Mathworks OPC TOOLBOX 2 user guide

OPC Toolbox™ 2

User’s Guide

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OPC Toolbox™ User’s Guide

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Revision History

June 2004 Online only New for V ersion 1.0 (Release 14) August 2004 Online only Revised for Version 1.1 (Release 14+) October 2004 Online only Revised for Version 1.1.1 (Release 14SP1) March 2005 Online only Revised for Version 1.1.2 (Release 14SP2) April 2005 Online only Revised for Version 2.0 (Release 14SP2+) September 2005 Online only Revised for Version 2.0.1 (Release 14SP3) March 2006 Online only Revised for Version 2.0.2 (Release 2006a) September 2006 Online only Revised for Version 2.0.3 (Release 2006b) March 2007 Online only Revised for Version 2.0.4 (Release 2007a) September 2007 Online only Revised for Version 2.1 (Release 2007b) March 2008 Online only Revised for Version 2.1.1 (Release 2008a) October 2008 Online only Revised for Version 2.1.2 (Release 2008b) March 2009 Online only Revised for Version 2.1.3 (Release 2009a) September 2009 Online only Revised for Version 2.1.4 (Release 2009b) March 2010 Online only Revised for Version 2.1.5 (Release 2010a)

Introduction

Product Overview ................................. 1-2

About OPC Toolbox Software About OPC Understanding OPC Data Access Servers Understanding the OPC Toolbox Object Hierarchy How OPC Toolbox Objects Relate to OPC Servers System Require ments

....................................... 1-3

.............................. 1-8

........................ 1-2

.............. 1-4

...... 1-6

....... 1-7

Contents

Getting Comm and-Line Function Help

Preparing to Use OPC Toolbox Software

Introduction Installing the OPC Foundation Core Components Configuring DCOM Installing the Matrikon OPC Simulation Server

Exploring A vailable OPC Servers

Prerequisites Determining Server IDs for a Host

Connecting to OPC Servers

Overview Creating a Client Object Connecting a Client to the Server Browsing the OPC Server Name Space

Troubleshooting

Introduction Unable to Find an OPC Server “Class not registered” Error Unable to Query the Server Unable to Connect to Server Unable to Create a Group Error While Querying Interface

...................................... 1-10

................................ 1-11

................... 1-19

..................................... 1-19

................... 1-19

......................... 1-21

........................................ 1-21

............................ 1-21

.................... 1-22

................ 1-23

................................... 1-28

...................................... 1-28

....................... 1-28

......................... 1-29

........................... 1-29

...................... 1-29

.............. 1-9

............. 1-10

....... 1-10

........ 1-18

Quick Start: Using the OPC Tool G UI

Example: Basic OPC Toolbox Acquisition Procedure .. 2-2

Overview Step 1: Open the OPC Tool GUI Step 2: Locate Your OPC Server Step 3: Create an OPC Data Access Client Object Step 4: Connect to the OPC Server Step 5: Create an OPC Data Access Group Object Step 6: Browse the Server Name Space Step 7: Add OPC Data Access Items to the Group Step 8: View All Item Values Step 9: Configure Group Properties for Logging Step 10: Log OPC Server Data Step 11: Plot the Data Step 12: Clean Up

........................................ 2-2

..................... 2-3

..................... 2-4

....... 2-6

................... 2-10

....... 2-12

................ 2-13

....... 2-17

........................ 2-21

......... 2-23

....................... 2-25

.............................. 2-26

................................. 2-28

Using OPC Toolbox Objects

vi Contents

Creating OPC Toolbox Objects ...................... 3-2

Overview Creating Data Access Group Objects Creating Data Access Item Objects Building an Object Hierarchy with a Disconnected

Client Creating OPC Toolbox Object Vectors Working with Public Groups

Configuring OPC Toolbox Object Properties

Purpose of Object Properties Viewing the Values of Object Properties Viewing t h e Value of a Particular Property Getting Information About Obje ct Properties Setting the Value of an Object Property Viewing a List of All Settable Object Properties

Deleting Objects

........................................ 3-2

.................. 3-2

................... 3-5

......................................... 3-8

................. 3-9

........................ 3-12

......... 3-17

........................ 3-17

............... 3-18

............ 3-19

........... 3-19

............... 3-20

......... 3-21

................................... 3-23

Saving and Loading Objects ........................ 3-25

Reading, Writing, and Logging OPC Data

Reading and Writing Data .......................... 4-2

Introduction Reading Data from an Item Writing Data to an Item Reading and Writing Multiple Values

...................................... 4-2

......................... 4-2

............................ 4-6

................. 4-8

Data Change Events and Subscription

Introduction Configuring OPC Toolbox Objects for Data Change

Events

How OPC Toolbox Software Processes Data Change

Events

How to Customize the Data Change Event Response

Logging OPC Server Data

How OPC Toolbox Software Logs Data Configuring a Logging Session Executing a Logging Task Getting Logged Data into the MATLAB Workspace

...................................... 4-12

........................................ 4-12

........................................ 4-15

.......................... 4-17

....................... 4-20

.......................... 4-24

Working with OPC Data

Understanding OPC Data: Value, Quality, and

TimeStamp

Introduction The Relationship Between Value, Quality, and

TimeStamp

HowValue,Quality,andTimeStampAreObtained

..................................... 5-2

...................................... 5-2

.................................... 5-2

............... 4-12

..... 4-15

................ 4-17

...... 4-26

...... 5-3

vii

Working with Structure Formatted Data ............ 5-8

When Structures Are Used Example: Performing a Read Operation on Multiple

Items Interpreting Structure Formatted Data When to Use Structure Formatted Data Converting Structure Formatted Data to Array Format

......................................... 5-8

.......................... 5-8

............... 5-10

............... 5-13

.. 5-13

Understanding Array Formatted Data

Array Content Conversion of Logged Data to Arrays

Working with Different Data Types

Conversion Between MATLAB Data Types and COM

Variant Data Types Conversion of Values Written to an OPC Server Conversion of Values Read from an OPC Server Handling Arrays for Item Values

.................................... 5-15

............................. 5-18

..................... 5-20

............... 5-15

................. 5-16

................. 5-18

........ 5-20

Using E vents and Callbacks

Example: Using the Default Callback Function ....... 6-2

Overview Step 1: Create OPC Toolbox Group Objects Step 2: Configure the Logging Task Properties Step 3: Configure the Callback Properties Step 4: Start the Logging Task Step 5: Clean Up

........................................ 6-2

............ 6-2

......... 6-3

............. 6-3

...................... 6-3

.................................. 6-4

viii Contents

Event Types

Retrieving Event Information

Event Structures Example: Accessing Data in the Event Log

Creating an d Executing Callback Functions

Creating Callback Functions

....................................... 6-5

...................... 6-10

.................................. 6-10

............. 6-13

........................ 6-16

......... 6-16

Specifying Callback Functions ....................... 6-18

Example: Viewing Recently Logged Data

.............. 6-20

Using the OPC Toolbox Block Library

Overview ......................................... 7-2

Example: Reading and Writing Data from the Matrikon

OPC Sim ulation Server

Overview Step 1: Open the OPC Toolbox Block Library Step 2: Create a New Model Step 3: Drag the OPC Toolbox Blocks into the Model Step 4: Drag Other Blocks to Complete the Model Step 5: Configure OPC Servers for the Model Step 6: Specify the Block Parameter Values Step 7: Connect the Blocks Step 8: Run the Simulation

........................................ 7-3

.......................... 7-3

........... 7-4

......................... 7-5

....... 7-7

........... 7-9

............ 7-12

.......................... 7-15

......................... 7-16

.... 7-6

Using the OPC Client Manager

Introduction Adding Clients to the OPC Client Manager Removing Clients from the OPC Client Manager Modifying the Server Timeout Value for a Client Controlling Client/Server Connections

...................................... 7-18

...................... 7-18

............ 7-19

........ 7-19

........ 7-20

................ 7-20

Function Reference

Object Creation and Configuration .................. 8-2

Server Exploration

Data Access

....................................... 8-3

................................ 8-2

OPC Data Visualization ............................ 8-3

Logging and Buffering

Simulink Support

Utilities

........................................... 8-5

............................. 8-4

.................................. 8-4

Functions — Alphabetical List

Property Reference

OPC Data Access Client Object Properties ........... 10-2

General Properties Callback Function and Event Properties Server Conne ction Properties

................................ 10-2

............... 10-2

........................ 10-3

x Contents

Data Access Group Object Properties

General Properties Callback Function and Event Properties Subscription and Logging Properties

Data Access Item Object Properties

General Properties Data Propertie s

................................ 10-4

................................ 10-7

................................... 10-7

................ 10-4

............... 10-4

.................. 10-5

................. 10-7

Properties — Alphabetical List

Block Reference

OPC Quality Strings

Major Quality ..................................... A-2

Quality Substatus

Limit Status

.................................. A-3

....................................... A-6

OPC Server Item Properties

Understanding OPC Server Item Properties ......... B-2

OPC Specific Properties

OPC Recommended Properties

............................ B-3

..................... B-4

Index

xii Contents

Introduction

• “Product Overview” on page 1-2

• “Getting Command-Line Function Help” on page 1-9

• “Preparing to U se OPC Toolbox Software” on page 1-10

• “Exploring Available OPC Servers” on page 1-19

• “Connecting to OPC Servers” on page 1-21

• “Troubleshooting” on page 1-28

1 Introduction

Product Overview

About O PC Toolbox Software

OPC Toolbox software is a collection of functions that extend the capability of the MATLAB environment. Using OPC Toolbox functions and blocks, you can acquire live OPC data directly into MATLAB and Simulink, and write data directly to the OPCserverfromMATLABandSimulink.

In this section...

“About OPC Toolbox Software” on page 1-2

“About OPC” on page 1-3

“Understanding O PC Data Access Servers” on page 1-4

“Understanding the OPC Toolbox Object Hierarchy” on page 1-6

“How OPC Toolbox Objects Relate to O PC Servers” on page 1-7

“System Requirements” on page 1-8

environment, and blocks that extend the Simulink®simulation

1-2

OPC Toolbox software implements a hierarchical object-oriented approach to communicating with OPC servers using the OPC Data Access Standard. Using toolbox functions, y ou create an OPC Data Access Client object ( client object) that represents the connection between MATLAB and an OPC server. Using properties of the aspects of the communication link, such as time out periods, connection status, and storage of events associated with that client. “Connecting to OPC Servers” on page 1-21 describes how to create

Once you establish a connection to an OPC server, you create Data Access Group objects ( Items. You then add Data Access Item obje cts ( for monitoring server item values from the OPC server and writing values to the OPC server. You can use the determining how often the items in the group must be updated, executing a MATLAB function when the server provides notif ication of changes in item state, and other tasks related to the group. “Creating OPC Toolbox Objects”

dagroup objects) that represent collections of OPC Data Access

opcda client object you can control various

opcda objects.

daitem objects) to that group,

dagroup object to perform such actions as

opcda

Product Overview

on page 3-2 describes how to create and configure dagroup objects and add

daitem objects to a group.

The OPC Data Access Standard does not provide access to historical data. (While the OPC Foundation has defined the Historical Data Access specification for access to historical data, a significant number of Data Access servers do not support this standard.) Using OPC Toolbox software, you can log records (a list of items that have changed, and their new v alues) from an OPC Data Access Server to disk or to memory, for later processing. The logging task is controlled by the Data” on page 4-17 describes how to log data using the OPC Toolbox logging mechanism.

To work with the data you acquire, you must bring it into the MATLAB workspace. When the records are acquired, the toolbox stores them in a memory buffer or on disk. The toolbox provides several ways to bring one or more records of data into the workspace where you can analyze or visualize the data. Chapter 5, “Working with OPC Data” describes the different data formats and their application.

dagroup object. “Logging OPC Server

You can enhance your OPC application by using event callbacks. The toolbox has defined certain OPC Toolbox software occurrences, such as the start of an acquisition task, as well as OPC server initiated occurrences, such as notification that an item’s stat e has c hanged, as events. You can associate the execution of a particular function with a particular event. Chapter 6, “Using Events and Callbacks” describes this process.

When working in the Simulink environment, you can use blocks from the OPC Toolbox block library to use live OPC data as inputs to your model and update the OPC server with your model outputs. The OPC Toolbox block library includes the capability of running Simulink models in pseudo real time, by slowing the simulation to match the system clock. You can prototype control systems, provide plant simulators, and perform optimization and tuning tasks using Simulink and the OPC Toolbox block library. Chapter 7, “Using the OPC Toolbox Block Library” describes how to use these blocks in a Simulink model.

