll er as soon as the data is sent.

Send Data To

192.168.1.10, Port 49100

Receive Data from Port 49200

Typical Sequence of Transactions for UDP with OpenConnection

The following diagram shows a typical sequence of socket interface transactions for UDP communication when using the OpenConnection service to specify the destination address. Each transaction between the Logix 5000 controller and the EtherNet/IP module is a MSG instruction.

The following is a typical sequence of transactions. The exact sequence of sending and receiving data depends on the application protocol.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 13

Chapter 1 Socket Interface Architecture

Communicate with the Socket Object Via a MSG Instruction

In a Logix 5000 controller program, use a CIP™ Generic MSG instruction to request socket services.

IMPORTANT The MSG instruction must be sent to the EtherNet/IP module via backplane.

On the Configuration tab, configure the parameters as described in Ta b l e 1

Table 1 - Configuration Tab

Field Description

Message Type Choose CIP Generic.

Service Type Choose a socket service type. The software automatically completes the Service Code and Class

Service Code Type the unique service code that corresponds to the socket service you chose in the Service Type

Class Type 342 (hexadecimal) for the socket object.

Instance Type one of these values:

Attribute Type an attribute value only when getting or setting an attribute, but not when using other

Source Element Choose the tag that contains the request parameters for the socket service. To define the request

Source Length Enter the length of the source element.

Destination Element

fields. Choose Get Attributes Single or Set Attributes Single when getting or setting a Socket Object

attribute. For more information, see Access Socket Attributes on page 45

field.

• 0 for Socket Create, Delete All Sockets, and ClearLog services

• Instance number that is returned by Socket Create for other services Use a relay ladder instruction or Structured Text statement to move the returned instance

number from a Socket Create service into the .Instance member of a MSG instruction.

services.

parameters, create a user-defined data type for the tag.

Choose the tag that contains the response data that is returned by the socket service. To define the response data, create a user-defined data type for the tag.

14 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Socket Interface Architecture Chapter 1

On the Communication tab, configure the parameters that are described in

Ta b l e 2

IMPORTANT If you are using the front Ethernet port on a controller, you must use

unconnected MSG instructions.

Table 2 - Communication Tab

Field Description

Path Enter the communication path to the EtherNet/IP module. The module must be accesse d via

Large Connection • When using the controller’s built in Ethernet port, large messages are supported by

the backplane; you cannot access the module via the Ethernet port.

• For all controllers and communication modules, the path is 1, x. Where x is the slot number of the communication module, or the slot number of a ControlLogix 5580 controller if the front Ethernet port is used.

• For all supported CompactLogix controllers, the slot is 0.

• For all CompactLogix 5370, CompactLogix 5380, Compact GuardLogix 5380, CompactLogix 5480, ControlLogix 5580, and GuardLogix 5580 controllers with version

28.11 or later, you can also use a path of ‘THIS’.

default (they are also unconnected messages).

• When using an Ethernet module through the backplane, the Connected checkbox and the Large Connection checkbox must be selected to use large messages. A large connection is only available with connected MSG instructions. For information about how to use the Connected or Cache Connections options, refer to the Logix 5000 Controllers Messages Programming Manual, publication 1756-PM012

• IMPORTANT: To use controller memory efficiently, use large connections only for ReadSocket or WriteSocket services that require more than the standard connection size, as shown in Tab le 3.

The maximum amount of data you can send or receive depends on how you configure the MSG instruction, as shown in Ta b l e 3

. The size of the data

excludes the parameters in the ReadSocket and WriteSocket services.

Table 3 - Maximum Packet Sizes

Service Unconnected Size Standard Connection Size Large Connection Size

ReadSocket 484 bytes 484 bytes 3984 bytes

WriteSocket 462 bytes 472 bytes 3972 bytes

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 15

Chapter 1 Socket Interface Architecture

If a MSG requests more than the maximum packet size (standard or large), the module can return a failure status and the MSG instruction can set the .ER bit:

• For TCP sockets, if the application data is larger than the maximum size, you can issue multiple ReadSocket or WriteSocket services to receive or send the entire application message.

• For UDP sockets, the size of application data cannot exceed the maximum sizes for the ReadSocket and WriteSocket services.

Service Timeouts

MSG Instruction Timeouts

You must specify a timeout parameter in milliseconds for any service that does not always complete immediately, such as OpenConnection, AcceptConnection, ReadSocket, and WriteSocket services. The timeout tells the socket object the maximum amount of time to wait when attempting to complete the service. While waiting for the service to complete, the MSG instruction is enabled.

If the requested service does not complete before the timeout period expires, the socket object returns a response to the service request. See the service descriptions in Chapter 2

IMPORTANT Make the value of the service timeout parameter is shorter than the MSG

instruction timeout. Otherwise, application data could be lost.

The default MSG instruction timeout is 30 seconds. The maximum MSG timeout is approximately 35 minutes. Specify the MSG instruction timeout by setting the appropriate member of the MSG tag:

• If the MSG is unconnected, set the UnconnectedTimeout member.

• If the MSG is connected, set the ConnectionRate and TimeoutMultiplier member.

for the content of the response.

The MSG timeout is determined by multiplying the ConnectionRate by the TimeoutMultiplier. A TimeoutMultiplier of 0 corresponds to multiplier of 4, 1 corresponds to multiplier of 8, and so on.

16 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Socket Interface Architecture Chapter 1

Socket Instance Timeouts

Each socket instance has an inactivity timeout with a default of 5 minutes. If a socket instance receives no service requests for the amount of time that is specified by the inactivity timeout, the socket instance is deleted. If you then try to use the socket instance, the MSG instruction receives the error class or instance not supported.

You can change the timeout by setting the inactivity time-out attribute via the Set Attribute service. See Socket Instance Attributes on page 47

If you put the controller in Program mode and then back into Run mode before existing socket instances time out, you can receive errors when the program tries to create socket instances. Eventually the socket instances time out and you can create more instances.

IMPORTANT Make sure that the inactivity timeout is longer than the longest interval

between socket operations. If the inactivity timeout is too short, socket instances can time out and result in MSG instruction errors.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 17

Chapter 1 Socket Interface Architecture

Disable the Socket Object With a MSG Instruction

The socket object is enabled by default. You can use a CIP Generic MSG instruction to disable the socket object.

After you disable the socket object:

• All object-specific services and all instance attributes are unavailable for writing and reading. The Object Enable attribute is read-only.

