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Application Technique
EtherNet/IP Socket Interface
Important User Information
Read this document and the documents listed in the additional resources section about installation, configuration, and operation of this equipment before you install, configure, operate, or maintain this product. Users are required to familiarize themselves with installation and wiring instructions in addition to requirements of all applicable codes, laws, and standards.
Activities including installation, adjustments, putting into service, use, assembly, disassembly, and maintenance are required to be carried out by suitably trained personnel in accordance with applicable code of practice.
If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be impaired.
In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from the use or application of this equipment.
The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or liability for actual use based on the examples and diagrams.
No patent liability is assumed by Rockwell Automation, Inc. with respect to use of information, circuits, equipment, or software described in this manual.
Reproduction of the contents of this manual, in whole or in part, without written permission of Rockwell Automation,
Inc., is prohibited.
Throughout this manual, when necessary, we use notes to make you aware of safety considerations.
WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous environment, which may lead to personal injury or death, property damage, or economic loss.
ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property damage, or economic loss. Attentions help you identify a hazard, avoid a hazard, and recognize the consequence.
IMPORTANT
Identifies information that is critical for successful application and understanding of the product.
Labels may also be on or inside the equipment to provide specific precautions.
SHOCK HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous voltage may be present.
BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may reach dangerous temperatures.
ARC FLASH HAZARD: Labels may be on or inside the equipment, for example, a motor control center, to alert people to potential Arc Flash. Arc Flash will cause severe injury or death. Wear proper Personal Protective Equipment (PPE). Follow ALL
Regulatory requirements for safe work practices and for Personal Protective Equipment (PPE).
Allen-Bradley, Rockwell Software, Rockwell Automation, CompactLogix, ControlLogix, Logix5000, MicroLogix, RSLogix 5000, and TechConnect are trademarks of Rockwell Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.
New and Updated
Information
Summary of Changes
This manual contains new and updated information. Changes throughout this revision are marked by change bars, as shown to the right of this paragraph.
This table contains the changes made to this revision.
Topic
Updated the Additional Resources.
Updated the list of supported modules.
Added Important message to the Socket Interface Architecture section.
Updated instance creation in ReadSocket.
Updated instance creation in WriteSocket.
Updated the list of Error Codes for Socket Services.
Page
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Summary of Changes
Notes:
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Summary of Changes
Table of Contents
Preface
Socket Interface Architecture
Socket Object Services
Chapter 1
Number and Type of Sockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Typical Sequence of Transactions for a TCP Client . . . . . . . . . . . . . 12
Typical Sequence of Transactions for a TCP Server . . . . . . . . . . . . . 12
Communicate with the Socket Object via a MSG Instruction . . . . . . . . 16
ControlLogix Enhanced Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . 20
EtherNet/IP Module Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Change Controller Mode between Run and Program. . . . . . . . . . . . 21
Application Messages and TCP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Application Messages and Uninhibited Modules . . . . . . . . . . . . . . . . 21
Chapter 2
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
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6
Table of Contents
Socket Attributes
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
MSG Destination Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Chapter 3
Chapter 4
Troubleshoot Socket Applications
Index
Rockwell Automation Publication ENET-AT002C-EN-P - September 2014
Additional Resources
Preface
This publication describes the socket interface that you can use to program
MSG instructions to communicate between a Logix5000™ controller via an
EtherNet/IP module and Ethernet devices that do not support the EtherNet/IP application protocol, such as bar code scanners, RFID readers, or other standard
Ethernet devices.
These documents contain additional information concerning related products from Rockwell Automation.
Resource
Ethernet Design Considerations Reference Manual, publication ENET-RM002
Embedded Switch Technology Reference Architectures
Reference Manual, publication ENET-RM003
EtherNet/IP Network Configuration User Manual, publication ENET-UM001
Industrial Automation Wiring and Grounding Guidelines, publication 1770-4.1
Product Certifications website, http://www.ab.com
Description
Provides a general description of the EtherNet/IP protocol and how to use an EtherNet/IP network.
Provides design recommendations for connecting device-level topologies to larger, switch networks comprised of Layer 2 access switches.
Describes how you can use EtherNet/IP communication modules with your Logix5000 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.
You can view or download publications at http:/www.rockwellautomation.com/literature/ . To order paper copies of technical documentation, contact your local Allen-Bradley distributor or
Rockwell Automation sales representative.