About OPC

Open Process Control (OPC), also known as O LE for Process Control, is a series of seven specifications defined by the OPC Foundation

1-3

1 Introduction

(http://www.opcfoundation.org) for supporting open connectivity in industrial automation. OPC uses Microsoft communication link between OPC servers and OPC clients. OPC has been designed to provide reliable communicationofinformationinaprocessplant, such as a petrochemical refinery, an automobile assembly line, or a paper mill.

Before you interact with OPC servers using OPC Toolbox software, you should understand the OPC client-server relationship, how OPC servers organize their server i te ms, and how clients can interact with those server items. “Understanding the OPC Toolbox Object Hierarchy” on page 1-6 explains these concepts in detail.

DCOM technology to provide a

Understanding OPC Data Access Servers

OPC Toolbox software is an OPC Data Access client application, capable of connecting to any OPC Data Access compliant server. By utilizing the OPC Foundation Data Access standard, the toolbox does not require any knowledge about the internal configuration and o pe ration of the OPC server. Instead, the Data Access Standard provides the common mechanism for the server and client to interact with each other.

An OP C Data Access Server is identified by a unique server ID. The server ID is unique to the computer on which the server is located. A combination of the host name of the server computer, and the server ID of the OPC server, provides a unique identifier for an OPC server on a network of computers.

1-4

OPC Server Name Spaces

All OPC servers are required to publish a name space, consisting of an arrangement of the name of every server item (also known as a n item ID) associated with that server. The name space provides the internal map of every device and location that the serverisabletomonitorand/orupdate.

The following figure shows a portion of the name space on a typical OPC server.

Product Overview

Figure 1-1: Example of OPC Server and Name Space

A server item represents a value on the OPC server that a client may be interested in. A server item could represent a physical measurement device (such as a temperature sensor), a particular component of a device (such as the set-point for a controller), or a variable or storage location in a s upervisory control and data acquisition (SCADA) system. Each server item is uniquely represented on the server by a fully qualified item ID. The fully qualified item ID is usually made up of the path to that server item in the tree, with each node name separated by a period char acter. In Figure 1-1, Example of OPC Server and Name Space, the fully qualified item ID for the highlighted server item might be

Area01.UnitA.FIC01.PV.

Most OPC servers provide a hierarchical name space, where server items are arranged in a tree-like structure. The tree can contain many different categories (called branch nodes), each with one or more branches and/or leaf nodes. A leaf node contains no other branches, and often represents a specific server Item. The fully qualified item ID of a server item is simply the ‘path’ to that leaf node, with a server-dependent separator.

Some OPC servers provide only a flat name space, where server items are all arranged in one single group. You could consider a flat name space as a name space containing only leaf nodes.

It is possible to convert a hierarchical name space into a flat name space. It is not always possible to convert a flat name space into a hierarchical name space.

1-5

1 Introduction

For information on how to obtain the name space of an OPC server, see “Browsing the OPC Server Name Space” on page 1-23.

Understanding the OPC Toolbox Object Hierarchy

OPC Toolbox software is implemented using three basic objects, designed to help you manage connections to servers and collections of server items. T he three objects are arranged in a specifi c hierarchy, shown in the following figure.

OPC Toolbox™ Object Hierarchy

1-6

1 OPC Data Access Client objects (opcda client objects)representa

specific OPC client instance that can communicate with only one server. You define the server using the

Host and ServerID properties. The Host

property defines the computer on which the server is installed. The

ServerID property defines the Program ID (ProgID) of the server, created

when the server was installed on that host. The

opcda client object acts as

a container for multiple group objects, and manages the connection to the server, comm unication with the server, and server name space browsing.

2 Data A

one o mana item of it

dag

3 Data Access Item objects (daitem objects) represent server items. Items

ccess Group o b je cts (

r more server items (data points on the server.) A

ges how often the items in the group must be read, whether historical

information m ust be stored, and also manages creation and deletion

ems. Groups cannot exist without an

roup

objects using the addgroup function of an opcda client object.

dagroup objects) represent containers for

dagroup object

opcda client object. You create

are defined by an item ID, which uniquely defines that server item in theserver’snamespace. A

TimeStamp, representing the information collected by the server from an

daitem object has a Value,aQuality,anda

Product Overview

instrument or data point in a SCADA system. The Value, Quality,and

TimeStamp properties represent the information known to the server when

theserverwaslastaskedtoaccessinformation from that instrument.

dagroup object can only exist “within” an opcda client object. Similarly, a

daitem object can only exist within a dagroup object. You create dagroup

objects using the addgroup method of an opcda client object. You create

daitem objects using the additem method of the dagroup object.

How OPC Toolbox Objects Relate to OPC Servers

OPC Toolbox software uses obje cts to define the server that the client must connect to, and the arrangement of items in groups. The following figure shows the relationship between the OPC Toolbox objects and an OPC server.

Figure 1-2: Relationship Between OPC Toolbox™ Objects and OPC Server

1-7

1 Introduction

The opcda client object establishes the connection between OPC Toolbox software and the O PC server, using OPC Data Access Specification standards. The standards are based on Microsoft COM/DCOM interoperability standards.

The

daitem objects represent specific server items. Note that a client typically

requires only a subset of the entire name space of a server in order to operate effectively. In Figure 1-2, Relationship Between OPC Toolbox™ Objects and OPC Server only the required for that particular group. Another group may only contain a single

daitem object, representing a single server item.

Note The dagroup obje ct has no equivalent on the OPC server. Howev er, the server keeps a record of each group that a client has created, and uses that group name to communicate to the client information about the items in that group.

PV and SP items of FIC01,andtheLIT01 item, are

System Requirements

OPC Toolbox s oftw are provides the Data Access client capabilities from within MATLAB. To use this toolbox functionality, you need access to an OPC server that supports the Data Access Specification version 2.05. In addition, you w ill need to ensure that you are able to connect to those OPC servers from the computer on which the toolbox software is installed. For more information on how to configure the client and server computers so that you can connect to an OPC server, see “Preparing to U se OPC Toolbox Software” on page 1-10.

1-8

Getting Command-Line Function Help

To get command-line function help, you can use the MATLAB help function. For example, to get help for the

help opcserverinfo

However, OPC Toolbox software provides “overloaded” versions of several MATLAB functions. That is, it provides toolbox-specific implementations of these functions using the same function name.

opcserverinfo function, type

Getting Command-Line Function Help

For example, the toolbox provides an overloaded version of the

isvalid

function. If you type

help isvalid

you get help for the MATLAB Timer object version of this function. You can determine if a function is overloaded by examining the last section of the help. For

isvalid, the help contains the following overloaded versions (not all

are shown).

Overloaded methods help serial/isvalid.m help instrument/isvalid.m. . . . help opcroot/isvalid.m

To obtain help on the toolbox version of this functio n, type

help opcroot/isvalid

To avoid having to specify which overloaded version you want to view, use the

opchelp function.

opchelp isvalid

You can also use this function to get help on OPC Toolbox object properties.

1-9

1 Introduction

Preparing to Use OPC Toolbox Software

In this section...

“Introduction” on page 1-10

“Installing the OPC Foundation Core Components” on page 1-10

“Configuring DCOM” on page 1-11

“Installing the Matrikon OPC Simulation Serv er” on page 1-18

Introduction

Before you can communicate with O PC servers on your network, you n eed to prepare your workstation (and possibly the OPC server host computer) to use the technologies on which OPC Toolbox software is built. These te chno log ies, describedin“AboutOPC”onpage1-3,allow you to browse for and connect to OPC servers on your network, and allow those OPC servers to interact with your MATLAB session using OPC Toolbox software.

1-10

The specific steps are described in the following sections.

Installing the OPC Foundation Core Components

The OPC Foundation has provided a set of tools for browsing other computers on your network for OPC servers, and for communicating with the OPC servers. These tools are called the OPC Foundation Core Components, and are shipped with OPC Toolbox software.

To install the OPC Foundation Core Components, you use the function. You can also use the opcregister function to remove or repair the OPC Foundation Core Components installation.

Installing, repairing, and removing the OPC Foundation Core Components follows the same steps:

1 If you are repairing o r removing the OPC Foundation Core Components,

make sure that you do not ha ve any OPC Toolbox objects in memory. Use the

opcreset function to clear all objects from memory.

opcreset;

opcregister

Preparing to Use OPC Toolbox™ Software

2 Run opcregister withtheactionyouwouldliketoperform. Ifyoudo

not supply an option, the function assumes that you want to install the components. Otherwise, use the files), or

opcregister('install')

3 YouwillbepromptedtotypeYe s to confirm the action you want to

'remove' to remove the components.

perform. You must type

'repair' to repair an installation (reinstall

Yes exactly as shown, without any quotes. This

confirmation question is used to ensure that you acknowledge the action that is about to take place.

4 The OPC Foundation Core Components will be installed, repaired, or

removed from your system.

5 If you receive a warning about having to reboot your computer, you must

quit MATLA B and restart your computer for the changes to take effect.

Configuring DCOM

DCOM is a client-server based architecture for enabling communication between two applications running on distributed computers. The OPC Data Access Specification utilizes DCOM for communication between the OPC client ( for example, OPC Toolbox software) and the OPC server. To successfully use DCOM, those two computers must share a common security configuration so that the two applications are granted the necessary rights to communicate with each other.

This section describes two typical DCOM configuration options to allow OPC Toolbox software to work. Other DCOM options might provide sufficient permissions for the toolbox to work with an OPC server; the options described here are known to work with tested vendors’ OPC servers.

There are two configuration types described in this section:

• “Configuring DCOM to Use Named User Security” on page 1-12 describes

how to provide security between the client and server negotiated on a dedicated named user basis. You do not have to be logged in as the named user in order to use this mechanism; all communications between the client and the server are performed using the dedicated named user, independently of the user making the OPC requests. However, the identity

1-11

1 Introduction

used to run the OPC server must be available on the client machine, and the p assword of that identity must match on both machines.

• “Configuring DCOM to Use No Security” on page 1-17 describes a

configuration that provides no security between the client and server. Use this option only if you are connecting to an OPC server on a dedicated, private netw ork. This configuration option has been known to cause some Microsoft Windows

You should use the named user configuration, unless your system administrator indicates that no security is required for OPC access.

Caution If your OPC server software comes with DCOM setup guidelines, you should follow the instructions provided by the OPC serv er vendor. The guidelines provided in this section are generic and may not suit your specific network and security model.

services to fail.

1-12

Note The following instructions apply to the Microsoft Windows XP operating system with Service Pack 2. Users of other M icrosoft Windows operating systemsshouldbeabletoadapttheseinstructionstoconfigureDCOMon their systems.

Configuring DCOM to Use Named User Security

To configure DCOM to use named user security, you will have to ensure that both the server machine and client machine have a common user who is granted DCOM access rights on both the server and client machines. You should consult the f oll owing sections for info rm ation on c onfiguring each machine:

• “OPC Server Machine Configuration” onpage1-13providesthestepsthat

you must perform on each of the machines providing OPC servers.

• “Client Machine Configuration” on page 1-14 provides the steps that you

must perform on the machine that will run MATLAB and OPC Toolbox software.

Preparing to Use OPC Toolbox™ Software

OPC Server Machine Configuration. On the machines hosting the OPC servers, perform the following steps:

1 Create a new local user. (You can also create a dom ain user if the server

and client machines are part of the same domain.) The name used in these instructions is

opc but you can choose any name, as long as you remain

consistent throughout these instructions.

2 Select Start > Settings > Control Panel.Double-clickAdministrative

Tools

and then double-click Component Services. The Component

Services dialog appears.

3 Browse to Component Services > Computers > My Computer > DCOM

Config

4 Locate your OPC server in the DCOM Config list. The example below shows

the Matrikon™ OPC Server for Simulation.

5 Right-click the OPC server object, and choose Properties.

6 In the General tab, ensure that the Authentication Level is set to Default.

7 In the Security tab, choose Customize for the Launch and Activation

Permissions, then click Edit. Ensure that the

opc user is granted local

Launch and Activation permissions.

1-13

1 Introduction

8 In the Security tab, choose Customize for the Access Permissions, then

click Edit. E nsure that the

9 In the Identity tab, select This user and type the name and password

for the

10 If the OPC server runs as a service, make sure that the service runs as the

opc user (created in step 1) and not as the system account.

11 Repeat s teps 4 through 10 for each of the servers you want to connect to.

opc user (created in step 1).

opc us er is granted local Access permissions.

Client Machine Configuration. On the machine(s) that will be running MATLAB and OPC Toolbox software, perform the following steps:

1 On the client machine(s), create the identical local user with the same

name and password permissions as you set up in step 1 of “OPC Server Machine Configuration” on page 1-13.