• TCP/IP Socket Object is disabled, and a factory reset is needed to enable it again.

•

IMPORTANT The MSG instruction must be sent to the EtherNet/IP module via backplane.

On the Configuration tab, configure the parameters as described in Ta b l e 1 .

Table 4 - Configuration Tab

Field Description

Message Type Choose CIP Generic.

Service Type Choose Set Attributes Single.

Service Code 10 (hex)

Class 342 (hex)

Instance 0

Attribute 9 (hex)

Source Element Choose the SINT tag that contains the value of zero.

Source Length 1

Destination Element

Not required.

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Socket Interface Architecture Chapter 1

On the Communication tab, configure the parameters that are described in

Ta b l e 2

IMPORTANT If you are using the front Ethernet port on a controller, you must use

unconnected MSG instructions.

Table 5 - Communication Tab

Field Description

Path Enter the communication path to the EtherNet/IP module. The module must be accesse d via

the backplane; you cannot access the module via the Ethernet port.

• For all supported CompactLogix controllers, the slot is 0.

• For all CompactLogix 5370, CompactLogix 5380, Compact GuardLogix 5380, CompactLogix 5480, ControlLogix 5580, and GuardLogix 5580 controllers with version

28.11 or later, you can also use a path of ‘THIS’.

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Chapter 1 Socket Interface Architecture

Programming Considerations

Observe these programming considerations.

TCP Connection Loss

Your application program can encounter conditions that result in TCP connection loss. For example, a network cable can be unplugged, or a target device can be turned off.

Your application program detects the loss of TCP connections and handles those events appropriately. You can detect connection loss when one of the following occurs:

• The ReadSocket service returns with an error.

• The WriteSocket service returns an extended error code other than 16#0000_0046. See Error Codes for Socket Services on page 51

Depending on the application, try these actions:

• Try to re-establish the connection, such as in the case of a client connection.

• Wait for another incoming connection to be established, such as in the case of a server connection.

If you want to re-establish communication with the other device, complete these actions:

• Delete the socket instance for the lost connection.

• If the connection is a client connection, create a socket instance and issue an OpenConnection service to the target device.

• If the connection is a server connection, issue an AcceptConnection service to wait for another connection from the remote device.

IMPORTANT User code must manage messages so that only one message to a socket

instance is active at a time. For example, the read and write socket instructions for a given socket should be interlocked so that only one executes at a time. This is on a per socket basis.

ControlLogix Enhanced Redundancy

IMPORTANT Socket instances that are created in EtherNet/IP modules are not

crossloaded in an enhanced redundancy system.

If your application uses sockets in an enhanced redundancy system, your application program must manage switchovers in these ways:

• After a switchover, socket instances in the EtherNet/IP module in the old primary chassis must be recreated in the EtherNet/IP module in the new primary chassis via controller logic.

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Socket Interface Architecture Chapter 1

• Sockets that are connected outside of the enhanced redundancy system must recognize that communication is lost with socket instances in the EtherNet/IP module in the old primary chassis after a switchover. A change in IP address of the EtherNet/IP module after a switchover causes loss of communication. See TCP Connection Loss on page 20

• Although socket instances in the EtherNet/IP module in the old primary chassis are automatically deleted once their inactivity timeout expires, it is possible that a second switchover can occur before the timeout expires. To be sure that these non-functioning socket instances are deleted before a second switchover, your application program can issue a message to delete all sockets in the event of a switchover before creating functioning socket instances.

To learn more about enhanced redundancy systems, refer to the ControlLogix Enhanced Redundancy System User Manual, publication 1756-UM535

EtherNet/IP Module Reset

If the EtherNet/IP module is reset, for example by cycling power or with removal and insertion under power (RIUP), all socket instances are lost.

If you create socket instances while MSG instructions are still using the old instance numbers, the new instance numbers can match the old instance numbers. In this situation, your old MSG instructions can succeed but could not be communicating with the correct remote device.

Handle this situation by monitoring the status of the EtherNet/IP module via a GSV instruction. If you lose communication with the EtherNet/IP module, the Logix 5000 program reinitializes its socket communication.

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Chapter 1 Socket Interface Architecture

Change Controller Mode between Run and Program

If the Logix 5000 controller transitions from Run mode to Program mode while socket requests are active, the transition does not complete until all outstanding MSG requests complete or time out. If you have long time-out values, you can experience an unexpectedly long time for the Run-to-Program transition to complete.

Alleviate long transition times by appropriately setting the time-out parameter for the socket services. In the Logix 5000 program, you can also set the .TO bit for any outstanding socket-related MSG instruction. This causes the MSG instruction to time out and set the .ER bit.

If the controller transitions from Run mode to Program mode, then back to Run mode again, previous socket instances can still exist on the EtherNet/IP module. The previous socket instances time out eventually. Depending on the number of sockets you need, your program can encounter errors during RunProgram-Run transitions because all available socket instances are in use.

To alleviate this situation, follow this procedure:

1. Wait for all socket instances to time out before putting the controller in Run mode.

2. When the Logix 5000 program starts, use the DeleteAllSockets service to delete any previous instances.

The DeleteAllSockets service deletes all socket instances, not just those instances that are created by the controller that calls the service.

Application Messages and TCP

A TCP connection is a byte stream between two application entities. The application protocol determines the message formats. Messages can be fixed size or variable size.

If an application sends variable size messages, a common strategy is to first send a fixed-size header that contains the size of the message followed by the message. The receiving device can first issue a ReadSocket service of the fixed size header to determine the remaining size, and then issue a subsequent ReadSocket service to receive the remaining data.

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Socket Interface Architecture Chapter 1

/* copy the message we just read */

COP (ReadResponse.Buf[0], ReadBuf[CurrentLen],

ReadResponse.BufLen);

CurrentLen := CurrentLen + ReadResponse.BufLen;

/* do we need to read more data get a complete message? */

if (CurrentLen < ApplicationMsgLen) then

/* issue another read */

ReadParams.BufLen := ApplicationMsgLen - CurrentLen;

MSG (ReadMSG0);

end_if;

Application Messages and Inhibited Modules

Unlike I/O connected via an EtherNet/IP module, communication via messaging to socket instances can continue when a module is inhibited. If you want to stop socket communication when a module is inhibited, your application code must detect the status of the module and take the appropriate action.