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Preface
Notes:
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Chapter
1
Socket Interface Architecture
Topic
Communicate with the Socket Object via a MSG Instruction
Page
The socket interface lets you use a Logix5000 controller to communicate via an
EtherNet/IP module with Ethernet devices, such as bar code scanners, RFID readers, or other standard Ethernet devices, that do not support the EtherNet/IP application protocol.
Socket services are available with these modules:
• 1756-EN2xx ControlLogix® EtherNet/IP communication modules, firmware version 5.007 or later
• 1756-EWEB ControlLogix EtherNet/IP web server module, firmware version 4.006 or later
• 1768-EWEB CompactLogix™ EtherNet/IP web server module, firmware version 1.002 or later
• 1769-L30ER, 1769-L30ERM, 1769-L30ER-NSE, 1769-L33ER,
1769-L33ERM, and 1769-L36ERM CompactLogix controllers, firmware version 20.011 or later
• 1769-L24ER-QB1B, 1769-L24ER-QBFC1B, 1769-L27ERM-QBFC1B
CompactLogix controllers, firmware version 20.011 or later
• 1769-L16ER, 1769-L18ER, 1769-L18ERM CompactLogix controllers, firmware version 20.011 or later
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Chapter 1 Socket Interface Architecture
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 .
Before you use the socket interface, ensure 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
Logix5000 controller communicates
• How to write ladder logic or structured text for a Logix5000 controller
Socket Interface Architecture
The socket interface is implemented via the socket object in the EtherNet/IP module. Logix5000 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 other device’s application protocol. The EtherNet/IP module has no application protocol knowledge. The module makes only the socket services available to programs in
Logix5000 controllers.
Number and Type of Sockets
The 1756-EN2
xx modules and CompactLogix 5370 controllers support
32 socket instances. The 1756-EWEB and 1768-EWEB modules support 20 socket instances. Each instance can be one of these types:
• UDP socket—Sends and receives UDP datagrams.
• TCP client socket—The Logix5000 program initiates the connection.
• TCP server socket—Another device initiates the connection to the
Logix5000 program.
• TCP listen socket—Listens on a specified port number for incoming connections.
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Socket Interface Architecture Chapter 1
These options are available for UDP and TCP send and receive services.
Type
UDP
TCP
Communication
Unicast
Multicast
Broadcast
Unicast
Multicast
Broadcast
Yes
NA
NA
Send (Write)
Yes
Yes
Yes
Yes
NA
NA
Receive (Read)
Yes
Yes
Yes
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 Create
OpenConnection
AcceptConnection
ReadSocket
WriteSocket
DeleteSocket
DeleteAllSockets
ClearLog
JoinMulticastAddress
DropMulticastAddress
Socket Instance
Server or client
Client
• 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.
Server or client
Server or client
Server or client
Server or client
Server or client
Server or client
Server or client
Page
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.
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Chapter 1 Socket Interface Architecture
Controller
Typical Sequence of Transactions for a TCP Client
The following diagram shows a typical sequence of socket interface transactions with the Logix5000 controller acting as a TCP client. Each transaction between the Logix5000 controller and the EtherNet/IP module is a MSG instruction.
The following example shows the Logix5000 controller sending data to a device and then the device sending a response. This is a typical sequence of transactions.
Depending on the application protocol, the device could instead initiate sending data to the Logix5000 controller once the connection is open.
Also, each write transaction does not require an application response or acknowledgement. The application protocol determines the exact sequence of application transactions.
EtherNet/IP Module
10.10.10.10
Device
10.10.10.11
Create Socket
Create Socket Response
Instance = 102
OpenConnection
"10.10.10.11?Port=49200"
Open TCP
Connection
Accept Connection
OpenConnection Response
Write Data = abc
Write Response
Read
Read Response Data = xyz
Data = abc
The response is returned to the controller as soon as the data is sent.
Data = xyz
Receive Data
Send Data
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Typical Sequence of Transactions for a TCP Server
The following diagram shows a typical sequence of socket interface transactions with the Logix5000 controller as a TCP server. Each transaction between the
Logix5000 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.
