URT Concepts Guide

7/29/2019 URT Concepts Guide

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Honeywell Process Solutions

Unified Real Time

Concepts Guide

UR90-200A

R320

11/08

Release 320


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ii Unified Real Time Concepts Guide R32011/08

Notices and Trademarks

Copyright 2008 by Honeywell International Inc.Release 320 November, 2008

While this information is presented in good faith and believed to be accurate, Honeywell disclaimsthe implied warranties of merchantability and fitness for a particular purpose and makes noexpress warranties except as may be stated in its written agreement with and for its customers.

In no event is Honeywell liable to anyone for any indirect, special or consequential damages. Theinformation and specifications in this document are subject to change without notice.

Honeywell is registered trademark of Honeywell International Inc.

Other brand or product names are trademarks of their respective owners.

Honeywell Industry Solutions

2500 West Union Hills Drive

Phoenix, AZ 85027

1-800 343-0228


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R320 Unified Real Time Concepts Guide iii11/08

About This Publication

In This Publication

Purpose

This publication gives an overview of Unified Real Time (URT) infrastructure and

explains the concepts related to URT.

Who should use this publicationIf you are a control engineer involved in configuring control or other on-processapplications hosted by URT, or if you are authoring new functionality for use within a

URT environment and looking for the background information, this publication is for

you.

Prerequisites

You should have some familiarity with process control or other on-process applications.

References

The following list identifies other publications in this book-set that may be sources of reference

for material discussed in this publication.

If you Refer Document ID

are looking for instructions onimplementation

Profit Suite ImplementationTechnical Reference Guide

RM20-520

are a general user of URTlooking for the procedural orhow-to information

URT Users Guide UR20-200A

are looking for information onuse of URT SoftwareDevelopment Kit

URT SDK Users Guide UD20-200A


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About This Publicati onContacts

iv Unified Real Time Concepts Guide R32011/08

Contacts

World Wide Web

The following Honeywell web sites may be of interest to URT customers.

Honeywell Organization WWW Address (URL)

Corporate http://www.honeywell.com

Process Solutions http://www.honeywell.com/ps

Telephone

Contact us by telephone at the numbers listed below.

Organization Phone Number

United Statesand Canada

Honeywell International Inc.Process Solutions

1-800-343-0228 Sales1-800-525-7439 Service1-800-822-7673 Technical

Support

Asia Pacific Honeywell Asia Pacific Inc.Hong Kong

(852) 23 31 9133

Europe Honeywell PACE

Brussels, Belgium

[32-2] 728-2711

Latin America Honeywell International Inc.Sunrise, Florida U.S.A.

(954) 845-2600
http://www.honeywell.com/http://www.honeywell.com/pshttp://www.honeywell.com/pshttp://www.honeywell.com/


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About This Publ icationWriting Conventions

R320 Unified Real Time Concepts Guide v11/08

Writing Conventions

Formatting Conventions

Following formatting conventions are used in this publication.

Convention Explanation

Words in boldtype

Field names including buttons in the display, or important phrases.

Arrow Windows pull down menus and their options are separated by.

For example, click FileNew to open the NewPlatform dialog.

Courierfont

Information that you type, parts of the code quoted for explanationsor as examples.

UPPERCASE Acronyms

UPPERCASEwithin anglebrackets

Command keys

For example, press .

Zero as a value. When there is a chance for confusion with the letterO, zero is denoted as .

In all other cases, zero as a numerical placeholder is denoted as 0.

For example, 1.0, 10, 101, CV1, parameter P.

Abbreviations and Terminology

Following alphabetical list gives the technical definitions of terms specific to URT

Term Meaning

Alarms andEvents

OPC terminology. Equivalent URT term is message. See message.

Check PointFile

File that contains a snapshot of the full configuration data of aplatform with extension .urt.

Command Function blocks and other tree members respond to commands. Forexample, to get a function block to execute, a command must besent to it.

Data Item URT representation of numerical or string data. A data item could be


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About This Publicati onWriting Conventions

vi Unified Real Time Concepts Guide R32011/08

Term Meaning

a scalar or array item. Many properties, such as the quality of thedata, are associated with each data item.

Element Also referred to as a Tree Member. See Tree Member.

EmbeddedPHD

Lightweight version of Uniformance PHD that doesnt require Oracle,used for real-time history.

FunctionBlock

Function blocks provide automation and control functionality.Function blocks typically interact with data items to manipulate data.The data items can be connected to external systems via the OPCclient.

Interval The time between function block executions.

HistoryCollection

Configuring a historian to historize URT data items.

HistoryRetrieval

Retrieving history data from a historian.

Issue (amessage)

After processing a message, the message manager decideswhether it should be issued. The message manager may not issuethe message if it has already been issued.

Leaf node The outermost node(s) in a URT tree.

Limit The maximum or minimum allowed value.

Log Viewer A tool used to view URT events in the Windows Event Log.

Message A textual message that informs the user of a condition. In the URTcontext, there are three types of message: Raise, Simple and Track.

All messages are sent to the URT log file. The URT OPC Serveralso is informed of URT messages.

Messagesource file

File that contains message text and other message properties formessages that will potentially be raised.

Message logfile

File that contains messages that the message manager has issued.

OPC Ole for Process Control industry standard.

OPC Client The URT OPC Client can be configured to connect to any OPCserver to get or put data.

OPC server The URT OPC server runs as a separate executable. Any OPC


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About This Publ icationWriting Conventions

R320 Unified Real Time Concepts Guide vii11/08

Term Meaning

client can connect to URTs OPC server and request URT data.

OPC A&Eserver

The URT OPC server also implements an Alarms and Events (A&E)server that informs its clients of URT Alarms and Events.

