Functional Requirements Control Software S_50601-2007

AMERICAN NATIONAL STANDARD

ANSI/ISA-5.06.01-2007

Functional Requirements Documentation for Control Software Applications

Approved 29 October 2007

ANSI/ISA-5.06.01-2007 Functional Requirements Documentation for Control Software Applications

ISBN: 978-1-934394-33-5

Copyright © 2007 by ISA. All rights reserved. Not for resale. Printed in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic mechanical, photocopying, recording, or otherwise), without the prior written permission of the Publisher.

ISA 67 Alexander Drive P.O. Box 12277 Research Triangle Park, North Carolina 27709

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Copyright 2007 ISA. All rights reserved.

Preface

This preface, as well as all footnotes and annexes, is included for information purposes and is not part of ANSI/ISA-5.06.01-2007.

This document has been prepared as part of the service of ISA toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P. O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: [email protected].

The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published by the American Society for Testing & Materials as IEEE/ASTM SI 10-97, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors.

It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards-making process by an individual in no way constitutes endorsement by the employer of that individual, of ISA, or of any of the standards, recommended practices, and technical reports that ISA develops.

CAUTION — ISA ADHERES TO THE POLICY OF THE AMERICAN NATIONAL STANDARDS INSTITUTE WITH REGARD TO PATENTS. IF ISA IS INFORMED OF AN EXISTING PATENT THAT IS REQUIRED FOR USE OF THE DOCUMENT, IT WILL REQUIRE THE OWNER OF THE PATENT TO EITHER GRANT A ROYALTY-FREE LICENSE FOR USE OF THE PATENT BY USERS COMPLYING WITH THE DOCUMENT OR A LICENSE ON REASONABLE TERMS AND CONDITIONS THAT ARE FREE FROM UNFAIR DISCRIMINATION.

EVEN IF ISA IS UNAWARE OF ANY PATENT COVERING THIS DOCUMENT, THE USER IS CAUTIONED THAT IMPLEMENTATION OF THE DOCUMENT MAY REQUIRE USE OF TECHNIQUES, PROCESSES, OR MATERIALS COVERED BY PATENT RIGHTS. ISA TAKES NO POSITION ON THE EXISTENCE OR VALIDITY OF ANY PATENT RIGHTS THAT MAY BE INVOLVED IN IMPLEMENTING THE DOCUMENT. ISA IS NOT RESPONSIBLE FOR IDENTIFYING ALL PATENTS THAT MAY REQUIRE A LICENSE BEFORE IMPLEMENTATION OF THE DOCUMENT OR FOR INVESTIGATING THE VALIDITY OR SCOPE OF ANY PATENTS BROUGHT TO ITS ATTENTION. THE USER SHOULD CAREFULLY INVESTIGATE RELEVANT PATENTS BEFORE USING THE DOCUMENT FOR THE USER’S INTENDED APPLICATION.

HOWEVER, ISA ASKS THAT ANYONE REVIEWING THIS DOCUMENT WHO IS AWARE OF ANY PATENTS THAT MAY IMPACT IMPLEMENTATION OF THE DOCUMENT NOTIFY THE ISA STANDARDS AND PRACTICES DEPARTMENT OF THE PATENT AND ITS OWNER.

ADDITIONALLY, THE USE OF THIS DOCUMENT MAY INVOLVE HAZARDOUS MATERIALS, OPERATIONS OR EQUIPMENT. THE DOCUMENT CANNOT ANTICIPATE ALL POSSIBLE APPLICATIONS OR ADDRESS ALL POSSIBLE SAFETY ISSUES ASSOCIATED WITH USE IN HAZARDOUS CONDITIONS. THE USER OF THIS DOCUMENT MUST EXERCISE SOUND

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PROFESSIONAL JUDGMENT CONCERNING ITS USE AND APPLICABILITY UNDER THE USER’S PARTICULAR CIRCUMSTANCES. THE USER MUST ALSO CONSIDER THE APPLICABILITY OF ANY GOVERNMENTAL REGULATORY LIMITATIONS AND ESTABLISHED SAFETY AND HEALTH PRACTICES BEFORE IMPLEMENTING THIS DOCUMENT.

THE USER OF THIS DOCUMENT SHOULD BE AWARE THAT THIS DOCUMENT MAY BE IMPACTED BY ELECTRONIC SECURITY ISSUES. THE COMMITTEE HAS NOT YET ADDRESSED THE POTENTIAL ISSUES IN THIS VERSION.

The following members of ISA5.6 contributed to the development of this standard:

NAME AFFILIATION

A. Habib, Chair Automation Consultant A. Amdur Consultant D. Beaty DLB Associates P. Blok Pharma Team USA R. Dwiggins Maverick Technologies J. Halajko FMC, Inc. R. Bhala Sanofi Pasteur S. Kolla Bowling Green State University R. Topliff CH2M HILL R. Wood University of Alberta

The following people served as voting members of ISA5:

NAME AFFILIATION

A. Iverson, Chair Ivy Optics T. McAvinew, Managing Director Jacobs Engineering G. Barta Consultant C. Borel Spectrum Engineering Inc. J. Carew Consultant A. Habib Automation Consultant G. Ramachandran Motiva Enterprises LLC

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This standard was approved for publication by the ISA Standards and Practices Board on 17 August 2007.

NAME AFFILIATION

T. McAvinew, Vice President Jacobs Engineering Group M. Coppler Ametek Inc. E. Cosman The Dow Chemical Company B. Dumortier Schneider Electric D. Dunn Aramco Services Co. J. Gilsinn NIST W. Holland Consultant E. Icayan ACES Inc. J. Jamison Jamison & Associates Ltd R. Jones CDI Business Solutions K. Lindner Endress + Hauser Process Solutions V. Maggioli Feltronics Corp. A. McCauley, Jr. Chagrin Valley Controls Inc. G. McFarland Emerson Process Management R. Reimer Rockwell Automation N. Sands E I du Pont H. Sasajima Yamatake Corp. T. Schnaare Rosemount Inc. J. Tatera Tatera & Associates I. Verhappen MTL Instrument Group R. Webb Consultant W. Weidman Parsons Energy & Chemicals Group J. Weiss Applied Control Solutions LLC M. Widmeyer Consultant M. Zielinski Emerson Process Management

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Contents

Preface..........................................................................................................................................................3

1 Scope .................................................................................................................................................11

2 Normative References........................................................................................................................12

3 Definitions/Abbreviations....................................................................................................................13

4 Methodology .......................................................................................................................................14

4.1 Modular plant arrangement........................................................................................................14

Annex A — (informative) Application Example 1: Batch Reactor ...............................................................27

Annex B – (informative) -- Application Example 2: Continuous Distillation Column...................................43

Figure 1 — Charter upon which this standard is based..............................................................................12

Figure 2 — Modular plant partitioning.........................................................................................................15

Figure 3 — Four components of software documentation methodology ....................................................16

Figure 4 — Example of modular plant partitioning and software documentation .......................................17

Figure 5 — Database documentation .........................................................................................................18

Figure 6 — Interlock matrix documentation ................................................................................................21

Figure 7a — Normal sequence matrix ........................................................................................................22

Figure 7b — Hold sequence matrix ............................................................................................................23

Figure 7c — Recipe sequence matrix.........................................................................................................23

Figure 8 — Data security definition.............................................................................................................25

Figure 9 — Chemical reactor P&ID.............................................................................................................27

Figure 10a — Database I/O information .....................................................................................................29

Figure 10b — Database HMI information ...................................................................................................30

Figure 10c — Database operating information ...........................................................................................31

Figure 10d — Control module class definition ............................................................................................32

Figure 11a — Software interlock matrix for Unit R-101 ..............................................................................33

Figure 11b — Software interlock matrix for Equipment Module EM-1........................................................34

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Figure 12a — Normal sequence matrix for Unit R-101...............................................................................36

Figure 12b — Hold sequence matrix for Unit R-101...................................................................................37

Figure 12c — Recipe sequence matrix for R-101.......................................................................................38

Figure 12d — Equipment module sequence matrix for EM-1 phase FILL_R101.......................................39

Figure 13a — Graphic elements .................................................................................................................40

Figure 13b — Interlock status display.........................................................................................................41

Figure 13c — Sequence status display ......................................................................................................41

Figure 14 — Continuous Distillation Column P&ID.....................................................................................44

Figure 15a — Database I/O information .....................................................................................................46

Figure 15b — Database HMI information ...................................................................................................47

Figure 15c — Database operating information ...........................................................................................48

Figure 16 — Interlock matrix .......................................................................................................................49

Figure 17a — Normal sequence matrix for Unit C-104 (URS format) ........................................................51

Figure 17b — Hold sequence matrix for Unit C-104 (URS format).............................................................52

Figure 17c — Sequence matrix for C-104 Startup phase in FRS format (continues on next page)...........53

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Foreword

Learning and configuring today's control software packages is easier than ever before. Documentation, however, is not such an easy task. With the increased capabilities of software packages to handle more process and operator interfaces, the complexity of defining and documenting these requirements increases. This standard directly addresses this documentation issue.

The ISA5.6 subcommittee was established by ISA5, Documentation of Measurement and Control Instruments and Systems, at the request of control systems engineers involved in the automation of plant operations using a wide variety of computer-based platforms. These platforms included distributed control systems, programmable logic controllers and industrialized personal computers offered by a variety of suppliers.

The need for documentation to help define control software prior to hardware selection, especially for batch sequence logic, was identified due to its complexity. ISA's Standards & Practices Board subsequently expanded the scope of ISA5.6 to include the software documentation of continuous processes.

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1 Scope

The scope of this standard is:

• Covers real-time batch, discrete and continuous process automation systems.

• Defines regulatory, event-driven and time-driven control system actions.

• Encompasses both digital and analog control devices in addition to non-control actions (for example, operator messages and batch end reports).

• Encompasses both normal and abnormal operational requirements of systems and shows the interactions between them.

• Uses a set of terms that relate directly to the languages commonly used by plant operators.

• Excludes interactions with higher-level systems.

Within the parameters of this scope, the standard is intended to:

• Establish functional requirements specifications for control software documentation that covers the classes of industrial automation equipment and systems consisting of distributed control systems, programmable controllers and industrial personal computers (see Figure 1).