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EtherNet/IP Module
10.10.10.10
Socket Interface Architecture Chapter 1
Device
10.10.10.11
Controller
Create Socket
Port = 49100
Create Socket Response
Instance = 102
AcceptConnection
AcceptConnection Response
Read
Read Response
Data = abc
Write
Data = xyz
Write Response
The response is returned to the controller as soon as the data is sent.
Open TCP Connection
Port=49100
Data = abc
Data = xyz
Open Connection
Send Data
Receive Data
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 Logix5000 controller specifies the destination for each datagram and receives the sender’s address along with each datagram it receives. Each transaction between the Logix5000 controller and the
EtherNet/IP module is a MSG instruction.
The example below shows the Logix5000 controller sending data to a device and then the device sending a response. This is a typical sequence of transactions.
Depending on the application protocol, the device could instead initiate sending data to the Logix5000 controller. Also, each Write transaction does not require an application response or acknowledgement. The application protocol determines the exact sequence of application transactions.
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Chapter 1 Socket Interface Architecture
Controller
Create Socket
Port=49100
Create Socket Response
Instance = 102
Write
10.10.10.11?Port=49200
Data = abc
Write Response
Read
Read Response
10.10.10.11?Port=49200
Data = xyz
EtherNet/IP Module
10.10.10.10
Device
10.10.10.11
Data = abc
The response is returned to the controller as soon as the data is sent.
Data = xyz
Receive Data from Port 49200
Send Data to
10.10.10.10, Port 49100.
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 Logix5000 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.
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EtherNet/IP Module
10.10.10.10
Socket Interface Architecture Chapter 1
Device
10.10.10.11
Controller
Create Socket
Port=49100
Create Socket Response
Instance = 102
Open Connection
10.10.10.11?Port=4920
Open Connection Response
Write
Data = abc
Write Response
Read
Read Response
10.10.10.11?Port=49200
Data = xyz
Data = abc
The response is returned to the controller as soon as the data is sent.
Data = xyz
Receive Data from Port 49200
Send Data To
10.10.10.10, Port 49100
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Chapter 1 Socket Interface Architecture
Communicate with the
Socket Object via a MSG
Instruction
In a Logix5000 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 Table 1 .
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Table 1 - Configuration Tab
Field
Message Type
Service Type
Service Code
Class
Instance
Attribute
Description
Choose CIP Generic.
Depending on your version of RSLogix™ 5000 software, do one of the following:
• With RSLogix 5000 software, version 15 or later, choose a socket service type. The software automatically completes the Service Code and Class fields.
• With RSLogix 5000 software, version 15 or earlier, choose Custom. Manually complete the
Service Code and Class 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 43 .
Type the unique service code that corresponds to the socket service you chose in the Service
Type field.
Type 342 (hexadecimal) for the socket object.
Type one of these values:
• 0 for Socket Create, Delete All Sockets, and ClearLog services
• Instance number 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.
Type an attribute value only when getting or setting an attribute, but not when using other services.
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Socket Interface Architecture Chapter 1
Table 1 - Configuration Tab
Field
Source Element
Description
Choose the tag that contains the request parameters for the socket service. To define the request parameters, create a user-defined data type for the tag.
Enter the length of the source element.
Source Length
Destination Element Choose the tag that contains the response data returned by the socket service. To define the response data, create a user-defined data type for the tag.
On the Communication tab, configure the parameters described in Table 2 .
IMPORTANT
All CompactLogix 5370 controllers must use unconnected MSG instructions. If you are configuring a message for a CompactLogix 5370 controller, make sure the Connected checkbox on the Message Configuration dialog box is cleared.
Table 2 - Communication Tab
Field
Path
Large Connection
(1)
Description
Enter the communication path to the EtherNet/IP module. The module must be accessed via the backplane; you cannot access the module via the Ethernet port.
For all CompactLogix 5730 controllers path is 1,0 .
Select the checkbox to use a large 4000 byte connection size, or clear the checkbox to use a standard 500 byte connection size.
A large connection is only available with connected MSG instructions. For information about using the Connected or Cach Connections options, refer to the Logix5000 Controllers Messages
Programming Manual, publication 1756-PM012 .
IMPORTANT: To efficiently use controller memory, use large connections only for ReadSocket or WriteSocket services that require more than the standard 500-byte connection size, as shown in Table 3 .
(1)Large connections are supported only by 1756-EN2xx ControlLogix modules in RSLogix 5000 software, version 20 or later.