OPC HDAserver

Most historians implement an OPC HDA (history data access) serverwhich serves up history data.

Platform A process that contains the function blocks and data items that carryout application functionality and executes the configured applicationsin real-time

Process To a process control engineer, process usually refers to amanufacturing process or plant. To a programmer, a process is anexecutable program.

To avoid confusion, the term Windows process is used to refer toan executable program.

Pull (data) To read data from an external (or sometimes internal) source.

Push (data) To write data to an external (or sometimes internal) source.

Quality A property typically associated with data. Indicates the status of thedata for example suspect.

Raise (amessage)

Function blocks raise messages via the message manager. Themessage manager decides whether it should be issued.

Range A contiguous set of numerical values from a low value to high value.

Save aplatform

Platform configuration is written to an .URT file.

Schedulingblock

A URT tree member that can be configured to schedule functionblocks to run at specified intervals.

Tree Also known as platform. The URT platform configuration is a Treestructure.

Tree Member An item configured on the URT platform. Tree members can be dataitems, function blocks, scheduling blocks, etc.

WindowsProcess

A Microsoft computer process.


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About This Publicati onWriting Conventions

Symbol Definitions

Following symbols are used in this publication to denote certain conditions.

Symbol Definition

ATTENTION: Identifies information that requires specialconsideration.

TIP: Identifies advice or hints for the user, often in terms of

performing a task.

REFERENCE -EXTERNAL: Identifies an additional source ofinformation outside of the book-set.

REFERENCE - INTERNAL: Identifies an additional source ofinformation within the book-set.

CAUTION Indicates a situation which, if not avoided, may result in equipmentor work (data) on the system being damaged or lost, or may result inthe inability to properly operate the process.

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R320 Unified Real Time Concepts Guide ix11/08

Contents

1. OVERVIEW OF URT ....................................................................13

1.1 About URT......................................................................................................13Introduction to URT ..............................................................................................................13Features...............................................................................................................................14

1.2 Building Blocks .............................................................................................15Platforms..............................................................................................................................15Function blocks ....................................................................................................................15Scheduling module...............................................................................................................16Data items............................................................................................................................16Data wrappers......................................................................................................................17

1.3 Subsystems ...................................................................................................17URT Explorer .......................................................................................................................17URT Messaging System.......................................................................................................17Process interface components.............................................................................................18History Collection and Retrieval ...........................................................................................18Checkpoint Function Block...................................................................................................18URT Service.........................................................................................................................19

2. PLATFORMS ...............................................................................21

2.1 Introduction to Platforms ............................................................................. 21What is a URT platform........................................................................................................21How many applications per platform ....................................................................................21How many platforms per computer ......................................................................................21

2.2 Structure ........................................................................................................ 22

2.3 Operation ....................................................................................................... 23

3. DATA ITEMS................................................................................25

3.1 Int roduct ion to Data Items............................................................................ 25

3.2 Types of Data Items ...................................................................................... 26

3.3 At tr ibutes of Data Items................................................................................26

4. FUNCTION BLOCKS ...................................................................29


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Contents

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4.1 Introduction to Function Blocks ..................................................................29

4.2 Organizing Funct ion Blocks .........................................................................29

4.3 Organizing Data .............................................................................................30Introduction to organizing data ............................................................................................ 30Function-centric organizatin ................................................................................................ 30Data-centric organization .................................................................................................... 32

5. COMMANDS................................................................................ 35

5.1 What is a command .......................................................................................35

5.2 How does a command work .........................................................................35

6. EXECUTION ................................................................................ 37

6.1 Execut ion Scheduling ...................................................................................37

6.2 Execut ion Cycle .............................................................................................37Overview of execution cycle................................................................................................ 37PreExecute.......................................................................................................................... 38Execute ............................................................................................................................... 38PostExecute ........................................................................................................................ 38

6.3 Execut ion Thread...........................................................................................39

7. MESSAGING ............................................................................... 41

7.1 URT Messaging System ................................................................................41

7.2 Components of Messaging System .............................................................43Message source file ............................................................................................................ 43Message component ........................................................................................................... 43Message manager component............................................................................................ 44Receiving Notification of an Acknowledgment..................................................................... 47Support for raising messages.............................................................................................. 47Interface with URT OPC Alarms and Events Server ........................................................... 47

8. PROCESS INTERFACE .............................................................. 49

8.1 Introduction to Process Interface in URT....................................................49

8.2 About OPC......................................................................................................50

8.3 URT OPC Server ............................................................................................51

8.4 URT OPC Client fo r Data Access .................................................................51


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Contents

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9. HISTORY COLLECTION AND RETRIEVAL................................53

9.1 Introduction to History Collection and Retrieval in URT ........................53

9.2 URT History Collect ion .................................................................................54

9.3 URT History Retr ieval ...................................................................................54

10. SECURITY....................................................................................55


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1. Overview of URT

1.1 About URT

Introduction to URT

What is URT?

Unified Real Time (URT) is an infrastructure for implementing real-time, advanced

process control applications.

Where can you use URT?

In Honeywells layered approach to process control, URT based applications fit in theuppermost layer. Level-one and level-two process control that is critical for reliable, safe,

and effective operation generally resides in a process system rather than in a URT

environment. URT, then, provides the infrastructure to implement level-three process

control applications. These applicationsoften large and complexcater to increasingprofitability of the operation, additional automation, or other value-added services such

as online optimization, early event detection, and so on.

URT includes the service of OPC client and server for communicating to the processsystem and devices. If a client requires services such as access to process data or real-

time execution, the client application can use URT as a slave to achieve this. Thus, you

can use URT as a complete infrastructure or as a set of tools, depending on your

applications needs.