• Provide techniques for documenting control system software. The software to be generated is a function of the computer system chosen for a particular project. The documentation procedure set forth in this standard is independent of the hardware/software system that is chosen.

• Provide a basis for validation of run-time application software after it is developed and tested to ensure that the initial requirement specification has been met.

The documentation resulting from use of this standard:

• Can be used for control software definition, design, testing and validation.

• Is not intended to require specialized knowledge of any particular engineering or computer science discipline to develop or understand.

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PharmaceuticalPharmaceutical

PowerPower

ChemicalChemical

FoodFood

AutomotiveAutomotive

Many othersMany others

Industrial Industrial ApplicationsApplications

ISAISA--5.06.015.06.01UserUser’’s Softwares SoftwareRequirementsRequirements

DatabaseDatabase

Interlock LogicInterlock Logic

Sequence LogicSequence Logic

ImplementationImplementationLanguagesLanguages

TargetTargetSystemsSystems

Industrial PCIndustrial PC’’ss

ProgrammableProgrammableLogic ControllersLogic Controllers

DistributedDistributedControl SystemsControl SystemsSequential Sequential

Function Function ChartChart

VendorVendorLanguagesLanguages

ProprietaryProprietaryLanguagesLanguages

Relay LadderRelay LadderHumanHuman--Machine Machine

InterfaceInterface

Figure 1 — Charter upon which this standard is based.

2 Normative References

The following normative documents contain provisions that, through reference in this text, constitute provisions of this standard. At the time of publication the editions indicated were valid. All normative documents are subject to revision and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of the IEC and ISO maintain registers of currently valid normative documents.

ANSI/ISA-84.00.01-2004 Parts 1-3 (IEC 61511 Modified), Functional Safety: Safety Instrumented Systems for the Process Industry Sector. www.isa.org .

ISA-88.01-1995, Batch Control Part 1: Models and Terminology. www.isa.org.

ISA-5.5-1985, Graphic Symbols for Process Displays. www.isa.org.

IEC 61131-3 Ed. 2.0: 2003 Programmable controllers - Part 3: Programming languages. www.iec.ch.

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3 Definitions/Abbreviations

3.1 analog input (AI): a modulated signal received by the control system from an external measurement device, such as a 4–20 mA or fieldbus signal from a pressure transmitter.

3.2 analog output (AO): a modulated signal sent by the control system to an external control device, such as an analog 4–20 mA or digital fieldbus signal to a flow control valve.

3.3 control module (CM): the lowest level grouping of equipment in the physical model that can carry out basic control.

NOTE — This term applies to both the physical equipment and the equipment entity.

3.4 detailed design specification (DDS): a separate document that shows how a system functions and meets the requirements laid out in the Functional Requirements Specification prepared from this document.

3.5 discrete input (DI): a binary signal received by the control system from an external switch such as a 24-Vdc or fieldbus signal from a block valve’s closed limit switch.

3.6 discrete output (DO): a binary signal sent by the control system to an external on/off device such as a 120-Vac or digital fieldbus signal to start a pump.

3.7 equipment module (EM): a functional group of equipment that can carry out a finite number of specific minor processing activities. This may exist as part of a unit or as a common resource -- e.g., equipment shared by two or more units.

3.8 functional requirements specification (FRS): a specification listing the detailed operational requirements for a control system (i.e., what the system does, not how it does it).

3.9 operation: a major programmed processing action or set of related actions normally consisting of one or more phases.

3.10 Piping and Instrumentation Diagram (P&ID): a diagram showing the interconnection of process equipment and instrumentation used to control a process.

3.11 Process Flow Diagram (PFD): a diagram showing outlines of one or more pieces of equipment and the expected flow paths for materials and utilities.

3.12 phase: the smallest element of procedural control that can accomplish a process-oriented task. A phase may be comprised of steps.

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3.13 process cell: a logical grouping of equipment that includes the equipment required for production of one or more materials. It defines the span of a logical control of one set of process equipment within an area.

3.14 step: sequential action of control devices within a phase (shown in this standard by a number in parentheses after the status for a discrete device or setpoint for an analog device).

3.15 train: a collection of one or more units and associated lower-level equipment groupings that has the ability to be used to make a quantity of material.

3.16 unit: an equipment grouping to carry out one or more major processing activities such as reaction, crystallization and making a solution. It combines all necessary physical processing and control equipment required to perform those activities as an independent equipment grouping. It is usually centered on a major piece of processing equipment such as a mixing tank or reactor.

3.17 User Requirements Specification (URS): a specification showing the general control requirements for a unit or process cell.

4 Methodology

4.1 Modular plant arrangement

The first step in applying this standard is to divide a process plant into the groupings illustrated in Figure 2. Classes of process units are grouped vertically and trains are grouped horizontally in the figure. Examples of process units include reactors, distillation columns and dryers. A train consists of one or more units necessary to complete the processing step for an intermediate or finished product. This may be as simple as a single mix tank and as complex as a refinery train consisting of multiple reactors, distillation units, dryers, etc. For flexible batch operations we may not be able to define trains other than as individual units. The boxes shown on the periphery of Figure 2 are shared resources comprising additional units and/or equipment modules.

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Gas Waste TreatmentUnits

Train # A B C D ESTORAGE

STORAGE

UTILITIES

PACKAGING

Liquid & Solid Waste Treatment

RawMaterials

ProductShipping

Discharge

Discharge

Figure 2 — Modular plant partitioning

This approach has benefits when configuring both the hardware and the software of a control system. Maximizing the separation of control hardware between trains will minimize the production impact of a hardware failure, while maximizing similarity within each class of process units will minimize implementation costs and human errors in both design and operation. The latter is accomplished by employing reusable design features wherever possible by means of standard class definitions (for units, equipment modules, control modules, etc.) that can be completed and validated for one instance, then copied or instantiated and quickly validated for the remaining members of each class.

Depending on the needs of the design team, the initial design may utilize a User Requirements Specification (URS). This outlines the process control needs for the process cell being designed. A standard Piping and Instrumentation Drawing (P&ID) and instrument index may provide all of the necessary information. Alternatively, more detail as shown on the matrices below may be desired at this stage. The URS is often adequate for review by plant operations, maintenance and process engineering personnel.

After the design basis of the process cell is settled, the basic documentation such as process flow diagram, P&ID, instrument index and preliminary equipment design can be completed. If adequate, as noted above, these will comprise the URS.

The next step is to develop four basic elements of the Functional Requirements Specification (FRS) that describe the instances and detailed requirements for each class of objects so defined (see Figure 3). The Functional Requirements Specification (FRS) is much more detailed and is utilized by instrumentation and system integration personnel as well as during process safety reviews. The four elements of the FRS are:

• Database (instrument tag table)

• Interlock matrix (interlock logic)

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• Sequence matrix (sequence logic)

• Human Machine Interface (HMI)

The first three are commonly prepared using spreadsheet software. The fourth will use graphical software. Examples of each are shown in the examples that follow this description.

D atabaseD atabase

Interlock M atrixInterlock M atrix

Sequence M atrixSequence M atrix

H umanH uman --M achine InterfaceM achine Interface

Figure 3 — Four components of software documentation methodology

Developing these FRS elements assumes that the equipment and processing requirements are well defined. The necessary information can normally be found on various drawings (such as PFDs, P&IDs, and equipment drawings), equipment specifications and data sheets, and other sources. Classes of control objects to supply the required functionality can be developed as needed or drawn from an existing archive.

Figure 4 illustrates the connection between typical units and modules of a partitioned modular plant and the four basic FRS elements. As shown, a single FRS can describe an entire facility or a select subset as required by the project scope. Likewise, certain aspects such as the Sequence matrix may be omitted from the FRS if they are to be deferred to a separate project or provided by a different supplier.

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RawMaterials

Gas Waste TreatmentUnitsTrain

#STORAGE

STORAGE

UTILITIES

PACKAGING

Liquid & Solid Waste Treatment

ProductShipping

Discharge

Discharge

Blender Reactor Centrifuge Dist’n Col’n Dryer

1

2

3

4

BL-101

BL-201

BL-401

RX-102

RX-202

RX-302

CE-103

CE-303

CE-403

DI-104

DI-204

DI-304

DR-105

DR-205

DR-405

DatabaseInterlock MatrixSequence MatrixHuman-Machine Interface

Figure 4 — Example of modular plant partitioning and software documentation

4.1.1 Database

The first part of the documentation is the database, which can be tabulated under various column headings as illustrated in Figure 5. This closely resembles the instrumentation index with provision to record details of Input/Output (I/O) functionality and the parameters required to support operator displays, alarms and control loops. System-dependent implementation details will be defined in the Detailed Design Specification (DDS) which follows later. Though system specific, I/O hardware and software addresses are often considered as a functional requirement because of their potential impact on process availability; as such, they may be designated in the FRS after selection of the control system.

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Figure 5 — Database documentation

The five sections of the database shown in Figure 5 can be consecutive column headings across a spreadsheet. They are shown here as separate sections of the table due to space limitations. In actual use on a spreadsheet they will all follow left to right on one table. The separate sections shown here may be useful for breaking out the table for a printed copy. Leaving this as a continuous spreadsheet will make using it easier. Each row would then show the relevant information for a single instrument or control module; associated alarms may be designated using multiple entries per cell, additional columns or separate tags. This document is the cornerstone of the FRS because it forms the basis or foundation for the other documents that follow. It is applicable for both continuous and batch control but typically contains many more internal variables when applied to a batch process.

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The column names for the database (Figure 5) are suggestions only. Depending on the system, software to be used and other parameters, columns may need to be added, deleted or renamed. The planned uses for each column are:

Basic Point Data

CM Tag: the control module name usually corresponding to the instrument tag number shown on the P&ID, instrument index, etc.

Service: the piece of equipment or module with which the instrument or loop is most closely associated.

Location: the Unit or Equipment Module that includes the Control Module.

P&ID: the Piping and Instrumentation Drawing showing the instrument or loop.

Comments: provides additional information, if needed, for the instrument; may identify special or atypical feature requirements (not used in the examples that follow).