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Chapter 1 Socket Interface Architecture
Service Timeouts
The maximum amount of data you can send or receive depends on how you configure the MSG instruction, as shown in Table 3 . The size of the data does not include the parameters in the ReadSocket and WriteSocket services.
Table 3 - Maximum Packet Sizes
Service
ReadSocket
WriteSocket
Unconnected Size
484 bytes
462 bytes
Standard Connection Size Large Connection Size
484 bytes 3984 bytes
472 bytes 3972 bytes
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.
You must specify a time-out 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 time-out period expires, the socket object returns a response to the service request. See the service descriptions
for the content of the response.
IMPORTANT
Make the value of the service time-out parameter shorter than the MSG instruction timeout. Otherwise, application data could be lost.
MSG Instruction Timeouts
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.
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.
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 specified by the inactivity timeout, the socket instance is deleted. If you then try to use the
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Socket Interface Architecture Chapter 1 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 45 .
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 the inactivity timeout is longer than the longest interval between socket operations. If the inactivity timeout is too short, socket instances can time out, resulting in MSG instruction errors.
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 handle 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 49 .
Depending on the application, try these actions:
• Try to reestablish 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 reestablish 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 new 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.
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Chapter 1 Socket Interface Architecture
ControlLogix Enhanced Redundancy
IMPORTANT
Socket instances 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.
• Sockets 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. This
loss of communication, as described in TCP Connection Loss on page 19
, is caused by a change in the EtherNet/IP module's IP address after a switchover.
• 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 prior to a second switchover, your application program can issue a message to delete all the 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 new 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 may 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
Logix5000 program reinitializes its socket communication.
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Socket Interface Architecture Chapter 1
Change Controller Mode between Run and Program
If the Logix5000 controller transitions from Run mode to Program mode while socket requests are active, the transition does not complete until all of the 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 Logix5000 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 Run-Program-Run transitions because all of the 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 Logix5000 program starts, use the DeleteAllSockets service to delete any previous instances.
The DeleteAllSockets service deletes all socket instances, not just those created by the controller calling 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 containing 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.
Application Messages and Uninhibited 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.
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Chapter 1 Socket Interface Architecture
22
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.
/* 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;
Partial Writes
Although uncommon, your program can need to handle a situation where a write service is unable to send all of the specified bytes. Such a situation can occur if the write service is called multiple times before the target application can receive the data.
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Socket Interface Architecture Chapter 1
If the write service is not able to send all of 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, as well as the actual length of the data sent.
This fragment of structured text logic shows an example of handling a partial write service.
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; end_if;
Performance Considerations
As noted previously, the socket interface enables a Logix5000 controller to communicate via an EtherNet/IP module with Ethernet devices, such as bar code scanners, RFID readers, or other standard Ethernet devices, that do not support the EtherNet/IP application protocol. 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 a variety of factors that can affect the performance of the socket interface. For examples of some of the factors to consider, search the
Knowledgebase for Answer ID 36682. To access the Knowledgebase, log on to the Support Center at http://rockwellautomation.custhelp.com/ .
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Chapter 1 Socket Interface Architecture
Notes:
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Chapter
2
Socket Object Services
Topic
Page
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, Logix5000 controllers store data in CIP byte order (little endian). For example, if you issue a write service with 1 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 Logix5000 controller assumes the incoming data is in CIP byte order. Depending on the native byte order of the application you are communicating with, you can need to convert the byte order in your Logix5000 program or in the application.
To check your MSG configuration in RSLogix 5000 software, version 15 or later, 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
Socket Create
Parameter
Service Type
Service Code
Class
Instance
Attribute
0
0
Value
Socket Create
4b
342
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 Table 4 to define the data type.
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Table 4 - Data Type for Socket Create Source Element
Member Name Data Type
Type DINT
Addr
Family
Port
Addr structure
INT
INT
DINT
Description
Specify one of these values:
• 1 for TCP
• 2 for UDP
A user-defined structure that specifies the address for the socket.
Specify the address family. Must be 2.
Specify the local port number on which an application is listening and receiving, or set to 0 if you want the EtherNet/IP module to choose the local port number:
• For TCP client operations, specify 0 unless you want a specific local port number.For TCP server communication, specify the port number on which to accept incoming connection requests.