What are the prerequisites?

By itself URT does not provide connection to process devices. Therefore, it requires the

services of one or more process systems through which it can input and output processdata. To use URT effectively, level-one and level-two control layers should already be in

place.

URT requires Windows 2000 or later as the operating system.


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1. Overview of URT1.1. About URT

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Features

The strength of URT lies in its generality, flexibility, modularity, and scalability.

Generality:

URTs design is not restricted to any specific application.

It supports all the commonly used data types and structures.

It includes the services of an OPC client and an OPC server to communicate with

any third-party control system.

It uses Unicode character encoding throughout, making it easy to represent

multilingual text, particularly in the operator interfaces.

URT is thus best suitable for unifying different on-process applications developed atdifferent times and for different situations.

Flexibility:

Using URT infrastructure, you can develop a variety of applications that have

different execution scheduling, thread use, and organization.

Depending on the applications needs, you can use it either as a complete

infrastructure or as a set of tools.

Modularity:

Owing to the organization in different function blocks, you can reuse the functionblocks providing common functionalities and minimize redundant development and

maintenance.

You can build complex applications in modular steps.

Scalability:

The applications developed using URT infrastructure can cover a wide range of

application sizes, complexity, and mixes.


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1. Overview of URT1.2. Building Blocks

1.2 Building Blocks

Platforms

A URT platform provides the framework on which applications are configured and

executed.

A platform


Holds the function blocks and data items that carry out application functionality, and

Executes the configured applications in real-time.

Any number of applications can reside on a single platform and any number of platformscan be executed on a single computer.

REFERENCE - INTERNAL

For more details, see "Platforms".

Function blocks

Function blocks are in-process components that you can configure to provide desired

automation and control functionality.

Function blocks can range from small functions such as a digital filter or a PID loop to

very large functions such as a multivariable controller.

URT provides function blocks that are generally needed for platform operations such asscheduling and execution of other function blocks. It also provides an OPC Client

function block for interfacing with the process that is outside of URT.

You can develop the function blocks in programming languages that are compatible withCOM or .NET, such as C++, C# and VB.NET.


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1. Overview of URT1.2. Building Blocks

The URT Software Development Kit provides the base class, boilerplate code, and a

wizard for authoring new function blocks.


For more background information on function blocks, see "Function Blocks".

Scheduling module

A scheduling module controls the execution of all components under it. It includes a

scheduling block and the components under the scheduling block.


For more information on scheduling and execution, see "Execution".

Data items

Data items are in-process components that make data visible outside the function blocks

that use the data.

A data item is created to hold a piece of data for any of the following reasons.

The data is to be pulled from or pushed to another data item during execution.

The data will be accessed by clients such as configurators, operating displays, or the

OPC server.

The data must be persistent across restarts.Data items can be created either by a function block that uses the data or by a

configurator, and can be created statically or dynamically.

A data item can be a scalar value, a container (array, list, stack, queue, and so on) or astructure. Containers and structures can be nested to any level. Multi-dimensional arrays

to any level can be formed by creating arrays of arrays (to any level) of elements.

URT provides all the usual data types.

In addition to the value or values that it exposes, a data item has attributes such as aname, description, engineering units, an optional connection to another data item,

optional input and output buffer, quality, and reasonable-value range.


For more information on the properties of data items and the reasoningbehind configuring the properties see Data Items.



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1. Overview of URT1.3. Subsystems


Data wrappers

If you are using C++ to implement function blocks, you will be using data wrappers.

Data wrappers are C++ classes that wrap data item components to make the data itemseasy to use.

In VB and C# data items are used directly as these languages hide the complexities of

component usage.

1.3 Subsystems

URT Explorer

URT Explorer gives a visual depiction of a URT platform, its components and structure.You can use it

To create, configure, monitor, and operate URT platforms

To view messages

To add, delete, reorganize and configure data items and function blocks

As a tool for developing and testing new functionality and applications

To visualize the structure and operation of a URT platform

URT Explorer can be used to configure any application instance. However, application

authors may consider providing a custom user interface for configuration of anapplication instance on the URT infrastructure. Such a custom interface can provide

defaults and guidance to your users, making the configuration easier and user friendly.

Though URT Explorer can be used with any application, it is not intended to be used by

operators. For operators, you should provide interfaces tailored to your application.Operator interfaces can be implemented within the HMIWeb framework supported by

URT (not supported in Release 220), or using an OPC client to communicate with URT.

URT Messaging System

The URT messaging system is used to issue messages and alarms to the user.

You can view, sort and filter current messages and alarms in URT Explorer. In addition,all messages and alarms are logged into the Windows Event Log. This log can also be

viewed via URT Explorer.

URT messages and alarms integrate seamlessly with Honeywells Experion Alarms andEvents system via the URT OPC Alarms and Events server.


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The message text and other message parameters, such as message priority, are stored in

XML formatted message source files. Because of this, URT messages can be localized.


For background information on the URT messaging mechanism, see"Messaging".

Process interface components

As URT is mainly designed for developing process control related applications, it

supports the OPC standards. URT includes:

The OPC client capability to communicate with process systems. It provides afunction block OPC Client for Connections to exchange data with an OPC

Server.

An OPC server (both Data Access and Alarms and Events) that external clients canuse to access URT platforms data. The OPC server provides an industry-standard

interface for clients that have no knowledge of URT components.

To communicate with a process system that does not support an OPC (DA) server, you

may provide custom client capability.

REFERENCE INTERNAL

For more background information on OPC communication in URT, seeProcess".