I/O Interface Data

Point Type: indicates the functionality of the item – i.e., discrete vs. analog vs. digital, control vs. alarm, and input vs. output; optionally may refer to a separately specified class of control modules, equipment modules or units.

Device Type: provides additional description of the item such as valve, motor starter, software / function block and may note signal conditioning such as characterization (chr) or square root extraction (√) to be performed within the field device.

Signal Type: shows type of signal for the I/O loop.

Signal Conditioning: shows any adjustments that must be made to the input signal for the desired control action--i.e., pressure or temperature linearization, square-root extraction.

I/O Tags: shows all P&ID tags associated with a particular control module.

I/O Address: hardware or software address information; cabinet location and software identification for troubleshooting, etc.

Human/Machine Interface Data

Scale: the zero and full-scale values or enumerated state descriptors for each signal.

Eng Units: unit descriptor to accompany the value display.

Descriptor: the full description of the instrument or loop for use on alarm and event lists, point details and other displays having sufficient space.

Keywords: the abbreviated description of the instrument or loop for use on group displays and others having limited space.

Data Logging & Archival: This is initially just a “yes/no” flag indicating if this control module should have data logging and/or archiving capability. Later, this can be expanded to show the frequency of these functions.

Operating Data

Alarm Type: identifies the type of each required alarm, such as bad value, high, and hihi for an analog data point or command disagree and un-commanded change for a digital loop.

Alarm Setpoint: the reading values that will activate the alarms, usually just one for each value, but may specify that it will be written or activated by a recipe or sequence logic.

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Alarm Priority: the level of urgency to relay to the operator: different alarms within a loop can have different priorities.

Output Direction: defines the relationship between the controller output and the final control element (direct or reverse).

Controller Type: manual, automatic and supervisory.

Controller Algorithm: proportional, integral, derivative and combinations desired for the control functioning.

Controller Action: direct or reverse action of the controller output in response to the controlled variable--i.e., increasing or decreasing as the process value increases above the setpoint. Note — Data access rights are presented in the HMI data security section while alarm deadbands are typically noted per point only upon exception to a percentage value footnoted on the database table. A further important part of the control database definition is specifying the instance-independent functionality for each class of control modules that will be referenced in the database matrix. A typical definition is illustrated in Figure 10d as part of the first application example. The corresponding control logic can ultimately be configured through any one or more of the following control language types: Boolean, function blocks, structured text, ladder logic and others.

4.1.2 Process Interlock Matrix

Next is the process interlock matrix illustrated in Figure 6. This contains the documentation for all of the process and safety interlocks in a particular section of the plant or project. It may be desirable to keep the safety interlock documentation separate from the process interlocks. Showing both here will help assure that all process concerns are addressed. The purpose here is to document the continuous interlock requirements within the control system regardless of whether the process is continuous or batch. Continuous timed sequences (such as for a sump pump or for baghouse blowdown valves) may be defined here or in the sequence matrix depending upon complexity and safety impact. Product-dependent trip points (such as reactor temperature limits) will normally be identified in the sequence matrix with the associated actions defined either here or in the sequence matrix.

The interlock logic can be described in a simple table listing the interlock numbers taken from the P&ID (piping and instrumentation diagram) or equivalent document along with the initiating device(s) and control device(s). Examples of these include a temperature switch, proximity sensor and block valve.

The P&ID presentation below graphically illustrates the different hardware and software components used to interlock the normal control function (HS-104) with a low level switch (LSLL-101) acting on the final control element (SV-104) using the software logic solver (UC-104).

The company that will be operating the system defines the hazard level. Some examples of hazard levels defined by the potential for material, equipment and personnel loss are shown below. Further information can be found in Guidelines for Safe Automation of Chemical Processes (see section 2), AIChE / CCPS, 1993, www.aiche.org. Guidance for the choice of interlocks, their logic and setting the Safety Integrity Level is found in ANSI/ISA-84.00.01-2004 Parts 1-3 (IEC 61511 Modified), Functional Safety: Safety Instrumented Systems for the Process Industry Sector. www.isa.org .

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INITIATING DEVICE (FAULT)

CONTROL DEVICE (ACTION) ID

NUMBER SET POINTS LOGIC

HAZARD LEVEL

SAFETY INTEGRITY

LEVEL OPERATING

MODE INTERLOCK PURPOSE

Figure 6 — Interlock matrix documentation

Sample Definitions:

Hazard Level: Material Loss Equipment Loss Personnel Loss

(0) None (1) Low Recoverable Repairable Damage Medical Treatment (2) Medium Batch Lost Replace Unit Lost Time Accident (3) High Other Batches Lost Replace Other Units Mult. Injury or Death

ANSI/ISA–5.06.01–2007 — 22 —


Safety Integrity Levels--Examples:

(1) One sensor, one logic solver, one actuator (2) Two sensors, two logic solvers, one actuator (3) Two sensors, two logic solvers, two actuators

Operating Modes

*AR = Automatic reset

*R = Manual reset

*V = Override (with pre-set timer)

*B = Bypass (forcing, testing)

The process safety team should review this simple list before the actual software configuration is developed. These interlocks may be modified based on the results of a hazard analysis for the unit.

4.1.3 Sequence Matrix

The sequence operation of the process is then documented. This may be accomplished with the sequence matrix (see Figures 7a, 7b, and 7c). This information can also be presented using sequential function charts, relay ladder logic and other formats. Here we show the matrix as prepared on a spreadsheet. The sequence matrix has three main sections:

• Normal sequence matrix • Hold sequence matrix • Recipe sequence matrix

Figure 7a — Normal sequence matrix

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Figure 7b — Hold sequence matrix

RECIPE INITIAL OPERATIONS SHUT- CHANGE CONTROL

PARAMETERS PHASE PHASE PHASE PHASE PHASE PHASE DOWN DESCRIPTION DATE BY

PHASE

VARIABLES CODED IN PROGRAM

VARIABLES ENTERED BY OPERATOR

VARIABLES ENTERED BY PRODUCTION SUPERVISOR

Figure 7c — Recipe sequence matrix

A Sequence matrix can be developed for either a continuous or batch process as shown in the examples to follow. It will typically be much simpler for a continuous process and may not have a recipe matrix. The sequence matrix can be used to specify the following types of control requirements:

• State definitions and allowed transitions for control modules (CM), equipment modules (EM), units, or classes of like CM, EM, or units whose instances have been identified in the database and/or interlock matrix (usually oriented toward low-level equipment functions requiring little product-specific knowledge; operators, interlocks or phase logic initiate all state transitions; class definitions should be reusable from project to project).

• Sequence definition and parameter identification for phases or classes of like phases whose instances are identified relative to a particular EM, unit or class of like EM or units referenced in the

ANSI/ISA–5.06.01–2007 — 24 —


database (usually oriented toward minor processing functions requiring little product-specific knowledge; typically interfaces to field devices indirectly by manipulating CM and/or EM states; operators or recipe sequences initiate phase execution; class definitions for common requirements should be reusable from project to project).

• Definition of phase sequencing, equipment requirements/arbitration and process parameters necessary to manufacture each product or class of products (coordinates all product-specific control requirements; operator or higher-level scheduling systems initiate recipe execution)

• Accommodation of both normal and abnormal process conditions for each of the above including hierarchical propagation of consequential actions as needed.

Preparing the product-specific requirements necessitates a detailed knowledge of the operations to be conducted in the subject equipment. Typically, a process write-up or batch sheet and standard operating procedure will provide the necessary knowledge. Using common or generic terms for the phase names will make this document more understandable for others who use it. Sample operation names include: prepare, react, distill, extract, solvent strip, clean and shutdown. Typical phase names include: initial, fill, mix, heat, cure, settle, drain/dump and transfer. The user can employ these or other names as appropriate. These names need to be clearly understood by the plant personnel.

One or more phases may require that multiple actions be completed in order to satisfy the phase requirements. These multiple actions are called steps. All of these steps are typically shown in one column of the spreadsheet. The order in which these must be satisfied is indicated with numbers in parenthesis after the listed action. Where additional distinction between the steps is necessary the column under the phase can be split to show the different steps.

If an equipment module is part of the unit, this will need to be shown in the sequence matrix. If the equipment module is shared by multiple units it will require its own matrix. Otherwise, its phases can be incorporated into the matrix for that unit. Two examples are a heating/cooling system for a reactor jacket and charging manifold with valves and a pump. Using an equipment module may simplify the software programming during integration.

The Normal Sequence matrix (Figure 7a) provides information for all expected usual or routine operations. As indicated, it shows the expected operation of each discrete and analog device associated with the unit. Where there are particular conditions that must be met at the start or end of a phase these should be listed. These conditions include the setpoints of analog controls that must be satisfied as given in the Recipe Sequence below.

Operator messages will appear on the HMI (human-machine interface) to cue an activity by the operator. Batch report variables will be configured into reports to be prepared as hardcopy or electronic media. If manual operations are required to complete the phase, an operator message will cue the personnel and wait for the appropriate response before continuing the phase processing.

Two formats for the Sequence matrix are shown in the examples. The first contains less-detailed information and will often satisfy the needs of the URS. All of the operations, phases and steps can be shown; however, little detail of their functionality is possible here. Each phase occupies a single column in the spreadsheet. This provides a good overview of the control scheme. This does not contain sufficient detail for an instrumentation engineer or system integrator.

The second format provides the level of detail required by these last functions. The information for each phase is detailed over several columns. It can show the details of each control function needed for the system to function. This level of detail is necessary for the FRS and is illustrated for just one of the phases in each example. It also provides the information needed to validate the operation of a control system during start-up.

— 25 — ANSI/ISA–5.06.01–2007


The Hold Sequence (Figure 7b) indicates which conditions are considered to be abnormal by the system and the resulting actions in response to these conditions. If any of the abnormal conditions are met, the system will proceed to the condition shown under Hold Actions and the operator message will be displayed. When the abnormal condition no longer exists the “Recovery” status will be initiated if the system is in full automatic operation.

The Recipe Sequence matrix (Figure 7c) may show general recipe information or have specific information for several recipes to be programmed for that unit. Each parameter needed for a recipe is shown with the permission level required by a person to enter or modify that parameter. Where there are limits on a parameter for a specific phase, this is shown in the appropriate column. This helps prevent entry of wrong values for the parameters.