• For UDP, specify a local port number to receive datagrams on a specific port.
Specify an IP address. Typically, set to 0 (any address).
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 just created to the destination element. Specify a DINT tag.
Considerations
Use the instance 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. The EtherNet/IP module uses these port numbers:
• 20, 21—FTP
• 25—SMTP
• 80—HTTP
• 123—NTP
• 161—SNMP
• 2222—EtherNet/IP
• 44818—EtherNet/IP
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Chapter 2 Socket Object Services
OpenConnection
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
OpenConnection
4c
342 from Socket Create
0
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 Table 5 to define the data type.
28
.
Table 5 - Data Type for OpenConnection Source Element
Member Name Data Type
Timeout DINT
DestAddr STRING
.LEN
.DATA
DINT
SINT array
Description
Specify the timeout in milliseconds.
Specify an array of characters (maximum of 64) to define the destination of the connection. Specify either of these:
• Hostname?port=
xxxzaz
• IPAddr?port=
xxx
For example, to specify an IP address, enter 10.88.81.10?port=2813
The length of the destination address.
The array containing the destination address.
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Socket Object Services Chapter 2
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.
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 time-out 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 time-out 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 previouslyspecified IP address and port number until you call the OpenConnection service to specify a different 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, in addition to the data, you receive 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
AcceptConnection
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
AcceptConnection
50
342 from Socket Create
0
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
Choose a DINT tag to contain the timeout in milliseconds.
MSG Source Length
Specify 4 bytes (Timeout).
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MSG Destination Element
Choose a tag with a user-defined data type. Use the information in Table 6 to define the data type.
Table 6 - Data Type for AcceptConnection Destination Element
Member Name Data Type
Instance DINT
Addr
Family
Port
Addr structure
INT
INT
DINT
Description
Contains the instance for this service. Use this Instance on subsequent Read and Write services for this connection.
IMPORTANT: Copy this Instance number to Read and Write Messages
A user-defined structure that contains the address for the socket.
Contains the address family. Must be 2.
Contains a remote port number.
Contains a remote IP address.
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 subsequently reading and writing data.
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Chapter 2 Socket Object Services
ReadSocket
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
ReadSocket
4d
342
See
0
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 time-out 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 can 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 returned from the CreateConnection service.
However, when accepting a connection via the AcceptConnection service, use the instance 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 Table 7 to define the data type.
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Table 7 - Data Type for ReadSocket Source Element
Member Name
Timeout
BufLen
Data Type
DINT
DINT
Description
Specify the timeout in milliseconds.
Specify the number of bytes of data to receive.
MSG Source Length
Specify 8 bytes (Timeout + BufLen).
MSG Destination Element
Choose a tag with a user-defined data type. Use the information in Table 8 to define the data type.
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Chapter 2 Socket Object Services
WriteSocket
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
WriteSocket
4e
342
0
Table 8 - Data Type for ReadSocket Destination Element
Member Name Data Type
FromAddr structure
Family
Port
Addr
BufLen
Buf
INT
INT
DINT
DINT
SINT array
Description
A user-defined structure that contains the address of the device sending UDP data.
For TCP, this structure is not used and contains all zeros. The TCP connection conveys all remote address information.
Contains the address family for UDP. Must be 2.
Contains the remote port number for UDP. This is the port that the remote device uses for receiving.
Contains the remote IP address for UDP
Contains the number of bytes of data received.
Contains the data.
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].
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
This service uses the instance returned from the CreateConnection service.
However, when accepting a connection via the AcceptConnection service, use the instance returned from this AcceptConnection service as the WriteSocket instance.
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MSG Source Element
Choose a tag with a user-defined data type. Use the information in Table 9 to
define the data type.
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Chapter 2 Socket Object Services
Table 9 - Data Type for WriteSocket Source Element
Member Name Data Type
Timeout DINT
ToAddr structure
Family
Port
Addr
BufLen
Buf
INT
INT
DINT
DINT
SINT array
Description
Specify the timeout in milliseconds.
A user-defined structure that contains the address to which to write UDP data.
For TCP, this structure is not used and contains all zeros. The TCP connection conveys all required remote address information.
Specify the address family. Must be 2 for UDP.
Specify the remote port number for UDP. This is the port that the remote device uses for receiving.