History Collection and Retrieval

Many applications like lab update have short term history needs; in order to historize a

value and to also retrieve history values. URT addresses this with the following

components:

The capability to automatically configure embedded PHD to collect history fromURT data items. It provides a function block Collect History to do this.

The OPC client capability to retrieve history. It provides a function block OPC

Client for History to retrieve data from an OPC (HDA) Server.

Checkpoint Function Block

An automatic checkpoint function block CheckPoint is provided with URT. Itis capable of automatically checkpointing a URT platform, or a branch of a platform.The checkpoint frequency is based on the scheduler interval it is running under.



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URT Service

Every time you start your computer, URT Platform Launcher launches all the URT

platforms available in the platform directory that are configured to start automatically.You can configure a platform to either start automatically or manually. URT Service also

monitors the status of platforms.


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2. Platforms

2.1 Introduction to Platforms

What is a URT platform

A URT platform is a collection of data items, function blocks and schedulers that youconfigure to monitor, automate, and control all or part of a plant.

Each URT platform is a COM component that runs in its own Windows process. Data

items and function blocks that are configured on the URT platform are in-process

components to insure efficient processing.

How many applications per platform

In the context of URT, an application is a closely related set of functionalities, typicallyorganized and packaged so that instances of the application can be easily configured on a

platform. An application can be as small as a single-loop controller or as large as a

multivariable controller or on-line optimization.

URT does not impose restrictions on the number of applications that you may configureon a single platform. The host computers processing and memory resources will limit

the number of applications that reside on the platforms on a given computer.

How many platforms per computer

You can execute any number of platforms on a single computer. Data connections are

configured much the same way whether they are within a platform or between platforms,either local or remote, so you have considerable flexibility in deciding how to distribute

applications.

You may decide to use more than one platform on the same computer, for

Increasing robustness: Platforms run as separate Windows processes limiting the

scope of any problem that might occur.

Providing independence between plant areas that are administered and operated by

different departments

However, exchange of data between components on different URT platforms is

significantly less efficient than exchange of data between components on the same URTplatform, particularly if the platforms are on different computers. Therefore, you should


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2. Platforms2.2. Structure

keep functions that are closely related and that exchange considerable data with each

other on the same URT platform.

2.2 Structure

A platform consists of a tree of component nodes, as shown in the left pane of URT

Explorer.

Each platform consists of

A top component ( icon ) serving only as an attachment point to the platform itself

One or more scheduling modules ( icon)

One or more function blocks under each scheduling module ( icon).

Various types of data items (magenta icons), typically under the function block thatuses them.



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2. Platforms2.3. Operation


Use URT Explorer to see the visual representation of the platform structure. Different

icons are assigned to different types of components.

Components that contain other child components are called container components. URTExplorer shows the container components in the left pane in the form of a tree structure.

The child components of the component selected in the left pane are listed in the right

pane. The right pane includes the non-container components (leaf nodes) as well as thecontainer components that are children of the selected component.

URT places no restrictions on how components are organized in a platform, but only

certain organizations make functional sense based on what a component does.

2.3 OperationCreate

You typically use URT Explorer to create a new platform and configure applications on

it. Applications may also programmatically create platforms for their use.

Save

A platform can be saved at any time to a checkpoint file.

The entire state of the platform, including configuration information and data values, is

captured in the checkpoint file. The platform can be reloaded later from the checkpointfile, for example if the host computer is restarted. The name assigned to the checkpoint

file is the name of the platform.

You must save a newly created platform before it becomes operational. The components

of a platform become operational within the platform as soon as they are added.However, the platform, as a whole, is not available for data connections with other

platforms and for use by other URT subsystems like OPC Server, URT Manager, and

URT Scheduler until it has been saved the first time after it is created. In addition, theplatform has no persistent file from which to reload it until it has been saved.

Run

When a platform starts running, the platform component starts in a Windows process.

The platform then loads itself from the specified checkpoint file and starts running at itslast saved state.

The following methods are available to start running a platform:You can manually start a platform by opening its checkpoint file in URT Explorer,or by requesting URT Manager to start it.


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2. Platforms2.3. Operation


URT Service starts all platforms that are configured for automatic restart when the

platforms host computer starts up.

Once a platform is started, it remains running indefinitely.

Kill

In the context of URT, killing a platform is to completely stop it and shut down itsWindows process. The only way to stop a running platform is to kill it. Of course, when

you shut down the host computer itself, then you also stop the running platform. A killed

platform exists as its last saved checkpoint file.

Client connections

URT Explorer, URT Service, and other clients may connect to a running platform fromtime to time to read and write data, change configuration, etc. When a client disconnects

(such as when URT Explorer exits or closes the platforms file), the platform continues torun in its Windows process and is not affected by the disconnection.


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3. Data Items

3.1 Introduction to Data Items

Data items are similar to variables in a programming language.

The purpose of data items is to expose data in a URT platform tree for following

purposes.

To allow the data to be viewed and entered by external clients, such as URT

Explorer, OPC Server, operator interface, or another client system.

To make the data persistent: Data item values are check pointed whenever a platformis saved so that they can be restored when the platform is reloaded.

To facilitate exchange of data between function blocks or other components: A data

item can be configured to pull or push its value from or to another data item. The

data movement is done in concert with function block execution so that the data is as

fresh as possible.

To provide dynamic indirection: Dynamic indirection allows a function block to

access data (anything from a single value to a large structure) via a reference that can

be changed on the fly.

To associate attributes with a value, such as quality, type, access permissions,reasonable value range, name, description, and so on.

Data items can be added to and deleted from running systems as needed.

Function blocks can create and/or connect to data items and use a data item much the

same as if it were a normal program variable.