The allowable modes of operation for each phase include manual and automatic. Under automatic operation, a recipe will proceed without operator interaction unless a hold condition occurs or interaction is required for a particular part of a phase.

4.1.4 Human - Machine Interface (HMI)

ISA-5.5-1985, Graphic Symbols for Process Displays, provides a good starting point in defining the shapes of process equipment for the dynamic graphic displays on operator console screens. It also provides guidelines for use of color for graphic displays. Many hardware vendors have a built-in library of ISA symbols in their graphic display packages.

In addition to displays that usually are supplied as standard with most systems such as controller faceplates, alarm summary displays and trend displays, custom displays may be required to facilitate the operation of a control system. Examples include the interlock and sequence status displays shown in Figures 12b and 12c.

An important part of the HMI definition is setting the data security and access levels. A typical definition is shown in Figure 8. Access needs to be set for different functions in the system such as changing loop set points and changing recipes by various personnel such as operators, supervisors and engineers. For some systems, many more access levels are available. A typical example of this is multiple operator classes with permissions limited by process area(s).

PERSONNEL TYPE FUNCTION

Operator Technician Supervisor Engineer

Controller Tuning NO YES NO YES

Controller SP Change YES YES YES YES

Interlock Setting Change NO YES NO YES

Alarm SP Change NO YES YES YES

Recipe Selection NO NO YES YES

Figure 8 — Data security definition


— 27 — ANSI/ISA–5.06.01–2007


Annex A — (informative) Application Example 1: Batch Reactor

The following chemical reactor example illustrates the application of the methodology to a simple batch process. As the P&ID shows (Figure 9), this reactor will fill multiple materials, heat, mix, and drain material.

REACTORR-101

101

106

105

102

PUMPP-104

LI

HS

TT106

TC

TV106

TAH TAHH

104

DRAIN

STEAM

HS

HS

REACTOR R-1P&ID

DRAWING # P-101

FILL A

FILL B

FILL C

LT101

001

HS

T CONDENSATE

PUMPP-003

003

HSMIXERAG-102ZIC

004A

ZIC

004C

ZIC

004B

HS

004

003

102

104

UC

UC

UC

003

FQC

FV003

002

HS

R-201

101

LSLL

103

LAHH

101

LSL

FT003

UNIT R-101SHARED EQUIPMENT MODULE EM -1

LSHH103

LAH

LSHH-203

I

UNIT R-201

XV001

XV002

I

Note: XV limit switches and pump run indications are not shown here due to space limitations

XV105

Figure 9 — Chemical reactor P&ID

The raw material charging manifold and pump are treated as a shared equipment module (EM-1) because this feed system serves more than one reactor. Accordingly, the phase logic for EM-1 is defined in a separate, small sequence matrix whose operation is triggered by the batch recipe. The HS-004 setpoint, which is also recipe-controlled, determines the proper position switch (ZIC-004A/B/C) alignment and selectively enables the valve position alarms. All valves and other instruments for R-201 and EM-1 are included in the full database matrix.

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The database (Figures 10a, b and c) gives the information for each device on the P&ID in Figure 9. The digital control module classes identified in the “Point Type” column (Figure 10a) are functionally defined by the respective class details shown in Figure 10d.

Initially, the I/O address column in Figure 10a may list only the number and type of connections as shown in Figure 10d. Later, this can be split into multiple columns as required by the system layout and details. These additional columns may show (1) the physical location of the cable connections (cabinet data); (2) the logical connections to other control software; and (3) the software address as appropriate to the control system used for the particular process system.

The HMI information for scale and engineering units (Figure 10b) will come from process information and possibly equipment design limits. The “keyword” is necessary only if the HMI display has an insufficient number of characters for the full length “descriptor.” The alarm function and control loop data (Fig. 10c) will impact the Sequence Matrix inputs. Note that these three sections of Figure 10 will typically appear left to right in a spreadsheet and not as three separate items as shown in this document. This will more clearly show the relationship between the various sets of information. Obviously in this format the first three columns need not be repeated.

Figure 11a illustrates the software interlock matrix for Unit R-101, which provides the following process functionality based on the P&ID:

(a) If the liquid level is too low interlocks UC-102 and UC-104 will shut off the mixer and pump. (b) Interlock UC-104 will prevent the drain pump from operating if the drain valve is closed. (c) Interlock UC-003 shuts down the charging control module when the desired charge quantity has

been satisfied.

The Manual Reset capability for each interlock in this example is provided by de-energizing the associated “Hand Switch” that is normally used to manually change valve position or motor condition. In this way the Hand Switch outputs will not immediately reactivate the interlocked device when the initiating condition clears. Any additional interlocks would be set up the same way. Definitions for the hazard and safety levels are based on the example shown in Figure 6.

Figure 11b illustrates the software interlock matrix for the exclusive use common Equipment Module EM-1 which provides the following functionality based on standard operating practices:

(a) Reinforce the hardwired charge valve interlocks shown on the P&ID by de-energizing the associated Hand Switch when a reactor level exceeds its safe limit, thereby requiring operator intervention (Manual Reset) for charging to resume after the condition clears.

(b) Additional interlocks help to assure integrity of the charge path and measurement of the charged quantity.

CM TAG LOCATION P&ID POINT TYPE ** DEVICE TYPE SIGNAL TYPE I/O TAGS I/O ADDRESSES *

XV-001 R-101 P-101 VLV-FC BALL VALVE 24 VDC

ZSC, ZSO,

XS DI (2), DO (1)

XV-002 R-102 P-101 VLV-FC BALL VALVE 24 VDC ZSC, ZSO,

XS DI (2), DO (1)

HS-003 P-003 P-101 MOTOR PUMP 120 VAC XI, XS DI (1), DO (1)

CORIOLIS / FT FC-003 P-003 P-101 LOOP

GLOBE VALVE 4-20 MA FT, FV AI (1), AO (1)

FQ-003 P-003 P-101 ACCUM - software FC-003.PV

ZIC-004A P-003 P-101 VLV-1 BALL VALVE 24 VDC ZSC DI (1)

ZIC-004B P-003 P-101 VLV-1 BALL VALVE 24 VDC ZSC DI (1)

ZIC-004C P-003 P-101 VLV-1 BALL VALVE 24 VDC ZSC DI (1)

HS-004 P-003 P-101 HS-004 - software ZIC-004A,B,C

LI-101 R-101 P-101 AI RADAR 4-20 MA LT AI (1)

HS-102 AG-102 P-101 MOTOR AGITATOR 120 VAC XI, XS DI (1), DO (1)

LAHH-103 R-101 P-101 ALARM-1 CONDUCTIVITY 24 VDC LSH DI (1)


XV-105 R-101 P-101 VLV-FC PLUG VALVE 24 VDC ZSC, ZSO,

XS DI (2), DO (1)

PT RTD / TT(chr) TC-106 R-101 P-101 LOOP

GLOBE VALVE 4-20 MA TT, TV AI (1), AO (1)

* I/O counts to be replaced by addresses upon system selection and I/O assignment

** Functionality defined by Control Module class definition matrix (Fig. 10d)

Figure 10a — Database I/O information

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SCALE CM TAG LOCATION P&ID

LOW HIGH

ENG.

UNITS DESCRIPTOR KEYWORD

XV-001 R-101 P-101 REACTOR INLET VALVE INLET VALVE

XV-002 R-102 P-101 REACTOR INLET VALVE INLET VALVE

HS-003 P-003 P-101 FILL PUMP MOTOR FILL PUMP

FC-003 P-003 P-101 0 1000 LB/MIN FEED FLOW CONTROLLER FEED CONT.

FQ-003 P-003 P-101 0 30000 LBS FEED TOTALIZING SWITCH FEED TOTAL

ZIC-004A P-003 P-101 FEED MANIFOLD VALVE A FEED VLV A

ZIC-004B P-003 P-101 FEED MANIFOLD VALVE B FEED VLV B

ZIC-004C P-003 P-101 FEED MANIFOLD VALVE C FEED VLV C

HS-004 P-003 P-101 FILL SOURCE SELECTOR FILL SOURCE

LI-101 R-101 P-101 0 100 % REACTOR LEVEL INDICATOR RX LEVEL

HS-102 AG-102 P-101 REACTOR AGITATOR AGITATOR

LAHH-103 R-101 P-101 REACTOR HIHI LEVEL ALARM RX HIHI LVL

HS-104 P-104 P-101 DRAIN PUMP MOTOR DRAIN PUMP

XV-105 R-101 P-101 REACTOR OUTLET VALVE OUTLET VALVE

TC-106 R-101 P-101 70 250 DEGREE C TEMERATURE CONTROLLER TEMP. CONT.

Figure 10b — Database HMI information

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ALARM FUNCTIONS CONTROLLERS CM TAG LOCATION P&ID

TYPE SP PRIORITY

OUTPUT DIRECTION

TYPE ALGORITHM ACTION

XV-001 R-101 P-101 FB_ERR 10 SEC MED DIRECT . . .

XV-002 R-201 P-101 FB_ERR 10 SEC MED DIRECT

HS-003 P-003 P-101 FB_ERR 3 SEC MED DIRECT

FC-003 P-003 P-101 . DIRECT M/A P,I,D REVERSE

FQ-003 P-003 P-101 FQSH RECIPE LOG ONLY

ZIC-004A P-003 P-101 STATE * ** MED

ZIC-004B P-003 P-101 STATE * ** MED

ZIC-004C P-003 P-101 STATE * ** MED

HS-004 P-003 P-101

LI-101 R-101 P-101 LAH LSL

LSLL

85% 10% 3%

MED LOG ONLY LOG ONLY

. . . .

HS-102 AG-102 P-101 FB_ERR 3 SEC MED DIRECT . . .

LAHH-103 R-101 P-101 STATE HIGH . . . .

HS-104 P-104 P-101 FB_ERR 3 SEC MED DIRECT . . .

XV-105 R-101 P-101 FB_ERR 10 SEC MED DIRECT . . .