Specify the remote IP address for UDP.
Specify the number of bytes of data to write.
Contains the data.
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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DeleteSocket
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
DeleteSocket
4f
342 from Socket Create
0
Socket Object Services Chapter 2
The DeleteSocket service deletes a socket instance. For a TCP connection, the
DeleteSocket service also closes the connection prior to deleting 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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Chapter 2 Socket Object Services
DeleteAllSockets
The DeleteAllSockets service deletes all currently created socket instances. For
TCP, the DeleteAllSockets service also closes all connections prior to deleting the instances.
Choose Custom for the service type. DeleteAllSockets is not an available option from the Service Type pull-down menu.
Parameter
Service Type
Service Code
Class
Instance
Attribute
0
0
Value
Custom
51
342
38
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 created by all controllers, not just the controller calling the service.
Use the DeleteAllSockets service as the first operation when the program first begins to operate.
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ClearLog
Parameter
Service Type
Service Code
Class
Instance
Attribute
0
0
Value
Custom
52
342
Socket Object Services Chapter 2
The ClearLog service clears the debug log on the TCP/IP Socket Object web page. This service does not change the logging options.
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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Chapter 2 Socket Object Services
JoinMulticastAddress
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
Custom
53
342 from Socket Create
0
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 at the same time. 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 Table 10 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 hexidecimal representation of the IP address. For example, for address 239.1.2.100, enter 16#EF010264.
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DropMulticastAddress
Socket Object Services Chapter 2
Table 10 - Data Type for JoinMulticastAddress Source Element
Member Name Data Type
SocketsAddr structure
Family
Port
Addr
INT
INT
DINT
Description
A user-defined structure that specifies the multicast address to join.
Specify the address family. Must be 2.
Not used. The port is determined when the socket is created.
Specify the multicast IP address to receive from.
MSG Source Length
Specify 8 bytes.
MSG Destination Element
Not used.
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.
Parameter
Service Type
Service Code
Class
Instance
Attribute
Value
Custom
54
342 from Socket Create
0
25302
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Chapter 2 Socket Object Services
MSG Source Element
Choose a tag with a user-defined data type. Use the information in Table 11 to define the data type.
Table 11 - Data Type for DropMulticast Address Source Element
Member Name Data Type
SocketsAddr structure
Family
Port
Addr
INT
INT
DINT
Description
A user-defined structure that specifies the multicast address to drop.
Specify the address family. Must be 2.
Not used. The port is determined when the socket is created.
Specify the multicast IP address to drop.
MSG Source Length
Specify 8 bytes.
MSG Destination Element
Not used.
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Chapter
3
Socket Attributes
Topic
Page
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
Socket Class 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
below.
• For information about a specific socket instance, type the specific socket instance number in the Instance field. The instance number is returned by a Socket Create or AcceptConnection service. See
Instance Attributes on page 45 .
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.
Access Description
3
8
1
2
Class
Attribute
Name
Revision
Max Instance
Number of Instances INT
Log Enable DINT
Data
Type
INT
INT
Get
Get
Get
Get
Set
Object revision.
Largest socket instance number currently created.
Number of socket instances currently created.
Enable (1) or disable (0) logging to the Socket Object
Log web page.
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
If you use the Get Attributes All service to get class attributes, the response contains all of the class attributes in the table above 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 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.
Name Data Type Access Description Instance
Attribute
1 (16#01)
2 (16#02)
3 (16#03)
4 (16#04)
5 (16#05)
6 (16#06)
7 (16#07)
8 (16#08)
LocalAddr
RemoteAddr
SendBufSize
RecvBufSize
TCPKeepAlive
TCPNoDelay
InactivityTimeout
MulticastTTL
Struct SockAddr
Struct SockAddr
DINT
DINT
DINT
DINT
DINT
DINT
Get
Set
Get
Set
Get
Set
Get
Get
Get
Set
Get
Set
Local address for the socket.
Remote address for the socket.
Size of the socket send buffer (bytes).
Size of the socket receive buffer (bytes).
Enable (1) or disable (0) TCP Keep Alive for the socket.
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 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.
9 (16#09) UDPBroadcast
10 (16#0A) LingerOnOff
DINT
DINT
Get
Set
Get
Set
Get
Set
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. Setting linger to non-zero results in the standard TCP connection close sequence (3-way 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 of the attributes in the table above in the order 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.