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3. Data Items3.2. Types of Data Items


3.2 Types of Data Items

URT supports various types of data items. These include-

Scalars

Strings

Arrays (or vectors), list, queue, and stack.

Multi-dimensional arrays to any level can be formed by creating arrays of arrays

(to any level) of elements.

Structures

Structures and containers can be nested to any level.

URT Explorer uses different icons to represent different data types for better visual

distinction.

3.3 Attributes of Data Items

In addition to Name and Description used to identify a data item, URT data items have

the following attributes.

ConnectionYou can configure a data item to read or write its value(s) from or to any other data item

using the connection property, that is, by specifying path name of the other data and type

of connection (push or pull).

Range

Range of a data item enforces entry of reasonable values, making it impossible for the

data items value to lie outside this range.

Ranges apply only to numerical types of data items, including time and enumerationtypes.


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3. Data Items3.3. Attributes of Data Items


Buffer

Most data item types can optionally maintain three copies of their data: an input buffer,

the working data, and an output buffer.

While the calculations are being done on the working value

Other components can keep writing values to the data item using the input buffer.

Clients can obtain a consistent snap-shot of data items value, without the possibilityof the values changing while the data is being acquired, using the output buffer.

Quality

Each data items value has a quality attribute associated with it. The quality value usesthe convention adopted by the OPC standard for OPC quality flags. Each quality

attribute is a two-byte word with bit fields as defined in the OPC standard.


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R320 Unified Real Time Concepts Guide 29

4. Function Blocks

4.1 Introduction to Function Blocks

Function blocks do the actual work of carrying out the functionality provided by

applications. One or more function blocks together make an application.

URT provides function blocks that are generally needed for platform operations such asscheduling and execution of other function blocks.

Function blocks are executed under a scheduling module. A scheduling module controls

the execution of all components under it.


For information on execution, see Execution".

4.2 Organizing Function Blocks

An application instance may consist of:

A single function block under a scheduling module, or

Several collaborating function blocks under a scheduling module, or

Function blocks under several scheduling modules

Modular organization:

Even within the same scheduling module, if you split your application in several logical

function blocks, you can reuse a function block in more than one context and get thebenefits of modularity.

For example, suppose a single-loop controller includes filtering of the input. You can

either

Implement the filter algorithm and the control algorithm in one function block, or

Implement the filter algorithm and the control algorithm in separate function blocks,

and connect them.

With the second option, you can reuse the filter algorithm with other control algorithms

or other kinds of function blocks that need filtered inputs.

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4. Function Blocks4.3. Organizing Data


To copy the output from the filter to the input of the function block that uses the filtered

value, you need to simply configure a connection.

4.3 Organizing Data

Introduction to organizing data

In general, a function block should create the data items that it uses when it is added to aplatform tree to make it generic.

However, function blocks can use data items anywhere in the platform tree, so there are

many possibilities for organizing data and function block instances. Two possibilities are

briefly discussed in the following sections, Function-centric organizatin and Data-centric organization.

Function-centric organizatin

About funct ion-cent ric organization

In this model, each instance of an application consists of a scheduling module with the

function block (s) under it, and the data used by a function block is placed under the

function block.


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Advantages

Some advantages of this organization are that the scheduling of each instance is

independent, and it is simple to add function blocks that provide optional functionality to

only the instances that require it. This organization will be familiar to control engineerswho have used typical process control systems.



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Scheduling blocks can be hung under the top platform node, function blocks can be hung

under scheduling blocks, and data items can be hung under any of these becausescheduling blocks and function blocks are all derived from a list of component type, so

they can behave as a list.

Data-centric organization

About data-cent ric organization

In this model, an application uses only one instance of a scheduling module with one

instance of the applications function blocks(s) under it. The data may be under this

scheduling module, another scheduling module just for the data, or under the top node

and not under any scheduling module. The data generally consists of a list of structs.Each struct houses all the information for one instance of the functionality. The function

block iterates through the list, and processes each struct that it finds. Adding an instance

consists of adding an additional struct to the list.


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Example of data-centric organization

Consider an application that does calculations for refinery tanks. Each tank has a struct in

the tank list that contains measured inputs for the tank, strapping table data, entered labanalyses, and so on, plus data items to hold calculated results such as volume of stored

material, material balance closure around the tank, indications of inconsistent valve line-

ups, etc. The function block processes the inputs in each tank struct and puts its outputs

in the struct.



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Advantages of data-cent ric organization

An advantage of this organization is the ease of adding or deleting an instance, such as a

tank in the above example.

Configuring data list

The data list in the data-centric organization may need to be under a scheduling modulebecause data items may need to do some processing, such as pulling data from a

connected process input data item or moving data in and out of buffers. If the data items

should be updated at the same interval as the function block calculations, the data list can

be configured under the same scheduling module as the function block. If the data itemsshould be updated at a different interval, perhaps more frequently so an operator can see

process input changes sooner, the data list can be configured under a different scheduling

module.


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5. Commands

5.1 What is a command

URT uses the concept of a command to allow a component to tell the branch below it to

do something. While doing so, the component that issues the command only knows its

immediate children and nothing about what other components are in its branch or howthey are organized.

For example, a Save command is issued at the top node to cause the platform to save its

state to a checkpoint files.

It is not necessary to understand commands to be able to use URT effectively. Operationof commands is described here to provide a little insight into how URT works.

5.2 How does a command work

A command works as follows.

1. A component that wants its branch to do something issues the appropriate commandto each of its child components.

2. Each child component carries out whatever actions it needs to do in response to thecommand, and then in turn issues the command to each of its children.

3. In this way, the command propagates throughout the branch until it reaches all the

leaf nodes.