Partial Reads

It is possible for a read service to return a BufLen that is less than the requested amount of data. For example, your program can request 100 bytes of data. Because TCP is a byte stream and not a datagram protocol, you can receive less than 100 bytes when the read service returns.

Depending on the application protocol, issue additional read requests to receive all of the data. If the application protocol dictates that all messages are 100 bytes, then you must issue additional read requests until you receive 100 bytes. If the application protocol uses variable size messages, your program needs additional logic to handle variable message sizes as defined by the application protocol.

When issuing multiple read requests, be careful to adjust the destination tag that receives the data so that data is not overwritten.

If the read request times out before any data is received, a BufLen of 0 is returned with success (0) status.

This fragment of Structured Text logic shows an example of handling a partial read request.

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Chapter 1 Socket Interface Architecture

if (WriteMSG0.ER) then

/* write failed. if the extended error code was 16#0000_0046, then it means less than the requested byte were sent. */

if (WriteMSG0.EXERR = 70) then

/* need to issue another write, with the data that was not sent */

SentLen := WriteResponse; /* here's what was sent */

/* adjust the size */

WriteParams.BufLen := WriteParams.BufLen - SentLen;

/* copy remaining data to send to MSG buffer */

COP (WriteBuf[SentLen], WriteParams.Buf[0],

WriteParams.BufLen);

/* BufLen = Timeout + Sockaddr + data length */

WriteMSG0.REQ_LEN := 4 + 12 + WriteParams.BufLen;

MSG (WriteMSG0);

end_if;

Partial Writes

Although uncommon, your program can need to handle a situation where a write service is unable to send all specified bytes. Such a situation can occur if the write service is called multiple times before the target application can receive the data.

If the write service is not able to send the requested data, your program issues subsequent writes to send the remaining data. Your program also adjusts the source tag, so that old data is not sent.

If the number of bytes written is less than requested, an extended error is returned, and the actual length of the data sent.

This fragment of Structured Text logic shows an example of handling a partial write service.

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Socket Interface Architecture Chapter 1

Performance Considerations

The socket interface enables a Logix 5000 controller to communicate via an EtherNet/IP module with Ethernet devices that do not support the EtherNet/IP application protocol, such as barcode scanners, RFID readers, or other standard Ethernet devices. The socket interface, via messaging, is not well suited for real-time control as communication with this method is not scheduled or deterministic.

There are various factors that can affect the performance of the socket interface. For examples of some of the factors to consider, see the Knowledgebase Article 1756-EWEB Performance

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Chapter 1 Socket Interface Architecture

Notes:

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Socket Object Services

Top ic Pa ge

Socket Create 28

OpenConnection 30

AcceptConnection 32

ReadSocket 34

WriteSocket 36

DeleteSocket 38

DeleteAllSockets 39

ClearLog 40

JoinMulticastAddress 41

DropMulticastAddress 42

Chapter 2

For a socket object, application data has no inherent byte order. The service receives data in the same byte order as it is sent. However, Logix 5000™ controllers store data in CIP™ byte order (little-endian). For example, if you issue a write service with one DINT, that DINT is sent over a TCP connection or in a UDP datagram in CIP byte order. If you issue a read service and your destination tag for the response contains a DINT, the Logix 5000 controller assumes that the incoming data is in CIP byte order. Depending on the native byte order of the application that you are communicating with, you may need to convert the byte order in your Logix 5000 program or in the application.

To check your MSG configuration in the Studio 5000 Logix Designer® application, choose a service type from the Service Type pull-down menu on the Configuration tab of the Message Configuration dialog box. The software automatically completes the Service Code and Class fields.

With RSLogix 5000® software, version 15 and earlier, choose Custom from the Service Type pull-down menu and manually complete the Service Code and Class fields.

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Chapter 2 Socket Object Services

Parame ter Value

Service Type Socket Create

Service Code 4b

Class 342

Instance 0

Attribute 0

Socket Create

The Socket Create service creates an instance of the socket object. The service returns an instance number that you use in the subsequent socket operations. Call the Socket Create service with instance 0 (Socket object class).

MSG Source Element

Choose a tag with a user-defined data type. Use the information in Ta b l e 6 to define the data type.

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Table 6 - Data Type for Socket Create Source Element

Member Name Data Type Description

Type DINT Specify one of these values:

• 1 for TCP

• 2 for UDP

Addr structure A user-defined structure that specifies the address for the socket.

Family INT Specify the address family. Must be 2.

Port INT Specify the local port number on which an application listens and receives. If you

want a port randomly assigned, use port 0.

Addr DINT Specify an IP address. Typically, set to 0 (any address) for a CompactLogix™ 5370,

CompactLogix 5380, Compact GuardLogix® 5380, CompactLogix 5480, ControlLogix® 5580, GuardLogix 5580 controller in Linear/DLR mode.

For CompactLogix 5380, Compact GuardLogix 5380, and CompactLogix 5480 controllers in Dual-IP mode, the IP address must be set in HEX format with 1 byte per octet. See Knowledgebase Article 5380 Ethernet Socket Errors and Path

Information.

Socket Object Services Chapter 2

MSG Source Length

Specify the size of the user-defined structure for the source element. In this example, CreateParams is 12 bytes.

MSG Destination Element

The MSG instruction returns the instance number of the socket it created to the destination element. Specify a DINT tag.

Considerations

Use the instance that is returned by the Socket Create service on subsequent service requests.

Use a MOV instruction to move the instance to another MSG tag (the .Instance field).

If you use a local port number that is already in use by the EtherNet/IP™ module, you receive extended error code 16#0000_0030. Avoid using commonly used ports.

When a CompactLogix 5380, Compact GuardLogix 5380, and CompactLogix 5480 controller operates in Dual-IP mode, the default IP address for use with a Socket_Create service type is 0.0.0.0.

• If you use 0.0.0.0, IP communication that the Socket Object instance initiates follows the same routing rules as DNS request routing rules described in these publications:

– CompactLogix 5380 and Compact GuardLogix 5380 Controllers

User Manual, publication 5069-UM001

– CompactLogix 5480 Controllers User Manual,

publication 5069-UM002

• If you use the IP address of port A1 instead of 0.0.0.0, IP packets can only go to the port A1 subnet or via its default gateway.

• If you use the IP address of port A2 instead of 0.0.0.0, IP packets can go only to port A2 subnet or via its default gateway.