2 Select Start > Settings > Control Panel.Double-clickAdministrative

Tools

and then double-click Component Services. The Component

Services dialog appears.

1-14

3 Browse to Component Services > Computers > My Compu ter.Click

Configure My Computer in the Component Services toolbar as shown below.

Preparing to Use OPC Toolbox™ Software

4 Click the Default Properties tab, and ensure that Enable Distributed

COM is checked, and that the Default Authenticati on Level is set to

Connect and the Default Impersonation Level is set to Identify.

1-15

1 Introduction

5 Click the COM Security tab.

1-16

6 For t

7 For the Launch and Activation permissions, click Edit Default and ensure

he Access Permissions, click Edit Default and ensure that the is included in the Default Security list, and is granted both Local

user

ss and Remote Access permissions.

Acce

that the

opc user is included in the Default Security list, and is granted

opc

all rights (Local Launch, Remote Launch, Local Activation, and Remote Activation).

Preparing to Use OPC Toolbox™ Software

Your local client machine and server applications are now configured to use thesameusernamewhentheserverattempts to establish a connection back to the client.

Configuring DCOM to Use No Security

Caution You should not use this option if you are not in a completely trusted

network. Turning off DCOM security means that any user on the network can launch any COM object on your local machine. Consult with your network administrator before following these instructions.

You must complete the following steps on both the client and server machines.

1 Select Start > Settings > Control Panel.Double-clickAdministrative

Tools

Services dialog appears.

2 Browse to Component Services > Computers > My Computer.Click

the Configure My Computer button in the Component Services toolbar.

and then double-click Component Services. The Component

3 In the Default Properties tab, make sure that Enable Distributed COM

On T his Computer is selected. Select None as the Default Authentication Level, and Anonymous as the Default Impersonation Lev el.

4 In the COM Security tab, select Edit Limits from the Access Permissions

and ensure that

Everyone and ANONYMOUS LOGON are both granted Local

Access and R emote Access.

5 In the COM Security tab, select Edit Limits from the Launch and

Activation Permissions and ensure that

Everyone and ANONYMOUS LOGON

are both granted Local and Remote permissions (Local Launch, Remote Launch, Local Activation and Remote Activation).

Both the client and the server are now configured so that anybody can access any COM object on either machine.

1-17

1 Introduction

Caution This configuration is potentially dangerous in terms of security, and

is recommended for debugging purposes only.

Installing the Matrikon OPC Simulation Server

All examples in this guide and in the OPC Toolbox online help make use of a Matrikon demonstration server that you can download free of charge from:

http://www.matrikonopc.com

On that page, select Downloads > Product Software,thenselect MatrikonOPC Simulation Server Download.

Note You do not have to install the Matrikon OPC Simulation Server to enable any functionality of OPC Toolbox software. The Simulation Server is used purely for demonstrating the capabilities and syntax of OPC Toolbox commands, and for providing fully working example code.

1-18

To install the Matrikon OPC Simulation Server, follow the installation instructions with the software. When prompted for a server ID, use the standard server ID assigned to the Simulation Server (

'Matrikon.OPC.Simulation').

Exploring Available OPC Servers

In this section...

“Prerequisites” on page 1-19

“Determining Server IDs for a Host” on page 1-19

Prerequisites

To interact with an OPC server, OPC Toolbox software needs two pieces of information:

• The hostname of the computer on which the OPC server has been installed.

Typically the hostname is a descriptive term (such as an IP address (such as

• The server ID of the server you want to access on that host. Because a single

computer can host more than one OPC server, each OPC server installed on that computer is given a unique ID during the installation process.

192.168.2.205).

Exploring Available OPC Servers

'plantserver')or

Your network administrator will be able to provide you with the hostnames for all computers providing OPC servers on your network. You may also obtain a list of server IDs for each host on your network, or you can use the toolbox function in the following section.

opcserverinfo to access server IDs from a host, as described

Determining Server IDs for a Host

When an OPC serve r is installed, a unique server ID must be assigned to that OPC server. The server ID p rovides a unique name for a particular instance of an OPC server on a host, even if multiple copies of the same server software are installed on the same machine.

To determine the server IDs of OPC servers installed on a host, call the

opcserverinfo function, specifying the hostname as the only argument.

When called with this syntax, information about all the OPC servers available on that host.

info = opcserverinfo('localhost')

opcserverinfo returns a structure containing

1-19

1 Introduction

info =

Host: 'localhost'

ServerID: {1x4 cell}

ServerDescription: {1x4 cell}

OPCSpecification: {'DA2' 'DA2' 'DA2' 'DA2'}

ObjectConstructor: {1x4 cell}

The fields in the structure returned by opcserverinfo provide the following information.

Server Information Returned by opcserverinfo

Field Description

Host

Text string that identifies the name of the host. Note that no name resolution is performed on an IP address.

ServerID

Cell array containing the server IDs of all OPC servers accessible from that host.

1-20

ServerDescription

OPCSpecification

ObjectConstructor

Cell array containing descriptive text for each server.

Cell array containing the OPC Specification that the server provides. Currently, OPC Toolbox software supports only the

'DA2' specification.

Cell array containing default syntax you can use to create an OPC Data Access Client object associated with the server. See “Creating a Client Object” on page 1-21 for more information.

Connecting to OPC Servers

In this section...

“Overview” on page 1-21

“Creating a Cl ien t Object” on page 1-21

“Connecting a Client to the Server” on page 1-22

“Browsing the OPC Server Name Space” on page 1-23

Overview

After you get information about your OPC servers, described in “Exploring Available OPC Servers” on page 1-19, you can establish a connection to the server by creating an OPC Data Access Client ( that client to the server. These steps are described in the following sections.

Note To run the sample code in the following examples, you must have the Matrikon OPC Simulation Server available on your local machine. For information on installing this, see “Installing the Matrikon OPC Simulation Server”onpage1-18. Thecoderequiresonlyminorchangesworkwithother servers.

Connecting to OPC Servers

opcda) object and connecting

Creating a Client Object

To create an opcda object, call the opcda function specifying the hostname, and server ID. You retrieved this information using the function (described in “Exploring Available OPC Servers” on page 1-19).

This example creates an Matrikon OPC Simulation Server. The default

opcda syntax in the Objec tConstructor field.

da = opcda('localhost', 'Matrikon.OPC.Simulation.1');

opcda object to represent the connection to a

opcserverinfo function includes the

opcserverinfo

1-21

1 Introduction

Viewing a Summary of a Client Object

To view a summary of the characteristics of the opcda object you created, enter the variable name you assigned to the object at the command prompt. For example, this is the summary for the object

The items in this list correspond to the numbered elements in the object summary:

1 The title of the Summary includes the name of the opcda client object. The

default name for a client object is m ad e up of the can change the name of a client object using the “Configuring OPC Toolbox Object Properties” on page 3-17.

da.

'host/serverID'.You

set function, described in

1-22

2 The Server Parameters provide information on the OPC server that

the client is associated with. The host name, server ID, and connection status are provided in this section. You connect to an OPC server using the

connect function, described in “Connecting a Client to the Server”

on page 1-22.

3 The Object Parameters section contains information on the OPC Data

Access Group (

dagroup) objects configured on this client. You use group

objects to contain collections of items. Creating group objects is described in “Creating Data Access Group Objects” on page 3-2.

Connecting a Client to the Server

You connect a client to the server using the connect function.

connect(da);

Connecting to OPC Servers

Once you have connected to the server, the Status information in the client summary display will change from

If the clie n t could not connect to the server for some reason (for example , if the OPC server is shut down) an error message will be generated. For information on troubleshooting connections to an OPC server, see “Troubleshooting” on page 1-28.

Once you have connected the client to the server, you can perform the following tasks:

• Get diagnostic information about the OPC server, such as the server status,

last update time, and supporte d interfaces. You use the function to obtain this information. See opcserverinfo in the function reference for more information.

• Browse the OPC server name space for information on the available server

items. See “Browsing the OPC Server Name Space” on page 1-23 for det ails on browsing the server name space.

'disconnected' to 'connected'.

opcserverinfo

• Create group and item objects to interact with OPC server data. See

“Creating O PC Toolbox Objects” on page 3-2 for information on creating group and item obje cts.

Browsing the OPC Server Name Space

A connected client object allows you to interact with the OPC server to obtain information about the name space of that server. The server name space provides access to all the data points provided by the OPC server by naming each of the data points with a server item, and then arranging those server items into a name space that provides a unique identifier for each server item.

This section describes how you u se a connected client object to browse the name space and find information about each server item. These activities are described in the following sections:

• “Getting the S erver Name Space” on page 1-24 describes how to obtain a

server name space, or a partial server name space, using the and serveritems functions.

• “Getting Information about a SpecificServerItem”onpage1-26describes

howtoquerytheserverfortheproperties of a specific server item.

getnamespace

1-23

1 Introduction

Getting the Server Name Space

You use the getnamespace function to retrieve the name space from an OPC server. You must specify the client object that is connected to the server you are interested in. The name space is returned to you as a structure array containing information about each node in the name space.

The example below retrieves the name space of the Matrikon OPC Simulation Server installed on the local host.

da = opcda('localhost','Matrikon.OPC.Simulation.1'); connect(da); ns = getnamespace(da)

ns = 3x1 struct array with fiel ds:

Name FullyQualifiedID NodeType Nodes

1-24

The fields of the structure are described in the following table.

Field Description

Name

FullyQualifiedID

The name of the node, as a string.

The fully qualified item ID of the node, as a string. The fully qualified item ID is made up of the path to the node, concatenated with

'.' characters. You use the

fully q ualified item ID when creating an item object associated with th is node.

NodeType

Nodes

Thetypeofnode.NodeType can be 'branch' (contains other nodes) or

'leaf' (contains no other branches).

Child nodes. Nodes is a structure array with the same fields as

ns, representing the nodes contained in this

branch of th e name space.

From the example above, exploring the name space shows.

ns(1)

Connecting to OPC Servers

ans =

Name: 'Simulation Items'

FullyQualifiedID: 'Simulation Items'

NodeType: 'branch'

Nodes: [8x1 struct]

ns(3)

ans =

Name: 'Clients'

FullyQualifiedID: 'Clients'

NodeType: 'leaf'

Nodes: []

From the information above, the first node is a branch node c alled

'Simulation Items'. Since it is a branch node, it is most likely not a valid

server item. The third node is a leaf node (containing no other nodes) with a fully qualified ID of

'Clients'. Since this node is a leaf n ode, it is most likely

a server item that can be monitored by creating an item object.

To e xamine the nodes further down the tree, you need to reference the

Nodes

field of a branch node. For example, the first node contained within the

'Simulation Items' node is obtained as follows.

ns(1).Nodes(1)

ans =

Name: 'Bucket Brigade'

FullyQualifiedID: 'Bucket Brigade.'

NodeType: 'branch'

Nodes: [14x1 struct]

The returned result shows that the first node of 'Simulation Items' is a branch node named

ns(1).Nodes(1).Nodes(9)

ans =

FullyQualifiedID: 'Bucket Brigade.Real8'

'Bucket Brigade', and contains 14 nodes.

Name: 'Real8'

1-25

1 Introduction

NodeType: 'leaf'

Nodes: []

The ninth node in 'Bucket Brigade' is named 'Real8' and has a fully qualified ID of

'Bucket Brigade.Real8'. You use the fully qualified ID

to refer to that specific node in the server name space when creating items with OPC Toolbox software.

You can use the

flatnamespace function to flatten a hierarchical name space.

Getting Information about a Specific Server Item

In addition to publishing a name space to all clients, an OPC server provides information about the properties of each of the server items in the name space. These properties provide informationonthedataformatusedbythe server to store the server item value, a description of the server item, and additional properties configure d when the server item was created. The additional properties may include information on the range of the server item, the maximum rate at which the server can update that server item value, etc.

You access a property using a defined set of property IDs. A property ID is simply a number that defines a specific property of the server item. Property IDs are divided into three categories:

• OPC Specific Properties (1-99) that every OPC server must provide.

The OPC Specific Properties include the server item’s Value, Quality, and Timestamp. See “Understanding OPC Data: Value, Quality, and TimeStamp” on page 5-2 for more information on understanding OPC data.

• OPC Recommended Properties (100-4999) that OPC servers can provide.

These properties include maximum and minimum values, a description of the server item, and other commonly used properties. See Appendix B, “OPC Server Item Properties” for more information on OPC Recommended Properties.

1-26

• Vendor Specific Properties (5000 and higher) that an OPC server can

define and use. These properties may be different for each OPC server, and provide a space for OPC server manufacturers to define their own properties.