4. Control returns to the component that originally issued the command. At this point,all the components in the branch headed by the issuing component have had a

chance to take appropriate action for that command.


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6. Execution

6.1 Execution Scheduling

In URT, a scheduling module controls the execution of all components under it.

Execution can be scheduled in different ways.

Interval scheduling A module is executed periodically at a specifiedinterval.

Demand scheduling A module is executed when triggered by a function

block in another module, by an operator, by anexternal client, and so on.

Combination of Interval anddemand scheduling

The module is executed periodically but also can bedemanded at any time.

6.2 Execution Cycle

Overview of execution cyc le

When a scheduling module is executed, either at a scheduled interval or because of a

demand, the scheduling block sends a series of commands that constitute an executioncycle to its branch.

An execution cycle consists of three commands carried out in sequence: PreExecute,

Execute, and PostExecute.

For most function blocks, the execution cycle is completed in the branch headed by thefunction block before going on the next function block. This ensures that data

connections transfer the most recently calculated data. Some function blocks choose a

different execution cycle option so that their PreExecute and PostExecute commands can

run before and after the other function blocks in the module. For more details onexecution cycle scheduling, see URT Programmers Guide.

The actions generally performed in response to the execution cycle commands are as

follows.


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6. Execution6.2. Execution Cycle


PreExecute

A data item does the following in PreExecute:

If it has an input buffer, the data item moves the value from its input buffer to itsworking value

If it has a pull connection, the data item copies to its working value from the output

buffer (or working value if no output buffer) of the connected component.

This ensures that input data is fresh for function block use in Execute.

Function blocks generally do not implement PreExecute.

An exception is the OPC Client function block. It obtains its inputs in PreExecute so thatthey are fresh for other function blocks use in Execute. To ensure that data from OPC

Client is fresh for other function blocks, either

1. The OPC Client function block instance is configured in the same schedulingmodule as the function blocks that use the process input data, or

2. The OPC Client function block is in a scheduling module that is synchronized withthe scheduling module of the function blocks that use the process input data.

Execute

A function block generally performs its main functionality in Execute. Data items do not

implement Execute.

PostExecute

A data item does the following in PostExecute:

If it has an output buffer, the data item copies its working value to its output buffer.

It also copies the working value to the input buffer so that a client only needs toaccess the input buffer for both data entry and data display. However, it does not

copy the working value to the input buffer if a value has been stored to the input

buffer since the input buffer was last copied to the working value, so that inputs arenever lost.

If it has a push connection, the data item copies value of its output buffer (or

working value if no output buffer) to the input buffer (or working value if no input

buffer) of the connected component.

Function blocks generally do not implement PostExecute.


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6. Execution6.3. Execution Thread


An exception is the OPC Client function block. It sends its outputs during PostExecute so

that they can take effect as soon as possible. To ensure that outputs take effect as soon aspossible, either

1. The OPC Client function block instance is configured in the same schedulingmodule as the function blocks that use the process input data, or

2. The OPC Client function block is in a scheduling module that is synchronized withthe scheduling module of the function blocks that use the process input data.

6.3 Execution Thread

Each scheduling module maintains its own thread for execution of the modulescomponents. You can set the execution priority for each scheduling module. You shouldassign lower priorities to applications that have long execution periods and that execute

for a long time, and higher priorities to applications that have short execution periods and

that execute for a short time. In this way, large, processing-intensive applications cancoexist with small, fast-running applications on the same platform.


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7. Messaging

7.1 URT Messaging System

A message generally indicates that an unusual event has just occurred an error,

abnormality, interesting situation, unintended performance, and so on.

The URT messaging system is used to-

Generate messages and keep track of current messages.

Filter out redundant messages.

Log messages.

Send messages to the URT OPC Alarm and Events (A&E) Server.

The message diagram shows a typical message scenario. A message issuer typically a

function block gives the command to issue a specific message based on a message

handle. The Message component finds the message based on the message handle in the

XML formatted message source file, and the message is loaded into the messagecomponent.

To raise the message, the message component - which contains the message is sent to

the message manager. If the message type is Simple, then the message is raisedunconditionally. If the message type is Condition, then the message is only raised if it

has not yet been raised. All raised messages are logged in the Windows Event Log and

the OPC A&E server is informed of the new messages as well.


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7. Messaging7.1. URT Messaging System

(7) Informs A&EClients ofMessage

(5) WritesMessage to xmllog file

(3) Sends Messagecomponent to MessageManager

(2) Message from the xml MessageSource file is loaded into themessage component

(1) Raises a Message basedon a specific messagehandle

MessageIssuer

(10) Notifiedthat ACK hasoccurred

Message ManagerComponent

MessageComponent

MessageSource File

(4)Raise message if message type isSimple or Tracking

Raise message if message type isCondition and message has not yetbeen raised.

URT OPC Alarms andEvents Server

Message log File

(6) Informs A&EServer ofMessage

(9) Notifies thatACK hasoccurred

(8) OperatorAcknowledgesmessage

OPC Alarms andEvents Client (Message

Display)



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7. Messaging7.2. Components of Messaging System


7.2 Components of Messaging System

Message source f ile

Message source files are convenient containers for storing the messages a user may want

to raise. The main advantages of message source files are that no code needs to berecompiled if message text has to change and it promotes localization.

Message source files contain not only the message text, but also many other message

properties related to the message.

Properties of a Message in the Message Source File:

The following list shows the message properties.

Handle

Type

Text

Category

Group

Priority

ConditionName

AckRequired

Message component

The message component is responsible for retrieving a single message from the messagesource file. Typically, this is done by specifying the message handle of the message to

retrieve.