TC-106 R-101 P-101 TAHH TAH

200 C RECIPE

HIGH MED DIRECT M/A P,I,D REVERSE

* Enabled/disabled by HS-004 according to commanded position

** Set by HS-004 according to commanded position

Figure 10c — Database operating information

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INPUTS CORRESPONDING OUTPUTS CLASS FEATURES

INPUT STATE INPUT 1 INPUT 2 INPUT 3 COMMANDED STATE OUTPUT 1 OUTPUT 2

I/O - ZIC ZSO - XS OPEN OFF ON OPEN ON

CLOSED ON OFF CLOSED OFF MOVING OFF OFF

STATE NAMES

INVALID ON ON ALARM TYPE FB_ERR ALARM IF INPUT STATE DOES NOT TRACK OUTPUT STATE WITHIN 10 SECONDS **

INTERLOCK FORCE CLOSED

VLV-FC

TRIP LOGIC FB_ERR COMMAND CLOSED

I/O - XI - XS RUN ON RUN ON STATE NAMES

STOP OFF STOP OFF ALARM TYPE FB_ERR ALARM IF INPUT STATE DOES NOT TRACK OUTPUT STATE WITHIN 3 SECONDS **

INTERLOCK FORCE STOP

MOTOR

TRIP LOGIC FB_ERR COMMAND STOP

I/O - LSHH LAHH OFF STATE NAMES

NORMAL ON ALARM-1

ALARM TYPE STATE ALARM IF LSHH = OFF I/O - ZIC

OPEN OFF STATE NAMES CLOSED ON

VLV-1

ALARM TYPE STATE ALARM IF ZSC = OFF I/O - ZIC-004A ZIC-004B ZIC-004C

OPEN_A OFF ON ON OPEN_B ON OFF ON OPEN_C ON ON OFF CLOSED ON ON ON

STATE NAMES

MISALIGNED ANY OTHER COMBINATION ENABLE ZIC-004A/B/C ALARMS WHEN HS-003 OUTPUT (DESIRED) STATE IS NOT CLOSED; SET

ALARM STATES OF ZIC-004A/B/C ACCORDING TO HS-004 OUTPUT AS FOLLOWS:

ZIC ON ZIC OFF ZIC OFF OPEN_A ZIC OFF ZIC ON ZIC OFF OPEN_B ZIC OFF ZIC OFF ZIC ON OPEN_C

HS-004

LOGIC FOR ENABLING EXTERNAL

ALARMS

ZIC ON ZIC ON ZIC ON CLOSED

* Identified as “Point Type” in Figure 10a ** Actual timing individually adjustable for each instance

Figure 10d — Control module class definition

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INITIATING DEVICES (FAULT) CONTROL DEVICES (ACTION) ID NUMBER

SETPOINTS LOGIC

HAZARD LEVEL

SAFETY INTEGRITY

LEVEL OPERATING MODE

INTERLOCK PURPOSE

UC-003

{HS-004 CMD = CLOSED *}

OR {HS-004 INPUT = MISALIGNED *} OR

{FQ-003 > RECIPE SP

(FQSH-003 ON)}

STOP P-003

(XS-003 OFF) LOW 1 MANUAL RESET

PREVENT PUMP RUNNING WHEN FEED SOURCE NOT

SELECTED, MISALIGNED, OR CHARGE COMPLETE

UC-102 LI-101 < 10%

(LAL-101 ON)

STOP AG-102

(XS-102 OFF) LOW 1 MANUAL RESET PROTECT AGITATOR

UC-104

{XV-101 CLOSED

(ZIC-101 ON)} OR

{P-104 RUNNING (XS-104 FB ON) FOR 60 SEC WHILE LI-101 < 3% (LALL-101

ON)}

STOP P-104

(XS-104 OFF) LOW 1 MANUAL RESET

PREVENT PUMP RUNNING WHEN VALVE CLOSED OR

REACTOR EMPTY

* Not shown on P&ID

Figure 11a — Software interlock matrix for Unit R-101

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INITIATING DEVICES (FAULT) CONTROL DEVICES (ACTION)

ID NUMBER

SETPOINTS LOGIC

OPERATING MODE INTERLOCK PURPOSE

*

{LAHH-103 IN ALARM (ALSO HARDWIRED***)} OR

{R01.BATCHID <> EM1.BATCHID **} OR {XV-002 OPEN (ZSC-002 OFF)} OR

{HS-004 MISALIGNED (INPUT STATE)}

CLOSE XV-001 (HS-001 OFF)

MANUAL RESET

PREVENT R-101 FROM OVERFLOWING, CONFIRM PROCESS OWNER,

INTEGRITY OF CHARGE MEASUREMENT, AND

PREVENT CHARGING WRONG MATERIAL

*

{LAHH-203**** IN ALARM (ALSO HARDWIRED***)} OR

{R02.BATCHID <> EM1.BATCHID **} OR {XV-002 OPEN (ZSC-002 OFF)} OR

{HS-004 MISALIGNED (INPUT STATE)}

CLOSE XV-002 (HS-002 OFF)

MANUAL RESET

PREVENT REACTOR FROM OVERFLOWING, CONFIRM PROCESS OWNER,

INTEGRITY OF CHARGE MEASUREMENT, AND

PREVENT CHARGING WRONG MATERIAL

*

{XV-001 FB_ERR OR XV-002 FB_ERR (ALARM STATES)} OR

{XV-001 CLOSED AND XV-002 CLOSED (COMMAND STATES)} OR

{HS-004 CLOSED (INPUT STATE)}

STOP P-003 (HS-003 OFF)

MANUAL RESET

INTEGRITY OF CHARGE PATH, PREVENT PUMP RUNNING WITH

DISCHARGE BLOCKED, AND PREVENT PUMP RUNNING WITH INLET

BLOCKED

* P-003 RUNNING (XI-003 ON) START FQC-003

INTEGRATION (FQ-003 ACCUMULATOR)

MANUAL RESET INTEGRITY OF CHARGE MEASUREMENT

* Not shown on P&ID ** BATCHID’s allocated by recipe after confirming EM or unit availability

*** SIL satisfied by hardwired protection; independent software layer provided for proper HS operation. **** LAHH-203 specified separately in R-201 database matrix

Figure 11b — Software interlock matrix for Equipment Module EM-1

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The Sequence Matrix (Figures 12a, b, c) for this relatively simple example can quickly become very involved because of the number of potential interactions among the control entities. To avoid overwhelming complexity, it is imperative to efficiently modularize the sequencing requirements by separating low-level and highly reusable equipment-centric sequences from high-level product-centric requirements. For notational simplicity, the abbreviations OP, SP, and PV are used to denote the output, setpoint, and measured value, respectively, for each loop.

The “Fill” and “Dump” phases in Figure 12a show three steps with their sequence of operation to complete the phase. For the “Fill” phase, the agitator must be stopped, then the outlet valve must be closed; finally, the fill module will operate to permit entry of material. The fill module will not be instructed to operate by the control system until both of the other steps have been completed.

Interruption of a particular phase can result from multiple causes as shown in Figure 12b. Each cause will result in an appropriate alarm message at the operator console. Recovery from this interruption will occur as shown if the control system is in “auto” mode. Otherwise, operator intervention will be required to resume operations.

The “Recipe Matrix” may have very specific values for each recipe parameter or have a range as shown in Figure 12c. If ranges are included, the security level required to enter or change a particular value must be shown in the “Parameter Entered By” column. The recipe to be used for each batch is selected from the options in Figure 12c.

The batch sequence matrix must also contain logic to request allocation of equipment module EM-1 to the batch and, upon acceptance by EM-1, to set its parameters and initiate its phase logic. EM-1 continuously compares its batch assignment with those downstream of XV-001 and XV-002, to determine which one (if either) to enable and which to force closed. The recipe-controlled HS-004 setpoint determines the proper ZIC-004A/B/C permissives to operate the feed pump and alarms if any valve is opened erroneously.

Figures 12a, b, c define the procedural control requirements for Unit R-101 at a suitable level of detail for a User Requirement Specification (URS). The full level of phase specification detail required for a Functional Requirement Specification (FRS) is illustrated in Figure 12d for the exclusive use common Equipment Module’s FILL_R101 phase. The top section shows the final setpoints and initial values for the control modules plus other reference values used during this phase. The bottom section of Figure 12d shows the detailed actions and end conditions for each of the steps referred to above. The text comment gives a good description of the purpose for each step. The step sequence diagram may be included if necessary to illustrate parallel execution paths. The FRS information for R-101 would include a similar level of detail.

It is generally easier to keep all the information clear by stacking the normal, hold, and recipe matrix elements on top of one another in a spreadsheet. This is shown on the matrix for the equipment module (Figure 12d). In certain instances, there may be more than one condition, which would cause a phase to end or a Hold Condition to occur. To clearly show this, split the column under the particular phase and enter both conditions.