• If you use the IP address of port B1 instead of 0.0.0.0, IP packets can only go to the port B1subnet or via its default gateway.

• If you use an IP address other than the port A1 or A2 IP addresses or

0.0.0.0, the Create_Socket_Service request is rejected.

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Chapter 2 Socket Object Services

Parameter Val ue

Service Type OpenConnection

Service Code 4c

Class 342

Instance from Socket Create

Attribute 0

OpenConnection

The OpenConnection service does one of the following:

• Opens a TCP connection with the specified destination address

• For UDP, associates a destination IP address and port number with the specified socket

MSG Source Element

Choose a tag with a user-defined data type. Use the information in Ta b l e 7 to define the data type.

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Table 7 - Data Type for OpenConnection Source Element

Member Name Data Type Description

Timeout DINT Specify the timeout in milliseconds.

DestAddr STRING Specify an array of characters (maximum of 64) to define the destination of

the connection. You can specify either Hostname or IP address.

• Hostname?port=xxxzaz

• IPAddr?port=xxx For example, to specify an IP address, enter 10.88.81.10?port=2813

.LEN DINT The length of the destination address.

.DATA SINT array The array that contains the destination address.

The MSG instruction that issues the OpenConnection service has a source length of 8 (Timeout + AddrLen) plus the number of characters in the destination address.

Socket Object Services Chapter 2

MSG Source Length

Specify 8 bytes (Timeout + AddrLen) + number of characters in the destination address.

MSG Destination Element

Not used. The MSG instruction does not return any data.

Considerations

In some cases, the OpenConnection service can return before the timeout period without creating a TCP connection. For example, if the destination device is running, but is not listening for connections on the specified port number, the OpenConnection service returns with an error before the timeout period.

For UDP, the information you must specify depends on whether you use the OpenConnection service:

• If you use the OpenConnection service, you do not have to specify the IP address and port number each time you send data. If you do not specify an IP address and port number, you can receive data only from the previously specified IP address and port number until you call the OpenConnection service to specify another IP address and port number.

•If you do not use the OpenConnection service, you must specify the destination address each time you call the WriteSocket service to send data. When you call the ReadSocket service, you receive the data and the address of the sender. You can then use the address of the sender to send a response via the WriteSocket service.

If you call the OpenConnection service on a UDP socket with an AddrLen of 0, this removes the association with the destination address.

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Chapter 2 Socket Object Services

Parame ter Value

Service Type AcceptConnection

Service Code 50

Class 342

Instance from Socket Create

Attribute 0

AcceptConnection

The AcceptConnection service accepts a TCP connection request from a remote destination. Before calling the AcceptConnection service, call the Socket Create service and specify the local port number that accepts the connection. When the AcceptConnection service completes, it returns a socket instance that you use for sending and receiving data on the newly created connection.

The AcceptConnection service is not valid for UDP sockets.

MSG Source Element

32 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Choose a DINT tag to contain the timeout in milliseconds.

MSG Source Length

Specify 4 bytes (Timeout).

Socket Object Services Chapter 2

MSG Destination Element

Choose a tag with a user-defined data type. Use the information in Ta b l e 8 to define the data type.

Table 8 - Data Type for AcceptConnection Destination Element

Member Name Data Type Description

Instance DINT Contains the instance for this service. Use this Inst ance on subsequent Read

Addr structure A user- defined structure that contains the address for the socket.

Family INT Contains the address family. Must be 2.

Port INT Contains a remote port number.

Addr DINT Contains a remote IP address.

and Write services for this connection. IMPORTANT: Copy this Instance number to Read and Write Messages

Considerations

Create a separate socket instance by using the Socket Create service for each port number that accepts connections. After you create socket instances, call the AcceptConnection service to wait for an incoming connection request. You can accept connections on the same port number. Each call to the AcceptConnection service returns a different instance number to use when reading and writing data.

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Chapter 2 Socket Object Services

Parame ter Value

Service Type ReadSo cket

Service Code 4d

Class 342

Instance See Instance

Attribute 0

ReadSocket

The ReadSocket service reads data on a socket. You specify the number of bytes to receive. The service returns the number of bytes received.

For TCP, the ReadSocket service returns when any data is received, up to the requested number of bytes. If no data is received before the timeout period, the service returns a status of success by setting a message instruction Done Bit (.DN) and a BufLen of 0. The service can return fewer bytes than were requested. Your application may need to issue multiple read requests to receive an entire application message.

For UDP, the ReadSocket service completes when a datagram is available.

Instance

This service uses the instance that is returned from the CreateConnection service. However, when accepting a connection via the AcceptConnection service, use the instance that is returned from this AcceptConnection service as the ReadSocket instance.

MSG Source Element

Choose a tag with a user-defined data type. Use the information in Ta b l e 9 to define the data type.

34 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Table 9 - Data Type for ReadSocket Source Element

Member Name Data Type Description

Timeout DINT Specify the timeout in milliseconds.

BufLen DINT Specify the number of bytes of data to receive.

Socket Object Services Chapter 2

MSG Source Length

Specify 8 bytes (Timeout + BufLen).

MSG Destination Element

Choose a tag with a user-defined data type. Use the information in Ta b l e 1 0 to define the data type.

Table 10 - Data Type for ReadSocket Destination Element

Member Name Data Type Description

FromAddr structure A user-defined structure that can contain the address of the device that s ends

Family INT Contains the address family for UDP. Must be 2.

Port INT Contains the remote port number for UDP. The remote device uses this port for

Addr DINT Contains the remote IP address for UDP

BufLen DINT Contains the number of bytes of data received.

Buf SINT array Contains the data.

UDP data. This structure is populated from the end device. For TCP or UDP with OpenConnection, this structure is not used and contains all

zeros. The TCP connection conveys all remote address information.

sending. 0 is an invalid port number for UDP.

This number must be large enough to contain the maximum amount of data expected. For a standard connection, the maximum is SINT[484]; for a large connection the maximum is SINT [3984].

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Chapter 2 Socket Object Services

Parame ter Val ue

Service Type WriteSocket

Service Code 4e

Class 342

Instance See Instance

Attribute 0

WriteSocket

The WriteSocket service sends data on a socket. You specify the number of bytes to send. The service attempts to send the requested number of bytes and returns the number of bytes sent.

Instance

MSG Source Element

Choose a tag with a user-defined data type. Use the information in Table 11 on

page 37 to define the data type.