The message and all the messages properties if found are loaded into the message

component. Prior to raising the message, any message property can be modified in codeFor example the message priority can be changed from HIGH (as specified in the

message source file) to LOW, or alternately the message text can be changed, Etc.

Once all the message properties are set appropriately, the message is raised by sendingthe message component (which contains the message) to the message manager.


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Message manager component

About message manager component

Messages are raised via the message manager. The message manager is created by a URT

platform when the platform initializes.

The message manager is the brain of the messaging system as it keeps track of whichmessages need to be raised and which messages need to be cleared for the whole

platform. The message manager logs these messages to the Windows Event Log and

informs the URT OPC A&E server when there are raised or cleared messages.

Message manager also takes care of callbacks associated with messages that require

acknowledgement.

How the Message Manager Decides to Raise and Clear Messages

The message types Condition and Simple have special meanings in the context of

URT messaging. A function block can raise a message anytime that a message triggeringcondition exists. However, if this condition persists for a number of consecutive

executions, the operator should not be bothered with a series of identical messages.

Therefore, if the message type is Condition, the message manager automatically

screens out redundant messages and raises only those messages that are not redundant.However, if the message type is Simple, the message is raised every time the message

triggering condition exists.

The following examples illustrate how the message manager decides to raise and clearmessages, and how to raise messages unconditionally.

Messages of type Condition correspond to the A&E OPC condition event type.

Simple message types correspond to the A&E simple event type.


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Example Message of Type Condition

This example assumes a function block executing at a fixed interval; the function block israising a message of type Condition. Furthermore, a message is raised at interval 1,

stays raised at interval 2, and gets cleared at interval 3.

The most important thing to note is that the message does not get re-raised at interval 2.

Interval Description

1 Function block FB1 raises a message of type = Condition. The handle of

the message is MYCONDITIONMSG.1 Message manager checks the current message queue to determine if FB1

has already raised MYCONDITIONMSG. The manager doesnt find themessage and raises the message. The MYCONDITIONMSG message isput into the current message queue with a status of ACTIVE

1 At the end of interval 1, FB1 sends a ClearAllUnRaisedMessages to themessage manager.

1 The manager loops through the current message queue by FB1 andsearches for messages with a status of NEEDS CLEARING. It doesntfind any, thus no messages are cleared. Then the manager sets the statusof all FB1 messages to NEEDS CLEARING.

2 FB1 re-raises the MYCONDITIONMSG message.

2 Message manager checks the current message queue to determine if FB1has already raised MYCONDITIONMSG. The manager finds the message.The MYCONDITIONMSG message is left in the current message queuebut its status is changed from NEEDS CLEARING to ACTIVE.


2 The manager loops through the current message queue by FB1 andsearches for messages with a status of NEEDS CLEARING. It doesntfind any, so no messages are cleared. Then the manager sets the status ofall FB1 messages to NEEDS CLEARING.

3 FB1 does not raise the MYCONDITIONMSG message.


3 The manager loops through all current messages and determines that theMYCONDITIONMSG message NEEDS CLEARING and thus


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MYCONDITIONMSG is cleared.

Example Message of Type Simple

This example assumes a function block executing at a fixed interval; the function block israising a message of type Simple. Furthermore, a message is raised unconditionally at

interval 1, gets re-raised at interval 2, and is not raised in interval 3.

The most important thing to note is that the message may inundate the message systembecause a new message will be raised every interval the call occurs.


1 Function block FB2 raises a message of type = Simple. The handle ofthe message is MYSIMPLEMSG.

1 Message manager raises the MYSIMPLEMSG message unconditionally.It does not store the message in the current message queue.


1 The manager loops through the current message queue by FB2 andsearches for messages with a status of NEEDS CLEARING. It doesntfind any message, so no messages are cleared.

2 Function block FB2 raises a message of type = Simple. The handle of

the message is MYSIMPLEMSG.

2 Message manager raises the message MYSIMPLEMSG unconditionally.It does not store the message in the current message queue.

2 At the end of interval2, FB2 sends a ClearAllUnRaisedMessages to themessage manager.


3 Function block FB2 does not raise a message.

3 At the end of interval3, FB2 sends a ClearAllUnRaisedMessages to themessage manager.



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Differences between Condition and Simple

The examples clearly illustrate that Simple message can easily inundate the messaging

system with duplicate messages. So typically a function block writer will want to useCondition instead of Simple. Having said this, there are circumstances where using

Simple is totally justified, for example, in initialization code that is only executed once,

etc.

Receiving Notification of an Acknowledgment

In the typical case, the function block that raises a Condition type of message is not

notified of an acknowledgment that occurs at a message display.

For Condition type messages function block a function block can subscribe to themessage manager to be notified of acknowledge event. The AckRequired field of the

condition message will be set to YES to indicate that the condition requires

Acknowledgement. This instructs the message manager and the OPC server to track thecondition accordingly.

Support for raising messages

The methods that function block writers use have been wrapped to make the raising or

clearing of a message simple. The methods do all the dirty work like retrieving the

message from the correct message source file and communicating the message to the

message manager.

Interface with URT OPC Alarms and Events Server

About interface with URT OPC A&E server

The URT OPC A&E server subscribes to URT messages. As a result, all URT messages

are available via URTs OPC A&E server. OPC clients can then hook up to URTs OPCA&E server to retrieve URT messages.

A typical example of this takes place when URT is running on a Honeywell Experion

PKS system. The messaging system of Experion PKS subscribes to URTs OPC A&E

server, and as a result, all URT messages can be viewed via Experion PKSs messagingdisplays.