OPERATIONS PREPARATION REACTION TRANSFER CLEAN SHUT

PHASES INITIAL FILL HEAT CURE DUMP DOWN

PHASE REF. NO. (1) (2) (3) (4) (5) (6) (7)

CM TAG DESCRIPTION

XV-105 OUTLET VALVE CLOSED CLOSE (2) CLOSE CLOSE OPEN (2) CLOSE (2) / OPEN (4) CLOSE

HS-102 AGITATOR STOPPED STOP (1) RUN RUN STOP (1) RUN (2) STOP

HS-104 DRAIN PUMP STOPPED STOP (1) STOP STOP RUN (3) STOP (1) / RUN (4) STOP

DISCRETE

CONTROL

MODULES

TC-106 BATCH TEMP. RAMP SP: AT 2 DEG/MIN SP = 95C SP= 20C ANALOG

CONTROL MODULES FQ-003 FILL AMOUNT RESET TOTAL=0

ACQUIRED

EQUIPMENT MODULE

PHASES & PARAMETERS

EM1.FILL_R101 N/A

RUN (3);

EM1.BATCHID =

R101.BATCHID;

EM1.RM_SRC =

“XV-002”;

EM1.FQ_TOT.TAR =

R101.RP3.TAR

N/A N/A N/A

RUN (3);

EM1.BATCHID =

R101.BATCHID;

EM1.RM_SRC =

“XV-002”;

EM1.FQ_TOT.TAR =

600 L

N/A

END OF PHASE CONDITIONS IF LI-101 < 1%

AND OPERATOR START BATCH

PV OF FQ-003= RP3 (SEE RECIPE

MATRIX)

PV OF TC-106 = RP1 (SEE

RECIPE MATRIX)

WAIT TIME=RP2 HOURS (SEE

RECIPE MATRIX)

LI-101=<1% PV OF FQ-003= 500 AND TIC = 95C FOR1 HOUR

ALLOWABLE PHASE TRANSITIONS 2 1 &3 4 5 & 3 6 7 1

OPERATOR MESSAGES START NEW BATCH ?? ENTER SP. OF

TC-106

ENTER PHASE DURATION

TIME

N

O

R

M

A

L

S

E

Q

U

E

N

C

E

BATCH REPORT VARIABLES PHASE DURATION PHASE DURATION

TEMP.AT END OF PHASE

PHASE DURATION

Figure 12a — Normal sequence matrix for Unit R-101

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OPERATIONS PREPARATION REACTION END SHUT

PHASES INITIAL FILL HEAT CURE DUMP CLEAN DOWN

PHASE REF. NO. (1) (2) (3) (4) (5) (6) (7)

CM TAG

XV-001

XV-105 OPEN OPEN

HS-102 STOP

DISCRETE

CONTROL

MODULES

HS-104

TC-106 IF >140 C IF >140 C

FQ-003 IF > RP3

ANALOG

CONTROL

MODULES LI-101 > 1 % IF > 5%

ACQUIRED

EQUIPMENT MODULES

EM-1 FILL_R101.HOLD FILL_R101.HOLD

I

N

I

T

I

A

T

I

N

G

C

O

N

D

I

T

I

O

N\

S

ELAPSED TIME IF >30 min IF >2 hr IF >30 min

HOLD ACTIONS

DO NOT PROCEED TO

FILLING PHASE

CLOSE XV-001 SET TC-106

= 60C

SET TC-106

= 60C CLOSE XV-105

OPERATOR MESSAGES EMPTY REACTOR CHECK XV-105 CHECK AG-

102

H

O

L

D

S

E

Q

U

E

N

C

E

RECOVERY RESTART PHASE RESUME PHASE GO TO SHUT-

DOWN RESTART

PHASE RESUME PHASE

Figure 12b — Hold sequence matrix for Unit R-101

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RECIPE RECIPE PRAMETER INITIAL FILL HEAT CURE DUMP SHUT-DOWN

# PARAMETERS(RP) ENTERED BY (1) (2) (3) (4) (5) (6)

FQ-003 (RP3) PROGRAM 1000 L

CURE PHASE TIME (RP2) OPERATOR 1 HR < Y < 2 HR A

TC-106 (RP1) SUPERVISOR 50C< X <90C


CURE PHASE TIME (RP2) OPERATOR 2 HR < Y < 3 HR B

TC-106 (RP1) SUPERVISOR 60C < X <100C


CURE PHASE TIME (RP2) OPERATOR 3 HR < Y < 5 HR

R

E

C

I

P

E

M

A

T

R

I

X

C

TC-106 (RP1) SUPERVISOR 70C < X < 110C

Figure 12c — Recipe sequence matrix for R-101

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PHASE EM1.FILL_ R101

PARAM. SCOPE TYPE / RANGE IDENTIFIER CORRESPONDING

ACTUAL VALUE TEXT EM1.BATCHID

HS004_ENUM EM1.RM_SRC RECIPE-WRITTEN 1000-5000 EM1.FQ_TOT FQ-003.TOTAL IN STEP 8

TIME/DATE START & END TIMES RECORDED AT PHASE START & END REPORT *

TEXT OPER_ID RECORDED IN STEP 8 0-100 EM1.VLV_POS 50 0-150 EM1.FLOW_SP 120 0-500 EM1.PRESET 200 0-50 EM1.TRICKLE 30

PAR

AM

ETER

S

INTERNAL

TEXT EM1.MSG_TEXT " " STEP# DEVICE ACTIONS END CONDITION

XV-002 CLOSED 1 FQ-003 RESET IF HS-001 OFF ZSC-002 ON

HS-004 EM1.RM_SRC

2 OPERATOR MESSAGE

"PREPARE FEED SOURCE “ RM_SRC “ AND ALIGN MANUAL

VALVES"

HS-004.INPUT STATE = COMMANDED STATE

XV-001 OPEN 3 FQ-003 SP=FQ_TOT.TAR; START ZSC-001 OFF

FC-003 MANUAL; OUTPUT = VLV_POS 4 HS-003 RUN XI-003 ON FOR 15 SEC

FC-003 AUTO; SP = FLOW_SP 5 OPERATOR

MESSAGE IF STEP TIME>60 MINS: "CHARGE TIME EXCEEDED: CHECK FLOW"

FQ-003.TOTAL > FQ-003.SP - PRESET

FIC-003 AUTO; SP = TRICKLE

6 OPERATOR MESSAGE

IF STEP TIME>5 MINS: "CHARGE TIME EXCEEDED: CHECK FLOW"

FQ-003.TOTAL > FQ-003.SP

HS-003 STOP 7 FC-003 OUTPUT = 0 WAIT 10 SEC

XV-001 CLOSED HS-004 CLOSED FQ-003 STOP; FQ_TOT.ACT = TOTAL

NO

RM

AL

SEQ

UEN

CE

8 OPERATOR MESSAGE

"CONFIRM CHARGE PROPERLY COMPLETED"

OPER_ID RECORDED WITH MESSAGE CONFIRMATION

DEVICE CONDITION (ACTIVE STEPS) MSG_TEXT VALUE XV-002 FB_ERR AND HS-002 OFF (1-6) "CHECK XV-002 AND"

HS-004 MISALIGNED OR CLOSED (3-6) "CHECK RM MANIFOLD AND"

FB_ERR (3) "CHECK XV-001 AND" XV-001 HS-001 OFF (4-6) "CHECK XV-001 AND" FB_ERR (4) "CHECK HS-003 AND" HS-003 XI-003 OFF (5-6) "CHECK HS-003 AND"

INITIATING CONDITIONS

HMI OPERATOR INITIATED (1-6) "OPERATOR INITIATED -" STEP# DEVICE ACTIONS END CONDITION

HS-003 STOP H1 FC-003 MANUAL; OUTPUT = 0 WAIT 10 SEC

XV-001 CLOSED XV-002 CLOSED HS-004 CLOSED FQ-003 STOP

HO

LD S

EQU

ENC

E

H2

OPERATOR MESSAGE

"HOLDING FILL: "; MSG_TEXT; " CONFIRM WHEN OK TO RESUME"

OPERATOR CONFIRMS MESSAGE

* BESIDES ACTUAL VALUES CORRESPONDING TO EACH RECIPE-WRITTEN VARIABLE

Figure 12d — Equipment module sequence matrix for EM-1 phase FILL_R101

ANSI/ISA–5.06.01–2007 — 40 —


The graphical elements shown in Figure 13a are typical of those available from ISA-5.5-1985, Graphic Symbols for Process Displays. These can generally be added to a display and configured as required to be active elements. The two status displays (Figures 13b & 13c) will quickly show the operator the current condition of each interlock and the progress through a recipe. These are also valuable for troubleshooting when it becomes necessary.

Control Valve

Motor

M

M/AI/B

XM-601

M/A

I/B C/O

XV-501

Manual / Auto

Manual / Auto

Interlock/Bypass

Interlock/Bypass

Show only on failure

Green Red Yellow BlinkingYellow

Open Close Trav el Failure

Green Red BlinkingYellow

Run Stop FailureS/R

Figure 13a — Graphic elements

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I #

1

32

4

5

6

7

AgitatorAg-1

Outlet pumpXM-1

SteamValveTV-1

Initiating Devices

Low Rx level ( <15%)

High Rx Temp.( > 200C)

ARAR ARAR

RR

AR = AUTOMATIC RESETR= MANUAL RESET Common Alarm

Figure 13b — Interlock status display

Operator Message

InitialFillHeatCureDumpShutdown

Parameter Actual Target

Recipe # A

Modes of operationAutomatic

Start PhaseStop Phase

Phases:

Phase Progress

Start SequenceStop Sequence

Catalyst Volume 450 Gal. 500 Gal.

Operation: Reaction

Common Alarm

Manual

Figure 13c — Sequence status display

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Most systems available today have these and many other standard elements built in and ready to use after minimal configuration. Special elements can also be created as needed using CAD software. This should seldom be needed given the large library of control face plates, alarm lists, interlock annunciations, etc.

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Annex B — (informative) Application Example 2: Continuous Distillation Column

The following distillation example illustrates the application of the methodology to a continuous process. The P&ID for this example is shown in Figure 14. The distillation column feed comes from Tank T-101 through an economizer. The reflux is on flow control and the reflux drum level controls the distillate flow. The distillation column pressure is controlled by a vacuum pump. Obviously, many other control schemes are possible and necessary for specific processes. This scheme was chosen only to provide information for this example. Only basic interlocks are shown here. Additional instrumentation and interlocks would be necessary to provide the level of personnel and process safety required by most processes today.

DISTILLATIONCOLUMN

C-104

CONDENSERH-106

REFLUXDRUMT-107

FEED TANKT-101

FEED PUMPP-102

REFLUX PUMPP-110

BOTTOMS PUMPP-111

VACUUM PUMPP-109

FEEDECONOMIZER

H-103

T

CHILLED WATERRETURN

CHILLED WATERSUPPLY

COOLING WATERSUPPLY

COOLING WATERRETURN

HIGH PRESSURESTEAM

STEAMCONDENSATE

LT107

HS110 LV

107

FSL106

TV107

TC107

TT107

PT106

PC106

PV106

LV104

LT104

FV107 FC

107FT107

HS111

FV101

FT101

FC101

LT101

LI101

HS102

HS109FAL

106PAHPAL

LC

LAL107

TT104

FAL101

101LAL

CONTINUOUSDISTILLATION COLUMN

P&IDDRAWING # P-104

VENT CONDENSERH-108

LAH

107

UC110

TV104

LC104

LAL104

TC104

TAHTAL

TT106

TI106

TOUC-104

FROMFAL-106

UC104

UC102

UC111

Figure 14 — Continuous Distillation Column P&ID

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The database (Figures 15a, b, c) gives the information for all devices in the P&ID (Figure 14). The digital control module classes identified in the “Point Type” column (Figure 15a) are functionally defined by the respective class details shown in Figure 10d (see previous example).