Connecting to OPC Servers

You query a server item’s properties using the serveritemprops function, specifying the client object, the fully qualified item ID of the server item you areinterestedin,andanoptionalvectorofpropertyIDsthatyouwishto retrieve. If you do not specify the property IDs, all properties defined for that server item are returned to you.

Note You obtain the fully qualified item ID from the server using the

getnamespace function or the serveritems function, which simply returns all

fully q ualified item IDs in a cell array of strings. See the function reference for more information on the

serveritems function.

The following example queries the Item Description property (ID 101) of the server item

'Bucket Brigade.ArrayOfReal8' from the example in “Getting

theServerNameSpace”onpage1-24.

p = serveritemprops(da, 'Bucket Brigade.ArrayOfReal8', 101)

PropID: 101

PropDescription: 'Item Description'

PropValue: 'Bucket brigade item.'

For a list of OPC Foundation property IDs, see Appendix B, “OPC Server Item Properties”.

1-27

1 Introduction

Troubleshooting

In this section...

“Introduction” on page 1-28

“Unable to Find an OPC Server” on page 1-28

““Class not registered” Error” on page 1-29

“UnabletoQuerytheServer”onpage1-29

“UnabletoConnecttoServer”onpage1-29

“Unable to Create a Group” on page 1-29

“Error While Querying Interface” on page 1-29

Introduction

If you are unable to establish a connection to an OPC server, the following sections might help you to identify problems with installation and configuration that could be preventing you from successfully querying and connecting to OPC servers.

1-28

Most problems with connecting to an OPC server relate to the DCOM settings on either the host or the client machine. For information on configuring DCOM, see “Configuring DCOM” on page 1-11.

Unable to Find an OPC Server

First, check that you are able to communicate with the host from your client. You can test this by attempting to run a Command P rompt and using the

'ping' command on the host. Alternatively, try to browse to the host using

the Network Neighborhood.

If you are able to communicate with the host, but you are unable to find an OPC server (using the Foundation Core Components may have to be reinstalled on your workstation. You can run the Components installation. For more information see “Installing the OPC Foundation C ore Components” on page 1-10.

opcserverinfo command) on that host, then the OPC

opcregister function to repair your OPC Foundation Core

Troubleshooting

“Class not regis

If you get this er or when attempti Core Component Foundation Cor Core Componen

Unable to Que

If you are una cause is inco section on “

Unable to C

An inabili model on th the DCOM c DCOM” on p

Unable t

If you ar common c the sec

eabletoconnecttotheserverbutcannotcreateagroup,themost

ause is incorrectly configured local DCOM security settings. Review

tion on “Configuring DCOM” on page 1-11.

ror while attempting to query a server using

ng to add a host in the OPC Tool GUI, the OPC Foundation

s have not been installed correctly. Install the OPC

e Components, as described in “Installing the O PC Foundation

ts” on page 1-10.

ry the Server

bletoquerytheserverusing

rrectly configured local DCOM security settings. Review the

Configuring DCOM” on page 1-11.

onnect to Server

ty to connect to the OPC server usually indicates that the security

e server is not allowing you to make an initial connection. Check

onfiguration on the server, and review the section on “Configuring

age 1-11.

o Create a Group

tered” Error

opcserverinfo,

opcserverinfo,themostcommon

Error W

If you objec

Error occurred while querying interface: IID_IOPCDataCallback

your

ect to the OPC Toolbox software client on the local machine. Review the

conn

tion on “Configuring DCOM” on page 1-11.

sec

hile Querying Interface

get this error while attempting to addagrouptoaconnectedclient

local DCOM security settings are not permitting the OPC server to

1-29

1 Introduction

1-30

Quick Start: Using the O PC Tool GUI

The best way to learn about the capabilities of O PC Toolbox software is to look at a simple example. This chapter illustrates th e basic steps required to log data from an OPC server for analysis and visualization. Th e example uses OPC Tool, a graphical user interface (GUI) provided in the toolbox, to demonstrate the process, and includes information on how to achieve the same results from the command line.

This chapter contains cross-references to other sections in the documentation that provide more in-depth discussions of the relevant concepts.

2 Quick Star t: Using the OPC Tool GUI

Example: Basic OPC Toolbox Acquisition Procedure

In this section...

“Overview” on page 2-2

“Step1: OpentheOPCToolGUI”onpage2-3

“Step 2: Locate Your OPC Server” on page 2-4

“Step 3: Create an OPC Data Access Client Object” on page 2-6

“Step 4: Connect to the OPC Server” on page 2-10

“Step 5: Create an OPC Data Access Group Object” on page 2-12

“Step 6: Browse the Server Name Space” on page 2-13

“Step 7 : Add OPC Data Access Items to the Group” on page 2-17

“Step 8: View All Item Values” on page 2-21

“Step9: ConfigureGroupProperties for Logging” on page 2-23

“Step 10: Log OPC Server Data” on page 2-25

2-2

“Step 11: Plot the Data” on page 2-26

“Step 12: Clean Up” on page 2-28

Overview

This section illustrates the basic steps required to create an OPC Toolbox application by visua li zing the Triangle Wave and Saw-toothed Wave signals provided with the Matrikon OPC Simulation Server. The application l ogs data to memory and plots that data, highlighting uncertain or bad data points. By visualizing the data you can more clearly see the relationships between the signals.

Example: Basic OPC Toolbox™ Acquisition Procedure

The example in this chapter uses the OPC Tool GUI. However, each step contains information on how to complete that step using command-line code. The entire example is contained in the demonstration file

opcdemo_quickstart.

Step 1: Open the OPC Tool GUI

To open the OPC Tool GUI, type opctool at the MATLAB prompt.

The GUI is displayed with no hosts, servers, or toolbox objects created. The following figure shows the main components of the OPC Tool GUI.

OPC Tool Graphical User Interface

In the following steps, you will fill each of the panes with information required to log data, and you will log the data, by creating and interacting with O PC Toolbox objects.

2-3

2 Quick Start: Using the OPC Tool GUI

Command-Line Equivalent

Since this step simply opens the OPC Tool GUI, there is no equivalent function when us ing the command line.

Step 2: Locate Your OPC Server

In this step, you obtain two pieces of information that the toolbox needs to uniquely identify the OPC server that you want to access. You use this information when you create an OPC Data Access Client object ( object), described in “Step 3: Create an OPC Data Access Client Object” on page 2-6.

The first piece of information that you require is the hostname of the server computer. The hostname (a descriptive name like " address such as is used by the OPC Data Access protocols to determine the available OPC servers on that computer, and to communicate with the computer to establish a connection to the server. In any OPC Toolbox application, you must know the name of the OPC server’s host, so that a connection with that host can be established. Your network administrator will be able to prov id e you with a list of hostnames that provide OPC servers on your network. In this example, you will use server on the same machine as the client.

opcda client

PlantServer"oranIP

192.168.16.32) qualifies that computer on the network, and

localhost as the hostname, because you will connect to the OPC

2-4

The second piece of information that you require is the OPC server’s server ID. E ach OPC server on a particular host is identified by a unique server ID

(also called the Program ID or ProgID), which is allocated to that server on installation. The server ID is a text string, usually containing periods.

Although your network administrator will be able to provide you with a list of server IDs for a particular host, you can query the host for all available OPC servers. “Exploring Available OPC Servers” on page 1-19 discusses how to query hosts from the command line.

Using the OPC Tool GUI you can browse a host using the following steps:

1 In the Hosts and OPC Servers pane, click the Add host icon to open

the Host name dialog, show n below.

Example: Basic OPC Toolbox™ Acquisition Procedure

Add Host Button and Resulting Host Name Dialog

2 In the Host name dialog, enter the name of the host. In this case, you can

use the "

localhost"alias.

localhost

Click OK. The hostname will be added to the OPC Network tree view, and the OPC servers installed on that host will automatically be found and added to the tree view. Your Hosts and OPC Servers pane should look similar to the one shown below.

Example of Hosts and OPC Servers Pane

te that the local host in this example provides three OPC server s . The

rver ID for this example is

'Matrikon.OPC.Simulation.1'.

2-5

2 Quick Start: Using the OPC Tool GUI

Command-Line Equivalent

The command-line equivalent for this step uses the function opcserverinfo.

hostInfo = opcserverinfo('localhost')

hostInfo =

ServerDescription: {1x3 cell}

OPCSpecification: {'DA2' 'DA2' 'DA2'}

ObjectConstructor: {1x3 cell}

Examining the returned structure in more detail provides the server IDs of each OPC server.

allServers = hostInfo.ServerID'

allServers =

'Matrikon.OPC.Simulation.1' 'ICONICS.Simulator.1' 'Softing.OPCToolboxDemo_ServerDA.1'

Host: 'localhost'

ServerID: {1x3 cell}

2-6

Step 3: Create an OPC Data Access C lient Object

Once you have determined the hostname and server ID of the OPC server you want to connect to, you can create an the connection status to the server, and stores any e ve nts that take place from that server (such as notification of data changing state, which is called a data change event) in the event log. The Data Access Group objects that you create on the client. For more information on the OPC Toolbox object hierarchy, see “Understanding the OPC Toolbox Object Hierarchy” on page 1-6.

With the OPC Tool GUI, you can create a client directly from the Hosts and OPC Servers pane.

Right-click the

Matrikon server node and choose Create client.Aclientwill

be created in the OPC Toolbox Objects pane, as shown in the following figure.

opcda client object. The client controls

opcda client object also contains any

Example: Basic OPC Toolbox™ Acquisition Procedure

Server Context Menu and Client Node

The name of the client (displayed in the OPC Toolbox Objects pane) is

Host/ServerID,whereHost is the hostname and ServerID is the Server

ID associated with that client. In this example, the client’s name is

'localhost/Matrikon.OPC.Simulation.1'

2-7

2 Quick Start: Using the OPC Tool GUI

Once you have created the client, you can view the properties of the client object in the Object Properties pane, as shown in the next figure.

2-8

Example of OPC Toolbox Objects P ane, Showing Client Properties

Alternative Methods for Creating Clients

You can also create a client in the OPC Tool GUI by using one of the followin g methods:

• Select the MATLAB OPC Clients node in the OPC Toolbox Objects

pane and click Add Client in the OPC Toolbox Objects toolbar.

• Choose Add from the Client menu.

• Right-click the MATLAB OPC Clients node in the OPC Toolbox Objects

tree and select Create Client.

Example: Basic OPC Toolbox™ Acquisition Procedure

If you select one o f the m e thods described above, a dialog appears requesting thehostnameandserverID.

Add Client Dialog

When you supply a hostname, you will be able to select the Server ID from a list, by clicking Select. Using the Add client dialog, you can also automatically attempt to connect to the server when the client is created, by checking Connect after creating OPC Client before clicking OK.

Command-Line Equivalent

The command-line equivalent of this step involves using the opcda function, specifying the hostname and Server ID arguments.

da = opcda('localhost', 'Matrikon.OPC.Simulation.1')

da =

OPC Data Access Object: localhost/Matr ikon.OPC.Simulation.1

Server Parameters

Host: localhost ServerID: Matrikon.O PC.Simulation.1 Status: disconnected

Object Parameters

Group: 0-by-1 dagroup object

For more information on creating clients, see “Creating a Client Object” on page 1-21.

2-9

2 Quick Start: Using the OPC Tool GUI

Step 4: Connect t

OPC Data Access C when they are cre object hierarc server, or with

Note The Add Cl Clients” on p client objec

To connect t toolbar, sh

age 2-8 can connect the client to the server after creating the

he client to the server, you can use the OPC Toolbox Objects

own in the follow ing figure.

lient objects are not automatically connected to the server

ated. This allows you to fully configure an OPC Toolbox

hy (a client with groups and items) prior to connecting to the

out a server even being present.

ient dialog described in “Alternative Methods for Creating

otheOPCServer

2-10

OPC Too

Click conne tree w conne See “ be ab

lbox Objects Toolbar

Connect in the OPC Toolbox Objects toolbar. If the client is able to ct to the server, the icon for that client in the OPC Toolbox Objects

ill change to show that the client is connected. If the client could not

ct to the server, an error dialog will show any error message returned.

Troubleshooting” on page 1-28 for information on why a client may not

le to connect to a server.

Example: Basic OPC Toolbox™ Acquisition Procedure

When you connect an opcda client object to the server associated with that client, the server node in the Hosts and OPC Servers pane also updates to show that the server has a connection to a client in the GUI. With that connection, the properties of the server are displayed in the Hosts and OPC Servers pane. For this example, a typical view of the GUI afte r connecting to a client is shown in the next figure.