OPC A&E Event Properties

Sometimes you may want finer control over the value of an A&E property, for example,

you may want to set the severity to a specific value, rather than rely on the severity thatURT assigns a message. Because of this, URT allows you to set A&E event properties

directly.


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Like all other message parameters, A&E properties can be set three ways, via the

message source file, programmatically via the properties on the IUrtMessage interface orprogrammatically via the PutOpcEventStruct method on IUrtMessage. If an A&E

property is not explicitly set, then a default value is provided by the URT messaging

system. For example, you are able to specify the A&E event severity, but if the severity

is not specified, then the severity is derived based on the URTs message category and

priority.

The list of supported A&E properties is: Source, Condition, Message, Type, Category,

Severity, Active Time, Area, Acknowledge required, Cookie, Actor Identifier, Quality,

and State.

In addition, vendor specific Attributes are supported as well.

A&E Vendor Specif ic Attr ibutes (VSAs)

Vendor Specific Attributes (VSAs) are user-defined properties that can be associated

with A&E events. This is a very powerful feature since extra user information can be

configured to be passed along with every event. For example, if a user wants to pass

along the name of the computer where the message originated, then the user mayconfigure a VSA called ComputerName and then set this value for each message.


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8. Process Interface

8.1 Introduction to Process Interface in URT

As URT is designed for building process control applications, it provides for the OPC

standards. URT applications can connect to Honeywell DCS like Experion PKS as well

as any non-Honeywell DCS or process system that supports OPC interfaces.


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8. Process Interface8.2. About OPC

8.2 About OPC

OPC (OLE for Process Control) consists of a set of standards that define COM interfacesto be observed by OPC clients and servers. The COM interfaces are based on Microsoft's

COM/OLE technology.

These standards were established by the OPC Foundation to foster greater

interoperability between automation and control applications, field systems and devices,and business and office applications.

REFERENCE - EXTERNALFor detailed information about OPC, visit the OPC Foundation's Web site,http://www.opcfoundation.org./

OPC provides data from a data source (server) and communicates the data to any client

application in a standard way, thereby eliminating the requirement for an application to

have specific knowledge about a particular data source, such as its internal structure and

communications protocols.

The OPC Data Access Standard does not have a concept of hardware there are just

items (units of data in the data source).

http://www.opcfoundation.org./http://www.opcfoundation.org./


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8. Process Interface8.3. URT OPC Server


8.3 URT OPC Server

URT OPC Server is installed with URT. This application supports the OPC Data AccessVersions 1.0a and 2.2 as well as OPC Alarms and Events Version 1.1 and services all the

platforms running from a particular computer.

URT uses the OPC server interfaces to expose URT platform data to OPC clients. The

OPC clients may require this data for historization, communication with operatorinterfaces, or carrying out the control action initiated by URT based applications.

If an OPC client requests data from a platform that is not currently running, the URTOPC server sends an appropriate error message.

URT supports the area concept as specified by OPC.

8.4 URT OPC Client for Data Access

URT based applications require to collect data from OPC servers of other process controlcomponents.

Data items on a URT platform can be configured to exchange data to the OPC server.

URT provides the OPC Client for Data Access function block which implements theOPC type connections configured on the data items in the scope of its scheduling

module. It discovers all existing OPC type connections when it is added and it is notified

of all changes made to OPC type connections from that point on.

Other function blocks on the URT platform can then use the OPC data by connecting,linking, or directly referring to the data items configured for OPC type connection.


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9. History Collection and Retrieval

9.1 Introduction to History Collection and Retrieval inURT

Many applications require history data for use in a calculation or in a trend display. URT

provides support for this via its history collection and history retrieval components.

These components make it easy to both historize a URT data item, and to retrieve historydata from a historian.

Applications like lab update require this type of functionality whereby an inferred value

must be historized when the lab sample is taken. Then history for the inferred value mustbe retrieved and the inferred value corrected (i.e. biased) when the lab calculation is

available.


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9. History Collection and Retrieval9.2. URT History Collection


9.2 URT History Collect ion

URT uses embedded PHD to do the history collection. Embedded PHD is a lightweightversion of Uniformance PHD that doesnt require Oracle.

Data items on a URT platform can be configured for history collection. URT provides the

Collect History function block which automatically configures embedded PHD to

collect history for the configured data item(s).

9.3 URT History Retrieval

URT based applications retrieve history data from OPC HDA (history) servers. URT

standardized on OPC HDA retrieval because it is supported by most historians, includingPHD, Experion as well as historians supplied by other vendors.

Data items on a URT platform can be configured to retrieve history data from an OPC

HDA server. URT provides the OPC Client for History function block whichimplements history retrieval for the data items in the scope of its scheduling module. It

discovers all existing history retrieval connections when it is added and it is notified of

all changes made to history connections from that point on.

Other function blocks on the URT platform can then use the history data by referring to

the data items configured for history retrieval. Trend displays can also access the history

data in a similar way.

Automatic history can be configured to retrieve either raw or processed history data on ascheduled basis. A function block like lab update can then process the history data.

Alternatively the history retrieval mechanism can be used to set up a connection with an

HDA server, after which HDA methods can be called directly.


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R320 Unified Real Time Concepts Guide 55

10. Security

URT supports security enforcement based on the Experion Process Knowledge System

(EPKS) security model. Each user is assigned a security level and allowed or denied

access to a list of Experion areas. The security levels listed in order of decreasingresponsibility are: MNGR ENGR, SUPR, OPER, and VIEWONLY.

When enabled, security checks are performed for configuration changes and data item

value updates. The security level required for configuration changes is set in the registry

and defaults to ENGR. The security level required for data item value updates is

controlled by the security options of each data item.


For more information about security, see the Profit Suite ImplementationTechnical Reference Guide.

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