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Chapter 3 Socket Attributes
Notes:
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Chapter
4
Troubleshoot Socket Applications
Diagnostic Web Pages
Topic
Error Codes for Socket Services
Page
To help debug and troubleshoot applications, the socket interface provides a set of web pages:
• For communication modules and controllers, go to Diagnostics >
Advanced Diagnostics > Miscellaneous > System Data > Socket Object.
• For web server modules, go to Diagnostics > Advanced Diagnostics.
Web Page
Socket Object Diagnostics
Socket Object Attributes
Socket Object Logs
Description
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
Displays attribute settings for each instance
Displays a log of service requests with a maximum of 100 log entries:
• Service requests made to the socket object
• Parameters 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 44 .
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Chapter 4 Troubleshoot Socket Applications
Debugging Tips
This table describes tips for debugging problems by category.
Category
EtherNet/IP module
Socket Create service
MSG instruction
OpenConnection service
Service Timeout parameter
TCP protocol
Ethernet sniffer
Consideration
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.
Make sure the Destination tag is a DINT tag.
After creating the socket with the Socket Create service, make sure you use the instance number that the service returns in the subsequent socket services you call.
Make sure the Source Element is of a type that matches the request parameters for the requested service. Also make sure the Source Length is the correct length for the service parameters.
There is a limit to the number of active MSG instructions in a Logix5000 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).
Make sure the Source Length includes the size of the Timeout parameter + Address
Length parameter + the Length of the address itself.
Make sure the Timeout parameter is sufficient for the service. Also make sure the
Timeout parameter is less than the MSG instruction timeout.
If the timeout set to 0, the service returns immediately.
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.
An Ethernet sniffer is useful to monitor the messages between the EtherNet/IP module and other devices. You can capture network traffic and set up filters to isolate messages between particular devices and particular messages between those devices.
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Error Codes for
Socket Services
Troubleshoot Socket Applications Chapter 4
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, search the Knowledgebase for Answer ID 34290.
Error Code
16#0002
16#0004
16#0005
Extended Error Code
16#0000_0000 or
16#0000_0001
16#0008
16#0009
16#000b or
16#000c
16#000d
16#0013 or
16#0015
16#0020
16#00ff
16#00ff
16#00ff
16#00ff
16#00ff
16#0000_0016 or
16#0000_0033
16#0000_0030
16#0000_0036
16#0000_0039
16#0000_003d
Description
Simultaneous execution of Read, Write, or Delete messages.
Attempt to access Socket Object via Ethernet port is blocked because of resiliency concerns.
For more information, search the Knowledgebase for Answer ID 606391 - Logix Sockets message error 16#0004 .
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 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 socket was deleted by the DeleteSocket service.
ENxT or ENxTR module that is used for socket messages is in a remote chassis that is connected to the controller over the
ControlNet network or is using an older EtherNet/IP module that supports only 478-byte messages.
For more information, search the Knowledgebase for Answer ID
573325 - Open Sockets: Message Read/Write error 16#0008 if "Large Connection" option is enabled .
Invalid socket descriptor. To resolve this error, do the following:
• Make sure a valid socket instance exists.
• Make sure the message source data format and source values are correct.
• For Create messages, make sure 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, search the Knowledgebase for Answer ID 515562 - Open Sockets Error codes 16#000b, 16#000c .
Invalid data in Source UDT.
The ‘Write’ message instruction Source length must be exactly equal to the buffer length+16.
For more information, search the Knowledgebase for Answer ID 515604 - Open Sockets Error code 16#0013 and 16#0015 .
The ‘Write’ message instruction Source length is less than 17 bytes. Length must be exactly equal to the buffer length+16.
For Connect messages, make sure Destination String address includes
‘?port=xxxx’ similar to 192.168.1.34?port=9100.
For more information, search the Knowledgebase for Answer ID 490971 - 1756-EN2T, 1756-EWEB 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, search the Knowledgebase for Answer ID
522458 - Open Sockets: Open connection fails with error 16#0000_0046,16#0000_0016 or 16#0000_0033 .
The address is already in use. This error can occur when multiple Socket Create requests are issued to the same port address.
A connection was forced closed by a peer. This error can occur when a remote device closes a connection with a Logix module without notifying the module.