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Socket Object Services Chapter 2

Table 11 - Data Type for WriteSocket Source Element

Member Name Data Type Description

Timeout DINT Specify the timeout in milliseconds.

ToAddr structure A user-defined structure that contains the address to which to write UDP data.

For TCP or UDP with OpenConnection, this struc ture is not used and contains all zeros. The TCP connection conveys all required remote address information.

Family INT Specify the address family. Must be 2 for UDP.

Port INT Specify the remote port number for UDP. This is the port that the remote device

Addr DINT Specify the remote IP address for UDP.

BufLen DINT Specify the number of bytes of data to write.

Buf SINT array Contains the data.

uses for receiving. 0 is an invalid port number for UDP.

0.0.0.0 is an invalid IP address for UDP.

This number must be large enough to contain the maximum amount of data expected. For a standard connection, the maximum is SINT[472]; for a large connection the maximum is SINT [3972].

MSG Source Length

Specify 16 bytes (Timeout + Addr + BufLen) + number of bytes to write.

MSG Destination Element

The MSG instruction returns the number of bytes that were written. Choose a DINT tag.

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Chapter 2 Socket Object Services

Parame ter Va lue

Service Type DeleteSocket

Service Code 4f

Class 342

Instance from Socket Create

Attribu te 0

DeleteSocket

The DeleteSocket service deletes a socket instance. For a TCP connection, the DeleteSocket service also closes the connection before it deletes the instance.

MSG Source Element

Not used.

MSG Source Length

Specify 0 bytes.

MSG Destination Element

Not used.

Considerations

Delete a socket instance if it is no longer needed. If unused instances are not deleted and you continue to create additional instances, you can exceed the maximum number of instances.

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Socket Object Services Chapter 2

Parame ter Valu e

Service Type Custom

Service Code 51

Class 342

Instance 0

Attribu te 0

DeleteAllSockets

The DeleteAllSockets service deletes all currently created socket instances. For TCP, the DeleteAllSockets service also closes all connections before it deletes the instances.

Choose Custom for the service type. DeleteAllSockets is not an available option from the Service Type pull-down menu.

MSG Source Element

Not used.

MSG Source Length

Specify 0 bytes.

MSG Destination Element

Not used.

Considerations

Call the DeleteAllSockets service with instance 0.

IMPORTANT Be careful when using the DeleteAllSockets service when there are multiple

controllers using the socket interface of the EtherNet/IP module. The service deletes all socket instances that are created by all controllers, not just the controller that calls the service.

Use the DeleteAllSockets service as the first operation when the program first begins to operate.

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Chapter 2 Socket Object Services

Parame ter Valu e

Service Type Custom

Service Code 52

Class 342

Instance 0

Attribu te 0

ClearLog

The ClearLog service clears the debug log on the TCP/IP Socket Object webpage. This service does not change the logging options.

IMPORTANT The TCP/IP Socket Object webpage is not visible on ControlLogix 5580,

GuardLogix 5580, CompactLogix 5380, Compact GuardLogix 5380, and

CompactLogix 5480 controllers.

Choose Custom for the service type. ClearLog is not an available option from the Service Type pull-down menu.

MSG Source Element

Not used.

MSG Source Length

Specify 0 bytes.

MSG Destination Element

Not used.

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Socket Object Services Chapter 2

Parame ter Valu e

Service Type Custom

Service Code 53

Class 342

Instance from Socket Create

Attribu te 0

JoinMulticastAddress

Joining a multicast group lets a socket receive multicast data. When a join is executed, it sends an IGMP membership packet and enables the hardware filters to receive the multicast data. A specific address can be joined only once. Subsequent joins receive an error message until the multicast address is dropped. Multicast joins are system wide. Two sockets cannot join the same multicast address simultaneously. When the socket that the join was executed on is deleted, the multicast address is dropped. Each socket can join one or more multicast groups.

Choose Custom for the service type. JoinMulticastAddress is not an available option from the Service Type pull-down menu.

MSG Source Element

Choose a tag with a user-defined data type. Use the information in Ta b l e 1 2 to define the data type.

Populate the Join_Source_Data.Addr field with a multicast IP address in hexadecimal format. The value must be a hexadecimal representation of the IP address. For example, for address 239.1.2.100, enter 16#EF010264.

Table 12 - Data Type for JoinMulticastAddress Source Element

Member Name Data Type Description

SocketsAddr structure A user-defined structure that specifies the multicast address to join.

Family INT Specify the address family. Must be 2.

Port INT Not used. The port is determined when the socket is created.

Addr DINT Specify the multicast IP address to receive from.

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Chapter 2 Socket Object Services

Parame ter Value

Service Type Custom

Service Code 54

Class 342

Instance from Socket Create

Attribute 0

MSG Source Length

Specify 8 bytes.

MSG Destination Element

Not used.

DropMulticastAddress

Dropping a multicast address disables a socket from receiving multicast data. When a drop is executed, it sends an IGMP leave group packet and disables the hardware filters from receiving the multicast data.

Choose Custom for the service type. DropMulticastAddress is not an available option from the Service Type pull-down menu.

MSG Source Element

Choose a tag with a user-defined data type. Use the information in Table 13 on

page 43 to define the data type.

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Socket Object Services Chapter 2

Table 13 - Data Type for DropMulticast Address Source Element

Member Name Data Type Description

SocketsAddr structure A user-defined structure that specifies the multicast address to drop.

Family INT Specify the address family. Must be 2.

Port INT Not used. The port is determined when the socket is created.

Addr DINT Specify the multicast IP address to drop.

MSG Source Length

Specify 8 bytes.

MSG Destination Element

Not used.

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Chapter 2 Socket Object Services

Notes:

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Socket Attributes

Top ic Pag e

Access S ocket Attribu tes 45

Socket Class Attributes 46

Socket Instance Attributes 47

Chapter 3

Access Socket Attributes

You access socket attributes by configuring a CIP™ Generic MSG instruction to get or set the specific attribute:

• To change an attribute value for a socket, choose Set Attribute Single from the Service Type pull-down menu.

• To get a socket value, choose Get Attribute Single from the Service Type pull-down menu.

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Chapter 3 Socket Attributes

Some socket attributes apply to all sockets, and some apply to specific socket instances:

• For information about all sockets, type 0 in the Instance field. See Socket

Class Attributes.