Example of Connected Client and OPC Server Properties

The OPC server properties include diagnostic information, such as the supported O P C Data Access interfaces, the time the server was started, and the current server status.

Command-Line Equivalent

You use the connect function to connect an opcda client object to the server at the command line.

connect(da)

2-11

2 Quick Start: Using the OPC Tool GUI

Step 5: Create an

You create Data A acollectionofD controls how of values, contro start, and sto

To create a toolbar. A gr server or by O

dag

ccess Group objects (

ata Access Item objects (

tentheservermustnotifyyouofanychangesintheitem

l the activation status of the items in that group, and define,

p logging tasks.

roup

object, click Add group in the OPC Toolbox Objects

oup is created and automatically named, either by the OPC

PC Toolbox software.

OPC Data Access Group Object

dagroup objects) to control and contain

daitem objects). A dagroup object

2-12

Example of OPC Data Access Group Properties Pane

On their own, dagroup objects are not useful. Once you add items to a group, you can control thos e items, read values from the server for all the items in a group, and log data for those items, using the

dagroup object. In Step 6 you

Example: Basic OPC Toolbox™ Acquisition Procedure

browse the OPC server for available tags. Step 7 involves adding the items associated with those tags to the

dagroup object.

Command-Line Equivalent

To create dagro up objects from the command line, you use the addgroup function. This example adds a group to the opcda client object already created.

grp = addgroup(da)

grp =

OPC Group Object: Group0

Object Parameters

GroupType: private Item: 0-by-1 daitem object Parent: localhost/Matrikon.OPC.Simulation.1 UpdateRate: 0.5 DeadbandPercent: 0

Object Status

Active: on Subscription: on Logging: off LoggingMode: memory

See “Creating Data Access Group Objects” on page 3-2 for more inform ation on creating group objects from the command line.

Step 6: Browse the Server N ame Space

All OP C servers provide access to server items via a server name space. The name space is an ordered list of the server items, usually arranged in a hierarchical format for easy access. A server item (also known as a tag)isa measurement or data point on a server, providing information from a dev ice (such as a pressure sensor) or from another software package that supplies data through OPC Data Access (such as a SCADA package).

2-13

2 Quick Start: Using the OPC Tool GUI

Note If you know the item IDs of the server items you are interested in, you

can skip this section and proceed to “Step 7: Add OPC D ata Access Items to the G roup” on page 2-17. In this example, assume that you d o not know the exact item IDs, although you do know that you want to log information from the Saw-toothed Waves and Triangular Waves provided by the Matrikon Simulation Server.

The Namespace tab of the Hosts and Servers pane allows you to graphically browse a server’s name space. Because most OPC servers contain thousands of server items, retrieving a name space can be time consuming. When you connect to a server for the first time, the name space is not automatically retrieved.YouhavetorequestthenamespaceusingoneoftheView buttons in the Server Namesp ace toolbar, as shown in thefollowingfigure.

2-14

Namespace Toolbar Showing View Buttons

Click View hierarchical namespace to retrieve the hierarchical name space for the Matrikon OPC Server. A tree view containing the Matrikon name space is shown in the pane. Your pane should look similar to the following figure.

Example of Populated Namespace Tree

Example: Basic OPC Toolbox™ Acquisition Procedure

Note If you choose to view the name space as flat, you get a single list of all server items in the name space, expanded to their fully qualif ied names. A fully q ualified name can be used to create a

daitem object.

BrowsingthenamespaceusingtheGUIalsoprovidessomeproperty information for each server item. The properties include the published OPC Item properties such as Value, Quality, and Timestamp, plus additional properties published by the OPC server that may provide more information on that particular server item. For a list of standard OPC properties and an explanation of their use, consult Appendix B, “OPC Server Item Properties”.

In this example, you need to locate the Saw-toothed Waves and Triangle Waves signals in the Matrikon Simulation Server. You can achieve this using the following steps:

1 Ensure that you are viewing the hierarchical name space.

2 Expand the Simulation items node. You will see all the signal types

that the Matrikon Server simulates.

3 Expand the Saw-toothed Waves node. A number of leaf nodes appear. A

leaf node contains no other nodes, and usually signifies a tag on an OPC server.

2-15

2 Quick Start: Using the OPC Tool GUI

4 Select the Real8 leaf node. You will see the properties of the server item in

thepropertiestablebelowthenamespace tree, as shown in the following figure.

2-16

Example o

f Server Tag Properties

Note the Item Canonical DataType property, which is double.The Canonical DataType is the data type that the server uses to store the server item’s value.

5 Select the UInt2 leaf node. You will notice that the properties update, and

the

Item Canonical Datatype property for this server item is uint16.

(MATLAB denotes integers with the number of bits in the integer, such as

uint16; the Matrikon Server uses the COM Variant convention denoting

the number of bytes, such as

UInt2.)

You can continue browsing the server name space using the Server Namespace pane in the GUI. One unique characteristic of the Matrikon

Simulation Server is that you can view the connected clients through the name space, by selecting the Clients node in the root of the name space.

In Step 7, you will add three items to your newly created group object, using the Server Namespace pane.

Example: Basic OPC Toolbox™ Acquisition Procedure

Command-Line Equivalent

From the command line, you can “browse” the server name space using the

serveritems function. Y ou need to supply a connected opcda client object

to the results. The string can contain wildcard characters (

serveritems is as follows.

serveritems function, and an optional string to limit the returned

*). An example of using

sawtoothItems = serveritems(da, '*Saw*')

sawtoothItems =

'Saw-toothed Waves.' 'Saw-toothed Waves.Int1' 'Saw-toothed Waves.Int2' 'Saw-toothed Waves.Int4' 'Saw-toothed Waves.Money' 'Saw-toothed Waves.Real4' 'Saw-toothed Waves.Real8' 'Saw-toothed Waves.UInt1' 'Saw-toothed Waves.UInt2' 'Saw-toothed Waves.UInt4'

The command-line equivalent for obtaining the server item properties is

serveritemprops.Seetheserveritemprops reference page for more

information on using the function.

Step 7: Add OPC Data Access Items to the Group

Now that you have found the server items in the name space, you can add Data Access Item objects ( you created in Step 5. A providing the tag value, and additional information on that item, such as the Canonical Data Type.

Using the GUI, you create items directlyfromthenamespacetree,usinga contextmenuoneachnodeinthetree.

Browse to Simulated Items > Saw-toothed Waves > Real8, and right-click that node to bring up the context menu. Selecting Add to from the context menu provides you with a list of created groups for the item associated with

daitem object) for those tags to the dagroup object

daitem object is a link to a tag in the name space,

2-17

2 Quick Start: Using the OPC Tool GUI

that server, and a menu item to create a New group (and add the item to that group).

The menu displayed for this example is shown in the following figure.

Example of Context Menu for Namespace Node

Click Group0 to add the item to the already existing group that you created in Step 5. A following figure shows the newly created item highlighted, with the properties of the item shown in the Properties pane.

daitem object is created in the OPC Toolbox Objects pane. The

2-18

Example: Basic OPC Toolbox™ Acquisition Procedure

Example of Data Access Item Object and Properties

Reading a Value from the Server

A d aite m object initially contains no information about the server item that it represents. The of a change in status for that item (the notification is called a data change event) or the client specifically reads a value from the server. Using the GUI, you can force a read of the item by clicking Read in the Properties pane of the required item.

Click Read.TheValue, Quality,andTimestamp fields in the GUI will update. Value contains the last value that the server read from that particular item. Quality provides a measure of how meaningful Value is. If Quality is device or object to which the item refers, but only at the time provided by the Timestamp field. If Quality is anything othe r than of the item is questionable.

daitem object only updates when the server notifies the client

Good, then the Value can be trusted to be the same as the

Good,thentheValue

2-19

2 Quick Start: Using the OPC Tool GUI

Each time you read or obtain data from the server through a data change event, the server will provide you w ith updated Value, Quality, and Timestamp values.

Adding More Items to the Group

Using the Namespace pane, e xpand the Triangle Waves node and add items for the Real8 and UInt2 server items. You will then have three items associated with your session for that group. You then log data in Step 9 from the three items you just created, and visualize the data in Step 10.

Command-Line Equivalent

You use the additem function to add items to a dagroup object. You need to pass the qualified item ID as a string. The item IDs were found using the function in Step 6.

itm1 = additem(grp, 'Saw-toothed Waves.Real8')

dagroup object. In Step 8, you configure a logging

dagroup object to which the items will be added, and the fully

serveritems

2-20

itm1 =

OPC Item Object: Saw-toothed Waves.Real8

Object Parameters

Parent: Group0 AccessRights: read/write DataType: double

Object Status

Active: on

Data:

Value: Quality: Timestamp:

You can add multiple items to the group in one additem call, by specifying multiple

ItemID values in a cell array.

itms = additem(grp, {'Triangle Waves.Real8', ... 'Triangle Waves.UInt2'})

itms =

Example: Basic OPC Toolbox™ Acquisition Procedure

OPC Item Object Array: Index: DataType: Act ive: ItemID: 1 double on Triangle Waves.Real8 2 uint16 on Triangle Waves.UInt2

For more information on adding items to groups, see “Creating Data Access Item Objects” on page 3-5.

Step 8: View All Item Values

You can view the Value, Quality, and Timestamp for each item using the item’s properties pane. However, that view only provides access to one item at a time. The group object is designed to allow you to read and write values from all items in the group, and to log data to memory and/or d isk. You use the Group R ead/Write pane to view the values of the items you created in Step 7 to determine the approximate range of values that each item’s value varies over. The information from this pane will help you to verify that the data is updating, and whether you can plot the data in one set of axes or in subplots.

Click Group0 in the OPC Toolbox Objects pane. Select the Read/Write tab in the top of the Group properties pane. The OPC Toolbox Objects pane should now look similar to the one shown in the following figure.

2-21

2 Quick Start: Using the OPC Tool GUI

Example of Group Read/Write Pane

The Value, Quality,andTimestamp values in the table of items will continually update as long as you have Subscription enabled. Subscription controls whether data change events are sent by the OPC server to the toolbox, for items whose values change. define how often the items must be queried for a new value, and whether all value changes or only changes of a specified magnitude are sent to the toolbox. For more information on Subscription, see “Data Change Events and Subscription” on page 4-12.

By observing the data for a while, you will see that the three signals appear to have similar ranges. This indicates that you can visualize the data in the same axes when you plot it in Step 11.

2-22

UpdateRate and DeadbandPercent

Example: Basic OPC Toolbox™ Acquisition Procedure

You can also use the Group Read/Write pane for writing values to many items simultaneously. Specify a value in the Write column of the Item data table for each item you want to write to, and click Write,tobeableto write to those items.

In Step 10 you will configure a logging task and log data for the three items.

Command-Line Equivalent

You can use the read function with a group object as the first parameter to read values from all items in a group. The detail in “Reading and Writing Data” on page 4-2.

read functio n is discussed in more

Step 9: Configure Group Properties for Logging

Now that your d agr oup object contains items, you can use the group to control the interaction of those items w ith the server. In this step, you configure the group to log data from those items for 2 minutes at 0.2-second intervals. You will use the logged data in Step 11 to visualize the signals produced by the Matrikon Simulation Server.

OPC Data Access Servers provide access only to "live" data (the last known value of each server item in their name space). In many cases, a single value of a signal is not useful, and a time series containing the signal value over a period of time is helpful in analyzing that sig nal or signal set. OPC Toolbox software allows you to log all items in a group to disk or memory, and to retrieve that data for analysis in MATLAB.

You configure a logging session using the properties associated with logging, you control how often the data must be sent from the server to the client, how many records the group must log, and where to log the data. This information is summarized in the Logging pane of the

dagroup object properties in the GUI.

dagroup object. By modifying the

2-23

2 Quick Start: Using the OPC Tool GUI

Select the Logging tab in the Properties pane. The following figure shows the Logging pane for the

dagroup object created in this example.

2-24

Example of Logging Pane for Data Access Group Objects

Using the Logging pane, configure the logging session using the following steps:

1 Set Update rate to 0.2.

2 Set Number of records to log to 600.Becauseyouwanttologfor

2 minutes (120 seconds) at 0.2-second update rates, you need 600 (i.e., 120/0.2) records.

You can leave the rest of the logging properties at their default values, because this example uses data logged to memory.

In Step 10 you log the data. In Step 11 you will visualize the data.

