copyright © 2012 kendall electric, inc. all rights reserved. socket services lunch & learn...

Copyright © 2012 Kendall Electric, Inc. All rights reserved.

Socket Services Lunch & Learn

Presented by:Eric PaquetteAutomation SpecialistKendall Electric

Agenda

• What Is It?• Understanding Basic Socket Services• How is it Different from Standard Ethernet Communications• Explanation of New Hardware Capable of Socket Comms• Socket Services Hints• Setting it Up• Review of Error Codes – Common and Others• Some Examples• Reference Tools • Setting Up and Using Logging with the EWEB


What is a socket?

• A socket is one of the most fundamental technologies of computer networking.

• Sockets allow applications to communicate using standard mechanisms built into network hardware and operating systems.

• Although socket technology may seem to be a relatively new topic, socket technology actually has been around for roughly two decades.

• Sockets are bidirectional, meaning that either side of the connection is capable of both sending (writing) and receiving (reading) data.

• The application that initiates communication is termed the “client” and the other application the “server”.

• Sockets are created using an IP address and a port number.


Who uses socket interfaces?

• Almost all networked hardware and software.

• Historically sockets have been of interest mainly to computer programmers.

• Most, if not all, programming languages use libraries that implement application programming interfaces (API’s) to access socket communications. Microsoft uses Windows Sockets (Winsock).

• Since the widespread growth of Ethernet in factory floor automation, a need was created to make a more generic socket interface. Not all products speak EtherNet/IP.


Types of sockets

• Sockets are divided into three categories: Stream, Datagram and Raw

• Stream– TCP/IP– Connection Oriented– Most Common– Requires two devices to establish a connection in advance

• Datagram– UDP– Connectionless– Implicit– More efficient data transfer

• Raw– Custom low-level programming– Not common


EtherNet/IP vs. Open-Socket Interface

• EtherNet/IP is a protocol and does in fact use sockets to communicate between devices.

• EtherNet/IP products from Rockwell set up the socket connections automatically. No user programming is needed


EtherNet/IP Open-Socket Interface

Uses Sockets to communicate between devices

Uses standard Ethernet technology

Application Layer Protocol

Requires Complex Programming to configure

TCP/IP packet capability

UDP packet capability

Used by Rockwell I/O

Used by Third Party Devices

What can I use Sockets for?


• Control data can be easily consumed by an external application using the XML data markup (Data Views)

• Standard XML data presentation provides a platform neutral environment (works on all Operating Systems)

w/ EWEB support

RFID Readers

Printers

Sockets Connection (using the MSG Instruction)

XML Data (via Data Views)

Any Standard Ethernet Devices (ie: Robots)

Non-Windows Based Workstations

• The EWEB modules support both TCP and UDP socket types. Up to 20 Socket connections per module.

• The MSG instruction in RSLogix 5000 is used to setup and pass data thru Socket connections to other devices

http://www.kuka.com/en/products/robots/

Which Rockwell Products Support an Open-Socket Services?

• 1756-EWEB

• 1768-EWEB

• 1756-EN2xx

• 1769-L30ER, 1769-L30ERM, 1769-L30ER-NSE, 1769-L33ER, 1769-L33ERM, and 1769-L36ERM CompactLogix controllers

• 1769-L24ER-QB1B, 1769-L24ER-QBFC1B, 1769-L27ERM-QBFC1B CompactLogix controllers

• 1769-L16ER, 1769-L18ER, 1769-L18ERM CompactLogix controllers


How is it implemented?

• Rockwell Products that support open-socket services contain a socket object that is available for creating connection instances.

• Socket Instances are created in the EWEB using Message (MSG) Instructions in the PAC.

• The MSG instructions use a CIP Generic messages manage the Socket Instances. This is similar to the socket API function calls in most programming languages.

• Each MSG Instruction is configured to perform one of the many different Socket Services. (Create, Open, Read, Write, Delete, etc.)

• To communicate with another device you must understand the other devices application protocol. For example: the Socket Write must send the data in the proper format for the end device to understand it.


Socket Object Services

• Create Socket• Delete Socket• Delete All Sockets• Open Connection (Client)• Accept Connection (Listen)• Read Data• Write Data• Clear Log• Join Multicast Address• Drop Multicast Address


Typical TCP Client


Typical TCP Server


Using MSG Instructions


Socket Attributes

• Socket Attributes can also be obtained using message instructions.

• These are divided into two catergories:– Class Attributes (apply to the Socket Object)– Instance Attributes (apply to each Socket Instance)


Timeouts! Timeouts! Timeouts!

• There are three types of timeouts to be concerned with:– Service Timeouts

• Should be less than the MSG timeout• Set in the Source Tag of the MSG

– MSG Instruction Timeouts• 30 Sec is Default, can be up to 35 minutes• Set in the MSG Configuration Tab

– Socket Instance Timeouts• 5 minutes is default• Set by accessing the Socket Instance Attributes


Socket Object Logging

• The EWEB cards are capable of logging activity and errors and are stored in RAM of the module

• Logging is viewed on the Web Pages of EWEB module

• Items logged can be selectively chosen

• The log can be enabled, disabled, or cleared from within the controller using a Socket Class Attribute MSG


Socket Object Logging (cont’d)

• Logging can be enabled for the following:– Socket Create Requests– Open Connection Requests– Accept Connection Requests– Read Requests– Write Requests– Delete Socket and Delete All Socket Requests– Get / Set Attribute Requests– Log All Service Errors


Socket Object Logging (cont’d)

• A view of the EWEB Log Web Page


Errors

• Message Instruction Errors contain two parts:– Error Code– Extended Error Code

• Error Codes 0 to FE are MSG Errors– See page 165 of 1756-RM003N-EN-P

• Socket Service Errors Codes are generally FF

• When evaluating errors from Socket Service Messages, we typically look at the Extended Error Code– See page 155 of ENET-UM527-EN-P


Knowledgebase Articles

• 48879 – Summary of EWEB socket Information

• 32962 – Sample Application in Ladder

• 40626 – Socket Service Hints

• 470690 – List of Hardware with Socket Support

• 66505 – Basic Socket Code in Structured Text

• 33240 – Using EWEB with Ethernet Printers

• 33672 – EWEB TCP Server application sample

• 34357 – Send UDP multicast messages


Let’s see it in action!

Demo



Thank you for attending this Lunch & Learn session!

Questions?

copyright © 2012 kendall electric, inc. all rights reserved. socket services lunch & learn...

Documents

socket interfaces

socket instances

socket technology

socket object

socket communications

socket connections

kendall electric

opensocket services