• For information about a specific socket instance, type the specific socket instance number in the Instance field. A Socket Create or AcceptConnection service returns the instance number. See Socket

Instance Attributes on page 47.

Socket Class Attributes

Class attributes apply to the socket object, not to specific socket instances. When you get or set a Class attribute, set the instance to 0

Table 14 - .Socket Class Attributes

Class Attribute

1 Revision INT Get Object revision.

2 Max Instance INT Get Largest socket instance number currently created.

3 Number of Instances INT Get Number of socket instances currently created.

8Log Enable

9Object EnableSINTGet

(1) The Socket Object webpage is not visible on ControlLogix® 5580, GuardLogix® 5580, CompactLogix™ 5380, Compact GuardLogix

Name Data

(1)

5380, and CompactLogix 5480 controllers.

Type

DINT Get

Access Description

Enable (1) or disable (0) logging to the Socket Object Log webpage.

Set

Each socket service has a corresponding bit:

• If enabled, requests for that service request are logged.

• If disabled, then requests for that service are not logged.

Bit 0: Socket Create requests Bit 1: OpenConnection requests Bit 2: AcceptConnection requests Bit 3: Read requests Bit 4: Write requests Bit 5: DeleteSocket and DeleteAllSockets requests Bit 6: Get / Set Attribute requests Bit 7: Log all service errors

Enable (1) or disable (0) the Socket Object. Default is enabled.

Set

If you use the Get Attributes All service to get class attributes, the response contains all class attributes in Ta b l e 1 4

in the order shown with a total size of

10 bytes.

If you use the Set Attributes All service to set class attributes, the request contains only the Log Enable class attribute.

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Socket Attributes Chapter 3

Socket Instance Attributes

The socket object provides a number of instance attributes that apply to specific socket instances. To get or set an instance attribute, specify a valid instance number.

Table 15 - Socket Instance Attributes

Instance Attribute

1 (16#01) LocalAddr Struct SockAddr Get Local address for the socket.

2 (16#02) RemoteAddr Struct SockAddr Get Remote address for the socket.

3 (16#03) SendBufSize DINT Get

4 (16#04) RecvBufSize DINT Get

5 (16#05) TCPKeepAlive DINT Get

6 (16#06) TCPNoDelay DINT Get

7 (16#07) InactivityTimeout DINT Get

8 (16#08) MulticastTTL DINT Get

9 (16#09) UDPBroadcast DINT Get

10 (16#0A) LingerOnOff DINT Get

Name Data Type Access Description

Size of the socket send buffer (bytes).

Set

Size of the socket receive buffer (bytes).

Set

Enable (1) or disable (0) TCP Keep Alive for the socket.

Set

Enabled by default.

Enable (1) or disable (0) the TCP No Delay behavior. Enabled by default.

Time for the inactivity timeout (default of 5 minutes). If a socket instance receives no service requests for the amount of time that is specified by the inactivity timeout, the socket instance is deleted. If you then try to use the socket instance, the MSG instruction receives the error Class or instance not supported.

Set the TTL value for UDP multicast, transmitted packets.

Enable (1) or disable (0) the ability to transmit broadcast packets on UDP. Disabled by default.

Specifies whether the socket performs an orderly close (1) or an immediate close (0).

Defaults to no linger (immediate close). For TCP sockets, setting linger to 0 results in a TCP RST packet to close the connection. If you set linger to nonzero, then it results in the standard TCP connection close sequence (3way FIN, FIN-ACK, ACK handshake followed by TIME_WAIT).

If you use the Get Attributes All service to get instance attributes, the response contains all attributes in Ta b l e 1 5

in the order that is shown with a total size of

36 bytes.

If you use the Set Attributes All service, the request must include attributes 3, 4, 5, 6 and 7 in that order with a total size of 20 bytes.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 47

Chapter 3 Socket Attributes

Notes:

48 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Troubleshoot Socket Applications

Top ic Pag e

Diagnostic Webpages 49

Error Codes for Socket Services 51

Knowledgebase Articles 52

Chapter 4

Diagnostic Webpages

To help debug and troubleshoot applications, the socket interface provides a set of webpages:

IMPORTANT The Socket Object webpage is not visible on ControlLogix® 5580,

GuardLogix® 5580, CompactLogix™ 5380, Compact GuardLogix 5380, and CompactLogix 5480 controllers.

• For communication modules and controllers, go to Diagnostics > Advanced Diagnostics > Miscellaneous > System Data > Socket Object.

• For web server modules, go to Diagnostics > Advanced Diagnostics.

Webpage Description

Socket Object Diagnostics Displays information about each instance:

• Instance number

• Socket type—client, server, or listen

• Local and remote ports and IP addresses

• Send and receive buffer sizes

• Socket up time and inactivity time

• Socket state and last error state

Socket Object Attributes Displays attribute settings for each instance

Socket Object Logs Displays a log of ser vice requests with a maximum of 100 log entries:

• Service requests made to the socket object

• Parameters that are passed for each service request

• Whether the service request was a success or failure You can enable or disable logging for some services by using the Log Enable class

attribute. See Socket Class Attributes on page 46

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 49

Chapter 4 Troubleshoot Socket Applications

Debugging Tips

This table describes tips for debugging problems by category.

Category Consideration

EtherNet/IP™ module Make sure the EtherNet/IP module has a valid IP address. Also, if you communicate

with devices on different subnets, configure the EtherNet/IP module with a valid subnet mask and gateway address.

Socket Create service Make sure that the Destination tag is a DINT tag.

After creating the socket with the Socket Create service, make sure that you use the instance number that the service returns in the subsequent socket services you call.

MSG instruction Make sure that the Source Element is of a type that matches the request

parameters for the requested service. Also make sure that the Source Length is the correct length for the service parameters.

There is a limit to the number of active MSG instructions in a Logix 5000™ controller. If a MSG instruction is enabled and exceeds the maximum number of active MSG instructions, the MSG instruction receives an error (.ER bit set).

OpenConnection service Make sure that the Source Length includes the size of the Timeout parameter +

Address Length parameter + the Length of the address itself.

Service Timeout parameter Make sure that the Timeout parameter is sufficient for the service. Also make sure

that the Timeout parameter is less than the MSG instruction timeout. If the timeout is set to 0, the service returns immediately.

TCP protocol A TCP connection is a byte stream with no inherent message boundaries. The

application defines how to interpret message boundaries. For example, the application can use a fixed length for all messages. For a variable-length message, the application can use a fixed-length header that contains the length of the remainder of the message.