Example: Basic OPC Toolbox™ Acquisition Procedure

Command-Line Equivalent

You use the set function to set OPC Toolbox object properties. From the MATLAB command line, you can calculate the number of records required for the logging task.

logDuration = 2*60; logRate = 0.2; numRecords = ceil(logDuration./logRate) set(grp, 'UpdateRate',logRate,'RecordsToAcquire',numRecor ds);

Step 10: Log OPC Server Data

In Step 9 you configured the dagroup object’s logging properties. Your object is now ready to log the required amount of data to memory.

Click Start in the Logging tab. The logging task will begin, and the OPC Toolbox software engine will receive and store the data from the OPC server. Theprogressbarindicatesthestatusoftheloggingtask,asshowninthe following figure.

Example of Logging Task in Progress

Note The logging task occurs in the background. You can continue working

in MATLAB while a logging task is in operation. The logging task is not affected by any other computation taking place in MATLAB, and MATLAB is not blocked from processing by the logging task.

Wait for the task to complete before continuing with Step 11.

Command-Line Equivalent

You use the start function with the required dagroup object to start a logging task.

2-25

2 Quick Start: Using the OPC Tool GUI

start(grp)

Although the logging operation takes place in the background, you can instruct MATLAB to wait for the logging task to complete, using the function.

wait(grp)

Step 11: Plot the Data

In this introducto ry example, you use the GUI to visualizethedatalogged in Step 10. In a more complex task, you would export the logged data to the workspace and use MATLAB functions to analyze and interpret the logged data.

When the logging task stops, the Logging pane will update to show that the task is complete. An example of the logging status portion of the Logging pane after a completed task is shown in the following figure.

wait

2-26

Exampl

To vie from t forma in the be an Valu bord You s det Val Val

e of Logging Pane After Logging has Completed

w the data from the GUI, click Plot. The logged data will be retrieved he toolbox engine and displayed in a MATLAB figure window. The

t of the displayed data and annotation options are controlled by settings

Plot options frame of the Logging pane. By default, the plot will

notated with a ny data points that have a Quality other than

es whos Quality is

er, a nd Values with Quality of

hould always view the Quality returned with the Value of an item to

ermine if the Value is meaningful or not. The relationship between the

ue and Quality of an item is discussed in “Understanding OPC Data: ue, Quality, and TimeStamp” on page 5-2.

Bad are annotated with a large red circle with a black

Repeat are annotated with a yellow star.

Good.

Example: Basic OPC Toolbox™ Acquisition Procedure

An example of the plotted data is shown in the next figure.

Example of Data Plot from a Logging Task

Note Your plotted data will almost certainly not l ook like the one shown here,

because the logging task was executed at a different time.

Notice how the three signals seem almost completely unrelated, except for the period of the two Real8 signals. The peak values for each signal are different, as are the periods for the two Triangle Waves signals. By visualizing the data,youcangainsomeinsightintothewaytheMatrikonOPCSimulation Server simulates each tag. In this case, it is apparent that

Real8 and UInt2

signals have a different period.

mand-Line Equivalent

Com

When your logging task has completed you transfer data from the toolbox engine to the MATLAB workspace using the

getdata function, which provides

2-27

2 Quick Start: Using the OPC Tool GUI

two types of output, depending on the ’datatyp e’ argument. For more information see data into separate arrays, and plot the data.

The example below reproduces the figuredisplaythatyougetwhenyouclick Plot.

[logIDs, logVal, logQual, logTime, lo gEvtTime] = ...

getdata(grp, 'double'); plot(logTime, logVal); axis tight datetick('x', 'keeplimits') legend(logIDs)

Step 12: Clean Up

When you are finished with an OPC task, you should remove the task objects from memory and clear the MATLAB workspace of the variables associated with these objects. The OPC Tool GUI will automatically delete all objects that it creates from the toolbox engine. If you work only in the OPC Tool GUI, you do not need to perform any further cleanup other than to close the GUI. You close the GUI by using the Exit option in the File menu, or by using the Close button in the title bar. You will be prompted to save the OPC Tool session. You can choose to save the ses sio n to an OPC Session File ( for later use, or exit without saving.

getdata in the reference pages. In this case you retrieve the

.osf file)

2-28

Command-Line Equivalent

When you use OPC Toolbox objects from the MATLAB command line, or from your own functions, you must remove them from the OPC Toolbox software engine using the the children of that object are automatically removed from the toolbox engine. In the following example, there is no need to delete are children of

disconnect(da) delete(da) clear da grp itm close(gcf)

delete function. Note that when you delete a toolbox object,

grp and itm,asthey

da.

Example: Basic OPC Toolbox™ Acquisition Procedure

OPC Toolbox object management is discussed in more detail in “D eleting Objects” on page 3-23.

2-29

2 Quick Start: Using the OPC Tool GUI

2-30

Using OPC Toolbox Objects

To interact with an OPC server, you need to create toolbox objects. You create an OPC Data Access Client ( a particular OPC server. You then create one or more Data Access Groups (

dagroup objects) to control sets of Data Access Items (daite m objects), w hich

represent links to server items. OPC Toolbox objects are described in more detail in “Understanding the OPC Toolbo x Object Hie rarchy ” on page 1-6.

This chapter describes how to create and configure toolbox objects to interact with an OPC server. Chapter 4, “Reading, Writing, and Log gin g OPC Data” provides information on how to use the OPC Toolbox objects to exchange data with an OPC server.

opcda client) object to provide a connection to

• “Creating OPC Toolbox Objects” on page 3-2

• “Configuring OPC Toolbox Object Properties” on page 3-17

• “Deleting Objects” on page 3-23

• “Saving and Loading Objects” on page 3-25

3 Using OPC Toolbox™ Objects

Creating OPC Toolbox Objects

In this section...

“Overview” on page 3-2

“Creating Data Access Group Objects” on page 3-2

“Creating Data Access Item Objects” on page 3-5

“Building an Object Hierarchy with a Disconnected Client” on page 3-8

“Creating O PC Toolbox Object Vectors” on page 3-9

“Working with Public Groups” on page 3-12

Overview

The f irst step in intera ctin g with an OPC server from MATLAB software is to establish a connection between the server and OPC Toolbox software. You create and the toolbox. Then you create objects, and then you create the daitem objects themselves, which represent server items. A server item corresponds to a physical device or to a storage location in a SCADA system or DCS.

opcda client objects to control the connection between an OPC server

dagroup objects to manage sets of daitem

3-2

You m ust create the toolbox objects in the order described above. “Connecting to OPC Servers” on page 1-21 describes how to create an This section discusses how to create and configure objects.

opcda client object.

dagroup and daitem

Creating Data Access Group Objects

Once you have created an opcda client object, you can add groups to the client. A

dagroup object manages multiple daitem objects. Using a dagroup object,

you can read data from all items in that group in one action, w rite data to the items in the group, define actions to take when any of the items in that group change value, or log data for all the items in that group for analysis and processing.

To create a

opcda client object that you want to add the group to, and an optional group

dagroup object, you use the addgroup function, specifying the

Creating OPC Toolbox™ Objects

name. See “Specifying a Group Name” on page 3-3 for rules on defining your own group name.

The example below creates an

opcda client object, connects that object to the

server, and adds two groups to the client. The first group is automatically named by the server, and the second group is given a specified name.

da = opcda('localhost', 'Matrikon.OPC.Simulation.1'); connect(da); grp1 = addgroup(da); grp2 = addgroup(da, 'MyGroup');

Specifying a Group Name

Every OPC server requires that each group created by the client has a unique name. This allows the OPC server to uniquely identify the group when a client makes a server request using that group. The name can be any nonempty string.

You do not need to specify a group name for each group that you add to a client. If you do not specify a name, the OPC server will automatically assign a group name for you. Each OPC server defines different rules for automatic naming of groups.

If you attempt to create a group with the same name as a group already created for that client, an error will be generated.

See “Deleting Objects” on page 3-23 for information about how groups are automatically named when you create groups with a disconnected client.

Viewing a Summary of a Group Object

To view a summary of the characteristics of the dagroup object you created, enter the variable name you assigned to the object at the command prompt. For example, this is the summary for the object

grp1

grp1.

3-3

3 Using OPC Toolbox™ Objects

The items in this list correspond to the numbered elements in the object summary:

3-4

1 The title of the Summary includesthenameoftheda group object. In the

example, this is the server-assigned name

2 The Object Parameters section lists the v a lues of key dagroup object

properties. These properties describe the ty pe of group, the associated with the group, the name of the group’s parent

Group0.

daitem objects

opcda client

object, and properties that control how the server updates item information for this group. In the example, any items created in this group w ill be updated a t half-second intervals, with a deadband of 0%. For information on how the server updates item information, see “Data Change Events and Subscription” on page 4-12 .

3 The Object Status section lists the current state of the object. A dagroup

object can be in one of several states:

• The

Active state defines whether any operation on the group applies

to the item.

• The

Subscription state defines whether changes in the item’s value or

quality will produce a data change event. See “Data Change Events and Subscription” on page 4-12 for more information about the

Subscription

property.

Creating OPC Toolbox™ Objects

• The Logging sta t e describes whether the group is logging or not. See

“Logging O PC Server Data” on page 4-17 for information on how to log data.

4 The Logging Paramet ers section describes the values of the logging

properties for that group. Logging properties control how the

dagroup

object logs data, including the duration of the logging task and the destination of logged data. See “Logging OP C Server Data” on page 4-17 for information on logging data using

dagroup objects.

Using a Group Object

A dagroup object with no items does not perform any useful functions. Once youhaveaddeditemstoagroup,youcanusethegroupto

• Read data from, and write data to, the OPC server. See “Reading and

Writing D ata” on page 4-2 for more information.

• Control how an OPC server notifies MATLAB about changes in any

item associated with a Subscription” on page 4-12 for more information.

dagroup object. See “Data Change Events and

• Log data from all items in that group, for later processing and analysis.

“Logging OPC Server Data” on page 4-17 describes how to control logging.

Creating Data Access Item Objects

A dagroup object provides a container for collecting one or more daitem objects. A daitem object provides a link to a specific server item. The daitem object defines how you want to retrieve and store the client-side value of the server item, and also stores the last data retrieved from the server for that server item. You can use a server item, or to write values to that server item on the server.

You create a

daitem object using the additem function, specifying the dagroup

object to which the item must be added and the fully qualified item ID of the server item. You can obtain a list of the fully qualified item IDs for all server items using the

serveritems function.

The example below builds on the example in “Creating Data Access Group Objects” on page 3-2 by adding a

daitem object to read data from the server for that

daitem object to the first group created

3-5

3 Using OPC Toolbox™ Objects

in that example. The server item associated with this item is called

'Random.Real8'.

itm1 = additem(grp1, 'Random.Real8');

Specifying a Local Data Type for the Item

When you create a daitem object, you create an object that stores the value of the server item locally on the client. You can specify that the local storage data type be different from the server storage data type. For example, you can specify that a value stored on the server as an integer be stored in MATLAB as a double-precision floating-point value, because you know that you will be performing double-precision calculations with that item’s value.

Although it is possible to modify the data type of the item after it is created, you can also create an item with a specific data type by specifying the data type as the third parameter to the specification must be a string describing that data type. Valid OPC data types are any MATLAB numeric data type, plus “Working with Different Data Types” on page 5-18 for more information on supported data types.

additem function. The data type

'char',and'log ica l'.See

3-6

The example below adds another item to the group

grp1 created by the

example in “Creating Data Access Group Objects” on page 3-2. The item ID is

'Random.UInt2', which is stored on the server as an unsigned 16-bit

integer. By specifying the data type as

'double', the value will be returned

to MATLA B and stored locally as a double-precision floating-point number.

itm2 = additem(grp1, 'Random.UInt2', 'double');

Note The conversion process from the server’s data type to the item’s data type is performed by the server, using Microsoft COM Variant conversion rules. If you attempt to convert a value to a data type that does not have that value’s range, the OPC server will return an error when attempting to update thevalueofthatitem.Youshouldthenchangethedatatypetoonethathas the same or larger range than the server item’s data type. See “W orking with Different Data Types” on page 5-18 for more information.

Creating OPC Toolbox™ Objects

Specifying the Active Status of an Item Object

You can optionally specify the Active status of an daitem object by passing a string as the fourth parameter to the can be

'on' or 'off'. AnitemwithanActive status of 'off' behaves as if

additem function. The Active status

the item was never created: No server updates of the item’s value will take place, and a read or write with that item will fail. You use the

Active status

to temporarily disable an item without deleting that item from MATLAB. For more information on the

Active property.

Active status, see the reference page for the

Viewing a Summary of the Item Object

To view a summary of the characteristics of the daitem object you created, enter the variable name you assigned to the object at the command prompt. For example, this is the summary for the object

itm1

itm1.