I/O address information (Figure 15a) initially will show only the types and number of connections from this control module to the system. When the actual plant layout is known, these can be replaced by columns showing the cabinet and cable connections, software logical connections, and/or software address for the particular process system. This requires some knowledge of the new or existing layouts.

The HMI information for scale and engineering units (Figure 15b) will come from process information and possibly equipment design limits. The “keyword” is necessary only if the HMI display has an insufficient number of characters for the full length “descriptor.”

The alarm function and control loop data (Figure 15c) will impact the Sequence Matrix inputs. This is set up and prepared using the same methodology as for the batch example above.

Figure 16 illustrates the software interlock matrix for Unit C-104, which provides the following process functionality based on the P&ID:

(a) Interlock UC-102 turns off the column feed pump (P-102) when the feed tank (T-101) level drops below 2500 liters. (Turning off this pump will eventually activate UC-104 and UC-111, shutting down the column steam supply and bottoms pump.)

(b) Interlock UC-104 closes the reboiler steam valve (TV-104) if the column level drops below the 5% value or if the condenser cooling water flow slows (FAL-106).

(c) Interlock UC-110 turns off the reflux pump (P-110) when the reflux drum level (LIC-107) reaches 10%.

(d) Interlock UC-111 turns off the bottoms pump (P-111) if the column level drops below the 5% value.

The Manual Reset capability for each interlock in this example is provided by de-energizing the associated “Hand Switch” that is normally used to manually change valve position or motor condition. In this way, the Hand Switch outputs will not immediately reactivate the interlocked device when the initiating condition clears. Any additional interlocks, including those to meet operational requirements and standard operating practice, would be set up the same way. Definitions for the hazard and safety levels are based on the example shown in Figure 6.

CM TAG LOCATION P&ID POINT TYPE ** DEVICE TYPE SIGNAL TYPE I/O TAGS I/O ADDRESSES *

FC-101 T-101 P-104 LOOP ORIFICE / PDT(√); GLOBE VALVE 4-20 MA FT, FV AI (1), AO (1)

LI-101 T-101 P-104 AI PDT 4-20 MA LT AI (1)


LC-104 C-104 P-104 LOOP PDT; GLOBE VALVE FIELDBUS LT,LV AI (1), AO (1)

TC-104 C-104 P-104 LOOP PT RTD / TT(chr); GLOBE VALVE FIELDBUS TT, TV AI (1), AO (1)

FAL-106 H-106 P-104 ALARM-1 FSL 24 VDC FSL DI (1)

PC-106 C-104 P-104 LOOP PT(abs); GLOBE VALVE FIELDBUS PT, PV AI (1), AO (1)

TI-106 C-104 P-104 AI PT RTD / TT(chr) 4-20 MA TT AI (1)

FC-107 T-107 P-104 LOOP PDT; GLOBE VALVE 4-20 MA FT, FV AI (1), AO (1)

LC-107 T-107 P-104 LOOP PDT; GLOBE VALVE 4-20 MA LT, LV AI (1), AO (1)

TC-107 H-106 P-104 LOOP PT RTD / TT(char); GLOBE VALVE 4-20 MA TT, TV AI (1), AO (1)




* I/O counts to be replaced by addresses upon system selection and I/O assignment

** Functionality defined by Control Module class definition matrix (Fig. 10d)

Figure 15a — Database I/O information

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SCALE CM TAG LOCATION P&ID

LOW HIGH

ENG.

UNITS DESCRIPTOR KEYWORD

FC-101 T-101 P-104 10 100 LPM COLUMN FEED RATE FEED FLO

LI-101 T-101 P-104 0 50000 LITER FEED TANK LEVEL FEED LVL

HS-102 P-103 P-104 FEED PUMP FEED PMP

LC-104 C-104 P-104 0 100 % COLUMN BOTTOM LEVEL BOTM LVL

TC-104 C-104 P-104 0 250 Deg. C BOTTOMS TEMPERATURE CONTROL BOTM TMP

FAL-106 H-106 P-104 CONDENSER LOW WATER FLOW CWR FSL

PC-106 C-104 P-104 0 800 mmHg abs COLUMN OVERHEAD PRESS OVHD PRS

TI-106 C-104 P-104 0 250 Deg. C COLUMN OVERHEAD TEMP OVHD TMP

FC-107 T-107 P-104 0 200 LPM REFLUX FLOW RATE RFLX FLO

LC-107 T-107 P-104 0 100 % REFLUX DRUM LEVEL RFLX LVL

TC-107 H-106 P-104 0 250 Deg. C CONDENSATE TEMP COND TMP

HS-109 P-109 P-104 COLUMN VACUUM PUMP VACM PMP

HS-110 P-110 P-104 REFLUX PUMP REFL PMP

HS-111 P-111 P-104 COLUMN BOTTOMS PUMP BOTM PMP

Figure 15b — Database HMI information

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ALARM FUNCTIONS CONTROLLERS CM TAG LOCATION P&ID

TYPE SP PRIORITY

OUTPUT DIRECTION TYPE ALGORITHM ACTION

FC-101 T-101 P-104 FAL 15 HIGH DIRECT M/A/SUP P,I,D REVERSE

LI-101 T-101 P-104

LAH LAL

400002500

HIGH MED

HS-102 P-103 P-104 FB_ERR 3

SEC MED DIRECT M/A

LC-104 C-104 P-104 LAL 10 MED DIRECT M/A/SUP P,I,D DIRECT

TC-104 C-104 P-104

TAH TAL

135 115

MED MED DIRECT M/A/SUP P,I,D REVERSE

FAL-106 H-106 P-104 STATE HIGH

PC-106 C-104 P-104

PAH PAL

120 80

MED MED DIRECT M/A P,I,D DIRECT

TI-106 C-104 P-104

FC-107 T-107 P-104 DIRECT M/A P,I,D REVERSE

LC-107 T-107 P-104 LAL 10 MED DIRECT M/A/SUP P,I,D DIRECT

TC-107 H-106 P-104 REVERSE M/A/SUP P,I,D DIRECT

HS-109 P-109 P-104 FB_ERR 3

SEC MED DIRECT M/A

HS-110 P-110 P-104 FB_ERR 3

SEC MED DIRECT M/A

HS-111 P-111 P-104 FB_ERR 3

SEC MED DIRECT M/A

Figure 15c — Database operating information

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INITIATING DEVICES (FAULT) CONTROL DEVICES (ACTION)

ID NUMBER

SETPOINTS LOGIC

HAZARD LEVEL

SAFETY INTEGRITY

LEVEL OPERATING MODE INTERLOCK PURPOSE

UC-102 LI-101 < 2500 L (LAL-101 ON)

STOP P-102 (HS-102 OFF) LOW 1 MANUAL RESET PROTECT FEED PUMP

UC-104

{FAL-106 IN ALARM (ALSO HARDWIRED)} OR

{LC-104 < 5% (LAL-104 ON)}

CLOSE TV-104 (TIC-104 OUTPUT = 0) MEDIUM 2 MANUAL RESET PROTECT REBOILER &

COLUMN

UC-110 LC-107 < 10% (LAL-107 ON)

STOP P-110 (HS-110 OFF) LOW 1 MANUAL RESET PROTECT REFLUX

PUMP

UC-111 LC-104 < 5% (LAL-104 ON)

STOP P-111 (HS-111 OFF) LOW 1 MANUAL RESET PROTECT BOTTOMS

PUMP

Figure 16 — Interlock matrix

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ANSI/ISA–5.06.01–2007 — 50 —


A continuous process will normally have fewer phases than for batch, if any at all. The sequence matrix for this example is shown in User Requirement Specification (URS) format in Figures 17a and 17b. The sequence of phase commands to control modules is identified by the adjacent numbering. Unless otherwise noted, each step remains active until the corresponding feedback signal confirms the specified action(s). If no sequence numbering exists, the phase comprises a single step in which all specified actions must be confirmed before the system can move to the next phase. All steps must be completed and the “End Of Phase Conditions” satisfied before transitioning to a subsequent phase. For the Drain phase (4), all of the actions with (1) following them are executed as soon as the control system moves to this phase. The other actions then follow in order, pending confirmation of each.

The steps for the Startup phase (2) become very complex for this system. There are actually three parallel paths occurring here. This is best shown in the step sequence diagram at the bottom of Figure 17c. The number sequence shown here can often only be developed after something similar to the step sequence diagram is developed. Path “A” sets up the reboiler and bottoms pump; path “B” starts up the overhead system; while path “C” sets up the feed system. These can proceed independently until all three systems are operating. Only after all three pathways are fully satisfied will the system transition to the “Distill” phase.

The full level of phase specification detail required for a Functional Requirement Specification (FRS) is illustrated for the Startup phase in Figure 17c. The top section shows the final setpoints and initial values for the control modules plus other reference values used during this phase. The step sequence diagram shows the parallel paths used to begin operations for each part of this unit. The bottom section of Figure 17c shows the detailed actions and end conditions for each of the steps referred to above. The text comment gives a good description of the purpose for each step.

The detailed information for the other phases would have a similar appearance. Other formats can also be used to show this information, including sequential function charts, ladder diagrams, and text narratives.

No recipe matrix is included here, as the operating values for a single set of conditions can be entered directly into the “Normal Sequence Matrix.” Once up and running, this process will typically remain in the “Distill” phase for an extended period of time. The “Preparation” and “End” phases are very similar for the batch and continuous processes.