Both ends of the TCP connection must agree on the application protocol that is used.

"our program should handle the loss of TCP connections in case they get dropped due to network issues or other reasons.

Ethernet sniffer An Ethernet sniffer is useful to monitor the messages bet ween the EtherNet/IP

module and other devices. You can capture network traffic and create filters to isolate messages between particular devices and particular messages between those devices.

50 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Troubleshoot Socket Applications Chapter 4

Error Codes for Socket Services

If a socket object encounters an error with a service request, the following occurs:

• Socket object returns an error code.

• MSG instruction sets the .ER bit.

• MSG instruction sets error codes in the Error (.ERR) and Extended Error (.EXTERR) fields.

This table describes common error codes. For more a comprehensive list of error codes, see the Knowledgebase Article Logic Sockets Services Error Codes

Error Code Extended Error Code Description

16#0002 Simultaneous execution of Read, Write, or Delete messages.

16#0004 Attempt to access Socket Object via Ethernet port is blocked because of resiliency concerns.

For more information, see the Knowledgebase article, Logix Sockets message error 16#0004.

16#0005 16#0000_0000

or 16#0000_0001

16#0008 ENxT or ENxTR module that is used for socket messages is in a remote chassis that is connected to the controller over the

16#0009 Invalid socket descriptor. To resolve this error, do the following:

16#000b or 16#000c

16#000d Invalid data in Source UDT.

16#0013 or 16#0015

16#0020 The ‘Write’ message instruction Source length is less than 17 bytes. Length must be exactly equal to the buffer length+16.

16#00ff 16#0000_0016

16#0000_0033

16#00ff 16#0000_0030 The address is already in use. This error can occur when multiple Socket Create requests are issued to the same port address.

16#00ff 16#0000_0036 A connection was forced closed by a peer. This error can occur when a remote device closes a connection with a Logix module

16#00ff 16#0000_0039 In Server mode, instance number from Accept Message was not copi ed to Read/Write messages.

16#00ff 16#0000_003d A connection refused by a peer. Possibly peer is out of connections if Logix module closes them without Linger Attribute set.

1. Ethernet module does not have firmware that supports Logix Sockets.

2. The socket instance does not exist. This error can occur in these scenarios: – The socket instance number that is returned by the Socket Create service does not match the instance number in the socket

read or write message. – The socket instance closed due to inactivity. – The DeleteSocket ser vice deleted the socket.

ControlNet® network or is using an older EtherNet/IP module that supports only 478-byte messages. For more information, see the Knowledgebase Article Open Sockets: Message Read/Write error 16#0008 if "Large Connection" option

is enabled.

• Make sure that a valid socket instance exists.

• Make sure that the message source data format and source values are correct.

• For Create messages, make sure that Type and Family is set correctly.

• For UDP Read/Write messages, make sure that Source tag member Family is set to ‘2’.

The Open (Connect) message instruction and Accept message were executed on the same socket. For more information, see the Knowledgebase Article Open Sockets Error codes 16#000b, 16#000c.

The ‘Write’ message instruction Source length must be exactly equal to the buffer length+16. For more information, see the Knowledgebase Article Open Sockets Error code 16#0013 and 16#0015

For Connect messages, make sure that the Destination String address includes ‘?port=xxxx’ similar to 192.168.1.34?port=9100. For more information, see the Knowledgebase Article - 1756-EN2T, 1756-E WEB sockets error 16#0020

Open Sockets (TCP Client) is unable to connect to a third-party device (Slave). The device reports WIN=0 and the 1756-EN2T module immediately closes the connection. For more information, see the Knowledgebase Article Open Sockets: Open connection

fails with error 16#0000_0046,16#0000_0016 or 16#0000_0033.

without notifying the module. To resolve this error, delete the socket and then reconnect to the remote device.

For more information, see the Knowledgebase Article Logix Open Sockets Linger Control.

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 51

Chapter 4 Troubleshoot Socket Applications

Error Code Extended Error Code Description

16#00ff 16#0000_0041 A socket operation could not find a route to the remote host. This error typically occurs in these scenarios:

16#00ff 16#0000_0043 The remote device or gateway is not responding.

16#00ff 16#0000_0046 The socket operation timed out. Known reasons include the following:

16#00ff 16#0009_0315 Invalid Path string manually (or programmatically) entered to the MSG.Path string.

16#0001 16#0000_0117 Invalid Path programmatically entered to the MSG.Path string using COP or another string manipulation instruction.

• A remote IP address that is specified in the Message instruction is not on the same subnet as the Logix module. and The IP address of the gateway or router is not specified in the Logix module properties.

• UDP multicasts messages to an unpingable IP address require you to specify a gateway address in the Logix module properties even if a gateway address does not exist or is not required.

For more information, see the Knowledgebase Article 1756-EWEB socket errors 16#0041 and 16#0043

This error can occur if a UDP multicast message is sent to a gateway address that is not specified in the Logix module properties. For more information, see the Knowledgebase Article 1756-EWEB socket errors 16#0041 and 16#0043

1. Connect Service message: – Server IP exists, but port does not. – Server IP and port exist, but it does not accept connec tion on this port. – Service ‘timeout’ value in UDT set to 0 or low value.

The peer device reports WIN=0 and the 1756-EN2T module immediately closes the connection. For more information, see. the Knowledgebase Article Open Sockets: Open connection fails with error 16#0000_0046,16#0000_0016 or 16#0000_0033.

2. Read/Write Service message: – Read and write executed simultaneously.

For more information, see the Knowledgebase Article Open Sockets message Error 16#00FF extended 16#0000_0046.

For more information, see the Knowledgebase Article Sockets Error code 16#0001 Extended Code 16#0000_0117

Knowledgebase Articles

Knowledgebase Article Description

Sample Application for Ethernet module Sockets Feature Sample applications for the 1756-EWEB module and CompactLogix 5380 controllers.

Logic Sockets Services Error Codes

EWEB socket services hints Helpful hints for EWEB socket ser vices.

Summary of Logix Socket Information Summary of major sockets topics and functionality descriptions.

RSLogix 5000® : AOI example for using sockets to read t ime from NTP or SNTP se rver

Example Add On Instructions for Sockets Using sockets in AOIs (Add-on Instructions).

Email with Basic Login Authentication Using Sockets and AOI Using Sockets for Email with Basic Login Authentication

For additional help, see these Knowledgebase Articles:

Descriptions of possible socket error codes.