The items in this list correspond to the numbered elements in the object summary:

1 The title of the Summary includes the fully qualified item ID of the item . In

the example, the item is associated with the

2 The Object Parameters section lists the values of key daitem object

properties. These properties describethenameoftheitem’s and the

Access Rights advertised by the server.

'Random.Real8' server item.

Parent group,

3-7

3 Using OPC Toolbox™ Objects

3 The Object Status section lists the Active state of the object. The Active

state defines whether any operation on the parent group applies to the item, and whether you want to be notified of any cha nges in the item’s value.

4 The Data Parameters section lists the Data Type used by the daitem

object to store the value, and the Value, Quality,andTimeStamp of the last value obtained from the server for this item. For more information on the Data: Value, Quality, and TimeStamp” on page 5-2.

Using an Item Object

You create a daitem object to query the value of the associated server item, or to write values to that server item. You can write values to a single item, and read value s from a single item, using the on reading and writing values, see “Reading and Writing Data” on page 4-2.

Value, Quality,andTimeStamp of an item, see “Understanding OPC

daitem object. For more information

You can also use the parent of the

daitem objects contained in that group, or to log changes in the item’s

value for a period of time. See “Logging OP C Server Data” on page 4-17 for information on logging data.

dagroup object to read and write values for all

Building an Object Hierarchy with a Disconnected Client

When you create objects with a connected client, OPC Toolbox software validates those objects with the OPC server before creating them on the client. For example, wh en adding a group to the client using the function, the validation process ensures that no other group with the same name exists on the server, and that the server will accept the group. When adding an item, the item ID is verified to be a valid server item.

Occasionally you may wish to build up a toolbox object hierarchy without connecting to the server. For example, you may be off site and wish to configure a logging task for use on the following day, rather than wait to configure the objects for that task when you are on site.

OPC Toolbox software allows you to configure an entire toolbox object hierarchy without connecting to the server. However, without a connection to the server, the toolbox cannot validate the created objects with that server.

addgroup

3-8

Creating OPC Toolbox™ Objects

Instead, OPC Too lbox software will perform some basic validation on the objects you create, and revalidate those objects with the server when you connect to the server.

When you create toolbox objects with a d isco nnected client, the fo ll owing validation is performed:

• When adding a group using the

addgroup function, if you do not specify

a name, OPC Toolbox software automatically assigns a unique name

'groupN',whereN is the lowest integer that ensures that the group name

is unique. For example, the first group created will be

'group2',andsoon.

• When you specify a group name when using the

'group1',then

addgroup function, an

error will be generated if a group with the same name already exists.

• When adding an item to a group using the

additem function, an error will

be generated only if an item with the same name already exists in that group. No other checking is performed on the item.

• When adding an item to a group, if you do not specify a data type for that

item, the data type is set to the data type will be changed to the server item’s

'unknown'. When you connect to the server,

CanonicalDataType.

Despite all of the checks described above, the server may not accept all objects created on a disconnected client when that client is connected to the server using the

connect function. For example, an item’s item ID may n ot

be valid for that server, or a group name may not be valid for that server. When you connect a client to the server using

connect, any objects that the

server rejects will be deleted from the object hierarchy, and a warning will be generated. In this way, all objects on a connected client are guaranteed to have been accepted by the server.

Creating OPC Toolbox Object Vectors

OPC Toolbox software supports the use of object vectors. An object vector is a single variable in the MATLAB workspace containing a reference to more than one object. For example, all the groups added to an are stored in the client’s

dagroup object vector that represents all groups in that client. Similarly,

Group property. The Group property contains a

opcda client object

3-9

3 Using OPC Toolbox™ Objects

a dagroup object has an I tem property that contains a reference to every

daitem object created in the group.

You can construct vectors using any of the standard concatenation techniques available in MATLAB. However, OPC Toolbox software imposes some limitations on the construction of object vectors:

• Objects must be the same class. For example, you can concatenate two

dagroup objects, but you cannot concatenate a dagroup object with a daitem object.

• Group and item objects must have the same parent.

• One of the dimensions of the resulting array must be scalar. You can create

a column vector (m-by-1 objects) or a row vector (1-by-n objects), but not an m-by-n matrix.

• OPC Toolbox software does not fill in missing elements in a vector. Instead,

an error is generated. For example, you cannot assign a scalar object at the 4th index to a scalar object.

3-10

The following sections discuss how to create and use toolbox object vectors:

• “Constructing Object Vectors” on page 3-10 describes how to create object

vectors.

• “Displaying a Summary of Object Vectors” on page 3-11 describes ho w

object vectors are displayed at the command line.

• “Using Object Vectors” on page 3-12 describes how you can use object

vectors with O PC Toolbox software.

Constructing Object Vectors

You can construct an object vector using any of the following techniques:

• Using concatenation of lists of individual object variables

• Using indexed assignment

• Using object properties to retrieve object vectors

Creating OPC Toolbox™ Objects

Creating object vectors u sing concatenation. To construct an OPC Toolbox object vector using concatenation, you use the normal MATLAB syntax for concatenation. Create a list of all objects you want to create, and surround that list with square brackets (

[]). Separate each element of the

object vector by either a comma (,) to create a row vector, or a semicolon (;) to create a column vector.

The following example creates three fictitious

opcda client objects, and

concatenates them into a row vector.

da1 = opcda('Host1','Dummy.Server.1'); da2 = opcda('Host2','Dummy.Server.2'); da3 = opcda('Host3','Dummy.Server.3'); dav = [da1, da2, da3];

Creating object vectors using indexed assignment. Indexed assignment refers to creating vectors by assigning elements to specific indices in the vector. The following example constructs the same three-element

opcda client

object vector as in the previous example, using indexed assignment.

dav(1) = opcda('Host1','Dummy.Server.1'); dav(2) = opcda('Host2','Dummy.Server.2'); dav(3) = opcda('Host3','Dummy.Server.3');

Creating object vector using object properties. You may obtain an object vector if you assign the

Group property of a opcda client object, or the Item

property of a dagroup object, to a variable. If the client has more than one group, or the group has m ore than one item, the resulting property is an object vector.

For information on obtaining object properties, see “Viewing the Value of a Particular Property” on page 3-19.

Displaying a Summary of Object Vectors

To view a summary of an object vector, type the name of the object vector at the command prompt. For example, this is the summary of the client vector

dav.

dav =

3-11

3 Using OPC Toolbox™ Objects

The summary information for each OPC Toolbox object class is different. However, the basic display is similar.

Using Object Vectors

You use object vectors just as you would a normal object variable. The function you c al l with the object vector simply gets applied to all objects in the vector. For example, passing the client vector connects each object in the vector to its OPC server.

Note Some OPC Toolbox functions do not accept object vectors as arguments. If you attempt to use an object vector with a function that does not accept object vectors, an error will be generated. Consult the relevant function reference page for information on whether a function supports object vectors.

OPC Data Access Object Array:

Index: Status: Name: 1 disconnected Host1/Dummy.Server.1 2 disconnected Host2/Dummy.Server.2 3 disconnected Host3/Dummy.Server.3

dav to the connect function

3-12

If you need to extract elements of an object vector, use standard MATLAB indexing notation. For example, the following example extracts the second element from the client vector

dax = dav(2);

dav.

Working with Public Groups

The OPC Data Access Specification provides a mechanism for sharing group configuration amongst many clients. Normally, a client has private access to a group; no other client connected to the same server can see that group, and the items configured in that group. However, a client can define a group as public, allowing other clients connected tothesameservertogainaccessto that group.

Creating OPC Toolbox™ Objects

Note The OPC Data Access Specification defines the support for public groups as optional. Consequently, some OPC servers will not support public groups.

A public group differs from a private group in the following ways:

• Once a group is defined as public, you cannot add items to that group, nor

remove items from the group. This restriction ensures that every client using that public group has access to the same items, and does not need to worry about items being a dded or removed from that group. You should ensure that a group’s items are correct before making that group public.

• Each client that accesses the public group is able to set its own group

properties, such as the

Subscription properties. For example, one client can define an UpdateRate of 10 seconds for a public group, while another client specifies

the

UpdateRate as 2 seconds.

UpdateRate, DeadbandPercent, Active,and

• Each public group defined on a server must have a unique name. If you

attempt to create a public group with a name that is the same as a public group on the server, an error is generated.

• A single client cannot have a public group and a private group with the

same name. For example, you cannot connect to a public group named

'LogGroup' and then create a private group called 'LogGroup'.

Using OPC Toolbox software, you can define and publish your own public groups or connect to existing public groups. You an also request that public groups be removed from an OPC server. The following sections illustrate how you can work with public groups using OPC Toolbox software:

• “Defining a New Public Group” on p age 3-14 describes how you can create

new public groups.

• “Connecting to an Existing Public Group” on page 3-14 describes how you

can u tilise a public group that is already defined on the server.

• “Removing Public Groups from the Server” on page 3-16 describes how you

can remove public groups from an OPC server.

3-13

3 Using OPC Toolbox™ Objects

Defining a New Public Group

You define a new public group b y creating a private group in the n orm a l way (described in “Creating Data Access Group Objects” on page 3-2) and then converting that private group into a public group.

You use the group. The only argument to the

makepublic function to convert a private group into a public

makepublic function is the group object that

you want to convert to a public group.

The following example creates a private group, with specific items in that group. The group is then converted into a public group.

da = opcda('localhost', 'My.Server.1'); grp = addgroup(da, 'PublicGrpExample'); itms = additem(grp, {'Item.ID.1', 'Item.ID.2'}); makepublic(grp);

You can check the group type using the GroupType property.

get(grp, 'GroupType')

ans =

public

Connecting to an Existing Public Group

In addition to creating new public groups, you can also create a connection to an existing public group on the server. To obtain a list of available public groups on a server, you use the object that is connected to the s erver as the argument. The returned structure includes a field called

'PublicGroups', containing a cell array of public

groups defined on that server. If the should check the

'SupportedInterfaces' field to ensure that the server

supports public groups. A server that supports public groups will implement the

IOPCServerPublicGroups interface.

opcserverinfo function, passing the client

'PublicGroups' field is empty, then you

3-14

Once you have a list of available public groups, you can create a connection to that group using the

addgroup function, passing it the client that is connected

to the server containing the public group, the name of the public group, and the

'public' group type specifier.

Creating OPC Toolbox™ Objects

Note You cannot create a connection to an existing public group if your client object is disconnected from the server.

Thefollowingexampleconnectstoapublicgroupnamed'PublicTrends' on the server with program ID

da = opcda('localhost', 'My.Server.1'); connect(da); pubGrp = addgroup(da, 'PublicTrends', 'public');

'My.Server.1'.

When you connect to a public group, the items in that group are automatically created for you.

itm = get(pubGrp, 'Items');

itm =

OPC Item Object Array:

Index: DataType: Act ive: ItemID: 1 double on item.id.1 2 uint16 on item.id.2 3 double on item.id.3

You cannot add items to or remove items from a p ublic group. H o we ver, you can still modify the update rate of the group, the dead band percent, and the active and subscription status of the group, and you can use the group to read, write, or log data as you would for a private group.

When you have finished using a public group, you can use the

delete function

to remove that group from your client object. Deleting the group from the client does not remove the public group from the server; other clients might require that group after you have finished with it. Instead, deleting the group from the client indicates to the server that you are no longer interested in the group.

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3 Using OPC Toolbox™ Objects

Removing Public Groups from the Server

You can request that a public group be removed from a server using the

removepublicgroup function, passing the client object that is connected to

theserverandthenameofthepublicgrouptoremove.

Caution The OPC Data Access Specification does not provide any security mechanism for removing public groups; any client can request that a public group be removed. You should use this function with extreme caution!

If any clients are currently connected to that group, the server will issue a warning stating that the group will be removed when all clients have finished using the group.

3-16

Configuring OPC Toolbox™ Object Properties

Configuring OPC Toolbox Object Properties

In this section...

“Purpose of Object Properties” on page 3-17

“Viewing the Values of Object Properties” on page 3-18

“Viewing the Value of a Particular Property” on page 3-19

“Getting Information About O bject Properties” on page 3-19

“Setting the Value of an Object Property” on page 3-20

“Viewing a List of All Settable Object Properties” on page 3-21

Purpose of Object Properties

All OPC Toolbox objects support properties that enable you to control characteristics of the object:

• The

For a ll three toolbox objects, y ou can use the same toolbox functions to

• View a list of all the properties supported by the object, with their current

• View the value of a particular property

opcda client object properties control aspects of the connection to the

OPC server, and event information obtained from the server. For example, you can use the to respond to a request from the client.

dagroup object properties control aspects of the collection of items

contained within that group, including all logging properties. For example, the

UpdateRate property defines how often the items in the group must be

checked for value changes, as well as t he rate at which data will be sent from the server during a logging session.

daitem object properties control aspects of a single server item. For

example, you use the server must use to send values of that s erver item to the OPC Toolbox software.

values

Timeout property to define how long to w ait for the server

DataType property to define the data type that the

3-17

3 Using OPC Toolbox™ Objects

• Get information about a property

• Set the value of a property

Viewing the Values of Object Properties

To view all the properties of an OPC Toolbox object, with their current values, use the

get function.