OPERATIONS PREPARATION RUN END PHASES

CONTROL DEVICES

CM TAG KEYWORD

INITIAL (1)

START-UP (2)

DISTILL (3)

DRAIN (4)

CLEAN (5)

SHUTDOWN (6)

HS-102 FEED PMP STOPPED RUN (4C);

STOP (6C) RUN STOP (1) STOP STOP

HS-109 VACM PMP STOPPED RUN (2) RUN STOP (1) STOP STOP

HS-110 REFL PMP STOPPED RUN (5B) RUN STOP (3A) STOP STOP

DISCRETE CONTROL MODULES

HS-111 BOTM PMP STOPPED RUN (5A) RUN STOP (1);

RUN (3B);

STOP (5)

STOP STOP

FC-101 FEED FLO OP = 30 (4C); SP = 75 (5C)

OP = 0 (1) OP = 0

LC-104 BOTM LVL OP = 20 (5A);

SP = 50 (6A)

OP = 0 (1);

WAIT UNTIL

PV < 10 (4)

OP = 0

TC-104 BOTM TMP OP ∝ LIC104 (3A);

SP = 125 (4A) OP = 0 (1) OP = 0

TC-107 COND TMP OP = 100 (1);

SP < 40 (4B) OP = 0 (5) OP = 0

PC-106 OVHD PRS SP = 85 (2) OP = 0 (1) OP = 0

LC-107 RFLX LVL SP > 20 (7B) OP = 0 (1) OP = 0

ANALOG CONTROL MODULES

FC-107 RFLX FLO OP = 20 (5B);

SP = 35 (6B)

OP = 100 (1);

WAIT UNTIL

PV < 10 (2A); OP = 0 (3A)

OP = 0

END OF PHASE CONDITIONS LI-101 > 40,000

ALL PV TARGETS

SATISFIED

OPERATOR INITIATED OR

LI-101 < 1000

ALLOWABLE PHASE

TRANSITIONS 2 3 2, 5 5 6 1, 2

OPERATOR MESSAGES

READY TO START

REDIRECT C104

BOTMS TO BLWDN &

CONFIRM(2B)

Figure 17a — Normal sequence matrix for Unit C-104 (URS format)

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OPERATIONS PREPARATION RUN END

PHASES

CONTROL DEVICES

CM TAG KEYWORD

INITIAL

(1)

START-UP

(2)

DISTILL

(3)

DRAIN

(4)

SHUTDOWN

(4)

CLEAN

(5)

HS-102 FEED PMP STOP

HS-109 VACM PMP STOP

HS-110 REFL PMP STOP

DISCRETE

MODULES

HS-111 BOTM PMP STOP

LI-101 FEED LVL IF PV < 15K IF PV > 2000

FC-101 FEED FLO IF PV < 20

LC-104 BOTM LVL IF PV < 5 IF PV > 1

TC-104 BOTM TMP 120 > PV > 150

TC-107 COND TMP 20 > PV > 40

PC-106 OVHD PRS 75 > PV > 95 IF PV < 125

LC-107 RFLX LVL

ANALOG

MODULES

FC-107 RFLX FLO 25 > PV > 45 IF PV > 0

I

N

I

T

I

A

T

I

N

G

C

O

N

D

I

T

I

O

N

S

ELAPSED TIME

HOLD ACTIONS STOP HS-102, HS-111

OPERATOR MESSAGES PROBLEMS

WITH SYSTEM DRAIN

RECOVERY GO TO

START-UP RESUME

Figure 17b — Hold sequence matrix for Unit C-104 (URS format)

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PHASE C104.STARTUP PARAM. SCOPE

TYPE / RANGE IDENTIFIER CORRESPONDING ACTUAL VALUE DESCRIPTION

0-250 .CW_SP 40 0-400 .PC_SP 85 0-250 .BTM_T_SP 125 0-100 .BTM_L_SP 50 0-200 .RFLX_SP 150 0-100 .OHD_L_SP 50

INTERNAL (FINAL SP)

10-100 .FEED_SP 75 0-100 .CW_INIT 100 0-100 .BTM_L_INIT 20 0-100 .RFLX_INIT 20

INTERNAL (INIT VAL)

0-100 .FEED_INIT 30 0-150 .PIC_HI 95 0-120 .BTM_T_TIMSP 60 0-120 .BTM_L_TIMSP 30 0-100 .BTM_L_LOREF 20 0-100 .BTM_L_LOPB 10 0-100 .BTM_L_HIREF 80 0-100 .BTM_L_HIPB 20 0-100 .BTM_L_HIHI 90 0-100 .BTM_L_DEV 5 0-250 .OVHD_T_INIT 70 0-250 .OVHD_T_NORM 50 0-100 .OVHD_L_LOREF 20 0-100 .OVHD_L_LOPB 10

10-100 .FEED_LO 15

PAR

AM

ETER

S

INTERNAL (REF VAL)

10-100 .FEED_SP_MIN 30

NO

RM

AL

SEQ

UEN

CE

STEP SEQUENCE DIAGRAM

Figure 17c — Sequence matrix for C-104 Startup phase in FRS format (continues on next page)

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PHASE C104.STARTUP STEP# DEVICE ACTIONS END CONDITION COMMENT

1 TC-107 Manual; Output = .CW_INIT FAL-106 not in alarm Start cooling water and confirm flow HS-109 Run 2 PC-106 Auto; SP = .PC_SP HS-109 On and PC-106 < .PC_SP + 20 Start vacuum system, place controller into auto, and

wait for pressure drop Execute startup sequences in parallel for reboiler (3A-6A), overhead (3B-7B), and feed (3C-5C); phase ends after completion of all 3 paths.

TC-104 Manual; continuously calc. Output = 100 * min ((LC104 - .BTM_L_LOREF) / .OVHD_L_LOPB, 1)

OPERATOR MESSAGE "OPEN REBOILER STEAM BLOCK VALVE" 3A

OPERATOR MESSAGE

IF STEP_TIME > .BTM_T_TIMSP MINS: "HEATUP TIME EXCEEDED: CHECK REBOILER"

TC-104 > .BTM_T_SP Set steam rate based on bottoms level until the final temperature SP is reached

TC-104 Auto; SP = .BTM_T_SP 4A OPERATOR

MESSAGE IF STEP_TIME > .BTM_L_TIMSP MINS: "BOTTOM

CHARGE TIME EXCEEDED: CHECK FEED" LC-104 > .OHD_L_SP Set steam rate on temperature control and wait until

the final level SP is reached

HS-111 Run 5A LC-104 Manual; Output = .BTM_L_INIT HS-111 On Start bottoms pump

6A LC-104 Auto; SP = .BTM_L_SP abs(LC104-SP) < .BTM_L_DEV Set bottoms takeoff on level control

3B n/a n/a TI-106 > .OVHD_T_INIT or HS-110 On Wait until reflux pump is on or overhead temperature indicates significant boilup

4B TC-107 Auto; SP = .CW_SP LC-107 > .OVHD_L_LOREF + .OVHD_L_LOPB * .RFLX_INIT / .RFLX_SP

Set cooling water on condensate temperature control and wait for minimum drum level to run pump

HS-110 Run 5B FC-107 Manual; Output = .RFLX_INIT HS-110 On and FC-107 > .FEED_LO Start reflux pump, open valve, and confirm flow

6B FC-107 Auto; continuously calc. SP = .RFLX_SP * min ((LIC107 - .OVHD_L_LOREF) / .OVHD_L_LOPB, 1)

TI-106 < .OVHD_T_NORM and FC-107.SP = .RFLX_SP

Set reflux rate based on drum level until its final flow SP is reached

7B LC-107 Auto; SP = .OHD_L_SP abs(LC107-SP) < .BTM_L_DEV Set overhead takeoff on level control and wait for it to approach SP

3C n/a n/a (HS-110 On and LC-104 < .BTM_L_HIREF -

.BTM_L_HIPB * .FEED_SP_MIN / .FEED_SP) or LC-104 < .BTM_L_SP or HS-102 On

Wait until (a) reflux pump is on and reboiler level not high or (b) reboiler level below SP or (c) feed pump is on

HS-102 Run 4C FC-101 Manual; Output = .FEED_INIT HS-102 On and FC-101 > .FEED_LO Start feed, open valve, and confirm flow

5C FC-101 Auto; continuously calc. SP = max (.FEED_SP_MIN,

.FEED_SP * min ((.BTM_L_HIREF - LC104) / .BTM_L_HIPB, 1))

Cond5C.1: HS-110 On and HS-111 On and FC-101.SP = .FEED_SP

Cond5C.2: LC-104 > .BTM_L_HIHI or HS-102

Off

Set feed rate on bottoms level control until (a) the overhead and bottoms pumps are on and the feed rate is at its final SP (ending the feed sequence) or (b) the feed pump stopped or bottoms level is too high (triggering step 6C)

HS-102 Stop FC-101 Manual; Output = 0

NO

RM

AL

SEQ

UEN

CE

6C OPERATOR MESSAGE "FEED PAUSED ON HIGH BOTTOMS LEVEL"

LC-104 < .BTM_L_LOREF - .BTM_L_LOPB * .FEED_SP_MIN / .FEED_SP

Stop the feed and wait for the bottoms level to drop sufficiently to resume at step 4C

DEVICE CONDITION (ACTIVE STEPS) MSG_TEXT VALUE

INIT

IATI

NG

C

ON

DIT

ION

S

None defined

STEP#

HO

LD

SEQ

UEN

CE

H1

Figure 17c — Sequence matrix for C-104 Startup phase in FRS format (continued from previous page)

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— 55 — ANSI/ISA–5.06.01–2007


Guidelines for specification of graphical elements, illustrated for the batch reactor example (Figures 13a, b, c), apply equally to the continuous distillation column and are not repeated in this example.


Developing and promulgating sound consensus standards, recommended practices, and technical reports is one of ISA’s primary goals. To achieve this goal the Standards and Practices Department relies on the technical expertise and efforts of volunteer committee members, chairmen and reviewers.

ISA is an American National Standards Institute (ANSI) accredited organization. ISA administers United States Technical Advisory Groups (USTAGs) and provides secretariat support for International Electrotechnical Commission (IEC) and International Organization for Standardization (ISO) committees that develop process measurement and control standards. To obtain additional information on the Society’s standards program, please write:

ISA Attn: Standards Department 67 Alexander Drive P.O. Box 12277 Research Triangle Park, NC 27709

ISBN: 978-1-934394-33-5

Documents

Functional Requirements Control Software S_50601-2007