Add-On Instruction example for using sockets to read time from NTP or SNTP server

52 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Index

AcceptConnection service 30–31 access

Knowledgebase 51 MSG configuration 25 socket attributes 43

application messages

TCP considerations 21 uninhibited module considerations 21

architecture, socket interface

number and type of sockets 10, 11 overview 10 TCP client transactions 12 TCP server transactions 12 UDP communication 13–14

attributes

access via MSG instruction 43 socket class attributes 44 socket instance attributes 45 socket object 47

broadcast 11

change

controller mode 21 socket attribute value 43

class attributes 44 ClearLog service 38 client socket, TCP 10 codes, error 49 communication

socket object 16–18 UDP 13–14

connection loss 19 considerations, programming 19–23 controller mode 21 ControlLogix enhanced redundancy 20 crossload 20

datagram 13, 22, 25, 32 debugging 47–51 DeleteAllSockets service 37 DeleteSocket service 36 diagnostic web pages 47 DropMulticastAddress service 40–41 dropped connection 19

Ethernet sniffer 48 EtherNet/IP module

debug 48 reset 20

instance attributes 45 instance, socket 10 instruction, MSG

socket attributes 43 socket communication 16–18 timeouts 18

interface architecture 10

JoinMulticastAddress service 39–40

Knowledgebase articles 51

listen socket, TCP 10 Logix 5000 controller

as TCP client 12 as TCP server 12

logs, socket object 47

maximum packet size 18 messages

TCP considerations 21 uninhibited module considerations 21

mode, controller 21 module reset 20 MSG configuration 25 MSG instruction

debugging 48 socket attributes 43 socket communication 16–18 timeouts 18

multicast 11

OpenConnection service

about 28–29 debugging 48

enhanced redundancy 20 error codes 49

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 53

packet size 18 partial reads 22 partial writes 22

Index

Program mode 21 programming considerations 19–23 protocol, TCP 48

reads, partial 22 ReadSocket service 32–33 redundancy, enhanced 20 request socket services 16 reset

Ethernet/IP module 20

Run mode 21

sequence of transactions

TCP client 12 TCP server 12 UDP communication 13–14

server socket, TCP 10 Service Timeout parameter 48 service timeouts 18 services

AcceptConnection 30–31 ClearLog 38 DeleteAllSockets 37 DeleteSocket 36 DropMulticastAddress 40–41 JoinMulticastAddress 39–40 OpenConnection 28–29 ReadSocket 32–33 Socket Create 26–27 WriteSocket 34–35

size, packet 18 sniffer, Ethernet 48 socket class attributes 44 Socket Create service

about 26–27 debugging 48

socket instances

attributes 45 crossload 20 timeouts 18 types of 10

socket interface

architecture 10 MSG instructions 16 number and type of sockets 10, 11 programming considerations 19–23 service timeouts 18 TCP client 12 TCP client transactions 12 TCP server 12 TCP server transactions 12 UDP communication 13–14

socket object attributes 47 socket object diagnostics 47 socket object logs 47

socket object services

AcceptConnection 30–31 ClearLog 38 DeleteAllSockets 37 DeleteSocket 36 DropMulticastAddress 40–41 error codes 49 instances 11 JoinMulticastAddress 39–40 OpenConnection 28–29 overview 11, 25 ReadSocket 32–33 Socket Create 26–27 timeouts 18 WriteSocket 34–35

switchover 20

TCP application messages 21 TCP client socket 10 TCP client transactions 12 TCP communication 11, 12 TCP connection loss 19 TCP listen socket 10 TCP protocol 48 TCP server socket 10 TCP server transactions 12 timeout parameter 48 timeouts 18 tips for debugging 48 transaction sequence

TCP client 12 TCP server 12 UDP communication 13–14

troubleshooting

debugging tips 48 diagnostic web pages 47 error codes 49 Knowledgebase articles 51

UDP communication 11, 13–14 UDP socket 10 unicast 11 uninhibited modules

application message considerations 21

web pages, diagnostic 47 writes, partial 22 WriteSocket service 34–35

54 Rockwell Automation Publication ENET-AT002D-EN-P - October 2020

Notes:

EtherNet/IP Socket Interface Application Technique

Rockwell Automation Publication ENET-AT002D-EN-P - October 2020 59

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Publication ENET-AT002D-EN-P - October 2020

Rockwell Automation EtherNet/IP Original Instructions

Specifications and Main Features

Frequently Asked Questions

User Manual

EtherNet/IP Socket Interface

Summary of Changes

Table of Contents

Additional Resources

Socket Interface Architecture

Number and Type of Sockets

Typical Sequence of Transactions for a TCP Client

Typical Sequence of Transactions for a TCP Server

Typical Sequence of Transactions for UDP without OpenConnection

Typical Sequence of Transactions for UDP with OpenConnection

Communicate with the Socket Object Via a MSG Instruction

Service Timeouts

MSG Instruction Timeouts

Socket Instance Timeouts

Disable the Socket Object With a MSG Instruction

Programming Considerations

TCP Connection Loss

ControlLogix Enhanced Redundancy

EtherNet/IP Module Reset

Change Controller Mode between Run and Program

Application Messages and TCP

Application Messages and Inhibited Modules

Partial Reads

Partial Writes

Performance Considerations

Socket Create

MSG Source Element

MSG Source Length

MSG Destination Element

Considerations

OpenConnection

MSG Source Element

MSG Source Length

MSG Destination Element

Considerations

AcceptConnection

MSG Source Element

MSG Source Length

MSG Destination Element

Considerations

ReadSocket

MSG Source Element

MSG Source Length

MSG Destination Element

WriteSocket

MSG Source Element

MSG Source Length

MSG Destination Element

DeleteSocket

MSG Source Element

MSG Source Length

MSG Destination Element

Considerations

DeleteAllSockets

MSG Source Element

MSG Source Length

MSG Destination Element

Considerations

ClearLog

MSG Source Element

MSG Source Length

MSG Destination Element

JoinMulticastAddress

MSG Source Element

MSG Source Length

MSG Destination Element

DropMulticastAddress

MSG Source Element

MSG Source Length

MSG Destination Element

Access Socket Attributes

Socket Class Attributes

Socket Instance Attributes

Diagnostic Webpages

Debugging Tips

Error Codes for Socket Services