If you do not specify a return value, the

get function displays the object

properties in categories that group similar properties together. You use the display form of the

get function to view the value of all properties for the

toolbox object.

This example uses the the OPC

dagroup object grp.

get(grp)

General Settings:

DeadbandPercent = 0 GroupType = private Item = [] Name = group1 Parent = [1x1 opcda] Tag = TimeBias = 0 Type = dagroup UpdateRate = 0.5000 UserData = []

Callback Function Settings:

CancelAsyncFcn = @opccallback DataChangeFcn = [] ReadAsyncFcn = @opccallback RecordsAcquiredFcn = [] RecordsAcquiredFcnCount = 20 StartFcn = [] StopFcn = [] WriteAsyncFcn = @opccallback

get function to display a list of all the properties of

3-18

Configuring OPC Toolbox™ Object Properties

Subscription and Logging Settings:

Active = on LogFileName = opcdatalog.olf Logging = off LoggingMode = memory LogToDiskMode = index RecordsAcquired = 0 RecordsAvailable = 0 RecordsToAcquire = 120 Subscription = on

Viewing the Value of a Particular Property

To view the value of a particular property of an OPC Toolbox object, use the

get function, specifying the name of the property as an argument. You can

also access the value of the property as you would a field in a MATLAB structure.

This example uses the

get function to retrieve the value of the Subscription

property for the dagroup object.

get(grp,'Subscription')

ans =

This example illustrates how to access the same property by referencing the object as if it were a MATLAB structure.

grp.Subscription

ans =

Getting Information About Object Properties

To get information about a particular property, you can view the reference page for the property in Chapter 9, “Functions — Alphabetical List”. You can also get information about a particular property at the command line by using the

propinfo or opch elp functions.

3-19

3 Using OPC Toolbox™ Objects

The propin fo function returns a structure that contains information about the property, such as its data type, default value, and a list of all possible values if the property supports such a list. This example uses get information about the

propinfo(grp,'LoggingMode')

ans =

The opchelp function returns reference information about the property with a complete description. This example uses the

opchelp(grp,'LoggingMode')

propinfo to

LoggingMode property.

Type: 'string'

Constraint: 'enum'

ConstraintValue: {'memory' 'disk' 'disk&memory'}

DefaultValue: 'memory'

ReadOnly: 'whileLogging'

opchelp to get information about

LoggingMode property.

3-20

Setting the Value of an Object Property

To set the value of a particular property of an OPC Toolbox object, use the set function, specifying the name of the property as an argument. You can also assign the value to the property as you would a field in a MATLAB structure.

Note Because some properties are read-only, only a subset of the toolbox object properties can be set. Use the property reference pages or the function to determine if a property is read-only.

This example uses the set function to set the value of the LoggingMode property.

set(grp,'LoggingMode','disk&me

mory')

To verify the new value of the property, use the get function.

get(grp,'LoggingMode')

propinfo

Configuring OPC Toolbox™ Object Properties

ans =

disk&memory

This example sets the value of a property by assigning the value to the object as if it were a MATLAB structure.

grp.LoggingMode = 'disk'; grp.LoggingMode

ans =

disk

Viewing a List of All Settable Object Properties

To view a list of all the properties of a toolbox object that can be set, use the

set function.

set(grp)

General Settings: DeadbandPercent Name Tag TimeBias UpdateRate UserData

Callback Function Settings:

CancelAsyncFcn: string -or- function handle -or- cell array DataChangeFcn: string -or- function handle -or- cell array ReadAsyncFcn: string -or- function h andle -or- cell array RecordsAcquiredFcn: string -or- function handle -or- cell array RecordsAcquiredFcnCount StartFcn: string -or- function handle -or- cell array StopFcn: string -or- func tion handle -or- cell array WriteAsyncFcn: string -or- function handle -or- cell array

Subscription and Logging Settings:

Active: [ {on} | off ] LogFileName

3-21

3 Using OPC Toolbox™ Objects

When using the set function to display a list of settable properties, all properties that have a predefined set of acceptable values list those values after the property. The default value is enclosed in curly braces ( example, from the display shown above, you can set the property for a dagroup object to 'on' or 'off', with the default value being

'on'.YoucansettheLogFileName property to any value.

Special Read-Only Modes

Some OPC Toolbox object properties change their read-only status, depending on the state of an object (defined by another property of that object, or the parent of that object). The toolbox uses two special read-only modes:

•

'whileConnected': These properties cannot be changed while the client

is connected to the OPC server. For example, the client’s read-only while connected.

LoggingMode: [ {memory} | disk | disk&memory ] LogToDiskMode: [ {index} | append | overwrite ] RecordsToAcquire Subscription: [ {on} | off ]

{}). For

Subscription

Host property is

3-22

•

'whileLogging': These properties cann ot b e changed while the dagroup

object is logging. For example, the Loggi ngMode property is read-only while logging. For more information on logging, see “Logging OPC Server Data” on p age 4-17.

•

'whilePublic': These properties cannot be changed because the group is a

public group. For more information on public groups, see “Working with Public Groups” on page 3-12.

Note Properties that modify their read-only state are always displayed when using

set to display settable properties, even when they cannot be

changed because of the state of the object.

To de te rmine if a property has a modifiable read-only state, use the propinfo function.

Deleting Objects

When you finish using your OPC Toolbox objects, use the dele te function to remove them from memory. After deleting them , clear the variables that reference the objects from the MATLAB workspace by using the function.

Note When y ou delete an opcda client object, all the group and item o bjects associated with the delete a object are deleted.

To illustrate the deletion process, this example creates several opcda client objects and then deletes them.

Step 1: Create several clients

Deleting Objects

clear

opcda client object are also deleted. Similarly, when you

dagroup object, all daitem objects associated with that dagroup

This example creates several

opcda client objects using fictitious host and

server ID properties.

da1 = opcda('Host1','Dummy.Server.1'); da2 = opcda('Host2','Dummy.Server.2'); da3 = opcda('Host3','Dummy.Server.3');

Step 2: Delete clients

Always remove toolbox objects from memory, and the variables that reference them, when you no longer need them.

You can delete toolbox objects using the

delete(da1) delete(da2) delete(da3)

delete function.

Note that the variables associated with the objects remain in the workspace.

whos

3-23

3 Using OPC Toolbox™ Objects

These variables are not valid OPC Toolbox objects.

isvalid(da1)

ans =

To rem ove these variables from the workspace, use the clear command.

Note You can delete toolbox object vectors using the delete function. You can also delete individual elements of a toolbox object vector.

Name Size Bytes Class

da1 1x1 636 opcda object da2 1x1 636 opcda object da3 1x1 636 opcda object

3-24

Saving and Loading Objects

Using the save command , you can save an OPC Toolbox object to a MAT-file, just as you would any workspace variable. This example saves the object grp to the MAT-file myopc.mat.

save myopc grp

When y ou save a toolbox object, all the toolbox objects in that object hierarchy are also saved. For example, if you save a groups associated with that client and all items created in those groups are saved along with the save will be created in the MATLAB workspace. Other objects will be created with no reference to them in the workspace. To obtain a reference to an existing OPC Toolbox object, use the

To load a toolbox object that was saved to a MAT-file into the MATLAB workspace, use the

myopc.mat,use

dagroup object. However, only those objects you elect to

load command. For example, to load grp from MAT-file

Saving and Loading Objects

dagroup

dagroup object, the client, all

opcfind function.

load myopc

Note The values of read-only properties are not saved. When you load a toolbox object into the MATLAB workspace, read-only properties revert back to their default values. To determine if a property is read-only, use the

propinfo function or see Chapter 11, “Properties — Alphabetical List”.

3-25

3 Using OPC Toolbox™ Objects

3-26

Reading, Writing, and Logging OPC Data

The core of any OPC To olbox software application is the exchange of data between the MATLAB workspace and one or more OPC servers. You create and configure toolbox objects to support the reading, writing, and data logging functions that you require for your application.

Using OPC T oolbo x software you can exchange data with an OPC server in a number of ways. You can read and write data from the MATLAB command line or other MATLAB functions. You can configure toolbox objects to automatically run MATL AB code when the server notifies the objects that data has changed on the server. You can also log changes in OPC server data to a disk file or to memory, for further analysis.

This chapter provides information on how to exchange data with an OPC server.

• “Reading and Writing Data” on page 4-2

• “Data Change Events and Subscription” on page 4-12

• “Logging OPC Server Data” on page 4-17

4 Reading, Writing, and Logging OPC Data

Reading and Writing Data

In this section...

“Introduction” on page 4-2

“Reading Data from an Item” on page 4-2

“Writing Data to an Item” on page 4-6

“Reading and Writing Multiple Values” on page 4-8

Introduction

Using OPC Toolbox software, you can exchange data with the OPC server using individual items, or using the on multiple items. T he reading and writing operation can be performed synchronously, so that your M ATLAB session will wait for the operation to complete, or asynchronously, allowing your MATLAB session to continue processing while the operation takes place in the background.

dagroup object to perform the operation

4-2

Reading Data from an Item

You can read data from any item that is associated with a connected client. When you perform the read operation on an item, the server will return information about the server item a ssociated with that item ID. The read operation can be performed synchronously or asynchronously:

• “Using Synchronous Read Operations” on page 4-2 describes how to

perform synchronous read operations. Synchronous read operations can request data from the server’s cache, or directly from the device.

• “Using Asynchronous Read Operations” on page 4-5 describes how to

perform asynchronous read operations.

Using Synchronous Read Operations

A synchronous read operation means that MATLAB will wait for the server to return data from a read request before continuing processing. The data returned by the server can come from the server’s cache, or you can request that the server read values from the device that the server item refers to.

Mathworks OPC TOOLBOX 2 user guide

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Product Overview

About O PC Toolbox Software

About OPC

Understanding OPC Data Access Servers

OPC Server Name Spaces

Understanding the OPC Toolbox Object Hierarchy

How OPC Toolbox Objects Relate to OPC Servers

System Requirements

Getting Command-Line Function Help

Preparing to Use OPC Toolbox Software

Introduction

Installing the OPC Foundation Core Components

Configuring DCOM

Configuring DCOM to Use Named User Security

Configuring DCOM to Use No Security

Installing the Matrikon OPC Simulation Server

Exploring Available OPC Servers

Prerequisites

Determining Server IDs for a Host

Server Information Returned by opcserverinfo

Connecting to OPC Servers

Overview

Creating a Client Object

Viewing a Summary of a Client Object

Connecting a Client to the Server

Browsing the OPC Server Name Space

Getting the Server Name Space

Getting Information about a Specific Server Item

Troubleshooting

Introduction

Unable to Find an OPC Server

Quick Start: Using the O PC Tool GUI

Example: Basic OPC Toolbox Acquisition Procedure

Overview

Step 1: Open the OPC Tool GUI

Command-Line Equivalent

Step 2: Locate Your OPC Server

Command-Line Equivalent

Step 3: Create an OPC Data Access C lient Object

Alternative Methods for Creating Clients

Command-Line Equivalent

Command-Line Equivalent

Command-Line Equivalent

Step 6: Browse the Server N ame Space

Command-Line Equivalent

Step 7: Add OPC Data Access Items to the Group

Reading a Value from the Server

Adding More Items to the Group

Command-Line Equivalent

Step 8: View All Item Values

Command-Line Equivalent

Step 9: Configure Group Properties for Logging

Command-Line Equivalent

Step 10: Log OPC Server Data

Command-Line Equivalent

Step 11: Plot the Data

Step 12: Clean Up

Command-Line Equivalent

Using OPC Toolbox Objects

Creating OPC Toolbox Objects

Overview

Creating Data Access Group Objects

Specifying a Group Name

Viewing a Summary of a Group Object

Using a Group Object

Creating Data Access Item Objects

Specifying a Local Data Type for the Item

Specifying the Active Status of an Item Object

Viewing a Summary of the Item Object

Using an Item Object

Building an Object Hierarchy with a Disconnected Client

Creating OPC Toolbox Object Vectors

Constructing Object Vectors

Displaying a Summary of Object Vectors

Using Object Vectors