To resolve this error, try deleting the socket and then reconnecting to the remote device.
In Server mode, instance number from Accept Message was not copied to Read/Write messages.
A connection refused by a peer. Possibly peer is out of connections if Logix module closes them without Linger Attribute set.
For more information, search the Knowledgebase for Answer ID 493294 - Logix Open Sockets Linger Control .
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Chapter 4 Troubleshoot Socket Applications
Error Code
16#00ff
Extended Error Code
16#0000_0041
16#00ff
16#00ff
16#00ff
16#0000_0043
16#0000_0046
16#0009_0315
Description
A socket operation could not find a route to the remote host. This error typically occurs in these scenarios:
• A remote IP address 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’s properties.
• UDP multicasts messages to an unpingable IP address require you to specify a gateway address in the Logix module’s properties even if a gateway address does not exist or is not required.
For more information, search the Knowledgebase for Answer ID 34358 - 1756-EWEB socket errors 16#0041 and 16#0043 .
The remote device or gateway is not responding.
This error can occur if a UDP multicast message is sent to a gateway address that is not specified in the Logix module’s properties.
For more information, search the Knowledgebase for Answer ID 34358 - 1756-EWEB socket errors 16#0041 and 16#0043 .
The socket operation timed out. Known reasons include the following:
1. Connect Service message:
– Server IP exists, but port does not.
– Server IP and port exist, but it does not accept connection on this port .
– Service ‘timeout’ value in UDT set to 0 or very low value.
The peer device reports WIN=0 and the 1756-EN2T module immediately closes the connection. For more information, search the Knowledgebase for Answer ID
522458 - 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 at the same time.
For more information, search the Knowledgebase for Answer ID 515420 - Open Sockets message Error 16#00FF extended
16#0000_0046 .
Invalid Path string manually (or programmatically) entered to the MSG.Path string.
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Rockwell Automation Publication ENET-AT002C-EN-P - September 2014
Knowledgebase Articles
Troubleshoot Socket Applications Chapter 4
Search the Knowledgebase by using the Answer IDs in the table below to find additional help. To access the Knowledgebase, log on to the Rockwell
Automation Support Center at http://rockwellautomation.custhelp.com/ .
Answer ID
32962
34290
40626
48879
493378
50122
587225
Description
Sample applications for the 1756-EWEB module.
Descriptions of possible socket error codes.
Helpful hints for socket services.
Summary of major sockets topics and functionality descriptions.
AOI example for using sockets to read time from NTP or SNTP server
Using sockets in AOIs (Add-on Instructions).
Using Sockets for Email with Basic Login Authentication
Rockwell Automation Publication ENET-AT002C-EN-P - September 2014
51
Chapter 4 Troubleshoot Socket Applications
Notes:
52
Rockwell Automation Publication ENET-AT002C-EN-P - September 2014
Index
A
AcceptConnection service 30–31
access
application messages
TCP considerations 21 uninhibited module considerations 21
architecture, socket interface
number and type of sockets 10, 11 overview 10
attributes
B
C
change
communication
connection loss 19 considerations, programming 19–23
ControlLogix enhanced redundancy 20 crossload 20
D
DropMulticastAddress service 40–41
E
Rockwell Automation Publication ENET-AT002C-EN-P - September 2014
EtherNet/IP module
I
instruction, MSG
J
JoinMulticastAddress service 39–40
K
L
Logix5000 controller
as TCP client 12 as TCP server 12
M
messages
TCP considerations 21 uninhibited module considerations 21
MSG instruction
O
OpenConnection service
P
partial reads 22 partial writes 22
53
Index
54
programming considerations 19–23
R
reset
S
sequence of transactions
services
Socket Create service
socket instances
socket interface
number and type of sockets 10, 11
programming considerations 19–23
socket object attributes 47 socket object diagnostics 47 socket object logs 47
Rockwell Automation Publication ENET-AT002C-EN-P - September 2014
socket object services
instances 11
overview 11, 25
T
transaction sequence
troubleshooting
U
uninhibited modules
application message considerations 21
W
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Publication ENET-AT002C-EN-P - September 2014
Supersedes Publication ENET-AT002B-EN-P - July 2014 Copyright © 2014 Rockwell Automation, Inc. All rights reserved. Printed in the U.S.A.
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