Algorithms Reference

8/19/2019 Algorithms Reference

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Ovation Algorithms Reference Manual

REF_1100

August 2011


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Copyright Notice

Since the equipment explained in this document has a variety of uses, the user and thoseresponsible for applying this equipment must satisfy themselves as to the acceptability of eachapplication and use of the equipment. Under no circumstances will Emerson ProcessManagement be responsible or liable for any damage, including indirect or consequential losses

resulting from the use, misuse, or application of this equipment.

The text, illustrations, charts, and examples included in this manual are intended solely to explainthe use and application of the OvationTM Unit. Due to the many variables associated with specificuses or applications, Emerson Process Management cannot assume responsibility or liability foractual use based upon the data provided in this manual.

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This manual is printed in the USA and is subject to change without notice.

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Copyright © Emerson Process Management Power & Water Solutions, Inc. All rights reserved.

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E-Mail: [email protected]: https://www.ovationusers.com


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Summary o f Changes

Ovation Algorithms Reference Manual REF_1100 August 2011

The August 2011 version of Ovation Algorithms Reference Manual includes miscellaneouscorrections and clarifications to the following algorithms:

BALANCER (see page 81).

DEVICE (see page 126).

DEVICESEQ (see page 146).

FFISEL/FFISELX (see page 627).

LEADLAG (see page 263).

OFFDELAY (see page 313).

ONDELAY (see page 315). ONESHOT (see page 317).


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Contents

1 Introduction to Ovation algorithms 1

1.1 What are algorithms?..........................................................................................................1

2 General algori thm user information 3

2.1 What is hardware addressing for algorithms?.....................................................................3 2.1.1 To determine an algorithm hardware address ..................................................3

2.2 What is propagated point quality?....................................................................................... 4 2.3 Algorithm status and mode settings.................................................................................... 4 2.4 What is invalid number checking and quality checking for algorithms?..............................5

2.5 What are single precision floating point numbers? .............................................................6 2.6 What is the error information generated by algorithms?.....................................................6 2.7 Binary to hexadecimal conversion for algorithms ...............................................................6

3 Understanding tracking 9

3.1 What is tracking?............................................................................................................... 10 3.2 What is the purpose of tracking? ......................................................................................10 3.3 What is the tracking process?...........................................................................................11 3.4 What are the best practices for using tracking?................................................................12 3.5 What algorithms support tracking? ...................................................................................13

3.6 Tracking examples ............................................................................................................15 3.7 Setting tracking signals for algorithms ..............................................................................16

4 Algori thm classificat ions 19

4.1 What are algorithm classification groups? ........................................................................20 4.2 Alarm Manipulation algorithms..........................................................................................21 4.3 Artificial I/O algorithms (signal generators).......................................................................21 4.4 Boolean Logic algorithms..................................................................................................22 4.5 Boolean Logic Memory algorithms....................................................................................23 4.6 Custom Calculation algorithms .........................................................................................23

4.7 Device Control algorithms.................................................................................................24 4.8 Fieldbus algorithms...........................................................................................................25 4.9 Filtering algorithms............................................................................................................ 26 4.10 Hardware Interface algorithms..........................................................................................27 4.11 Link Controller Module Interface algorithms .....................................................................28 4.12 Loop Interface Module algorithms.....................................................................................29 4.13 Mathematical and Statistical algorithms............................................................................ 30 4.14 Modulating Control algorithms ..........................................................................................31


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4.15 Monitor Function algorithms..............................................................................................32 4.16 Operator Interface algorithms ...........................................................................................33 4.17 Point Format Conversion algorithms.................................................................................34 4.18 Pulse Accumulator Module Interface algorithms...............................................................35 4.19 Q-Line Interface algorithms...............................................................................................36

4.20 Redundant Signal Processing algorithms.........................................................................37 4.21 Sequential Logic algorithms..............................................................................................38 4.22 Signal Compensation algorithms ......................................................................................39 4.23 System Diagnostic algorithms...........................................................................................40

4.24 System Time Function algorithms.....................................................................................40

4.25 Time/Counter Function algorithms....................................................................................41 4.26 Tracking algorithms...........................................................................................................42 4.27 Turbine Interface algorithms .............................................................................................43

5 Standard algor ithm reference pages 45

5.1 Using algorithm reference pages ......................................................................................48 5.1.1 Algorithm functional symbols........................................................................... 49

5.2 AAFLIPFLOP ....................................................................................................................50 5.3 ABSVALUE .......................................................................................................................52 5.4 ALARMLIMIT..................................................................................................................... 53 5.5 ALARMMON...................................................................................................................... 58 5.6 ANALOG DEVICE (ADEVICE).......................................................................................... 60 5.7 ANALOGDRUM ................................................................................................................63 5.8 AND................................................................................................................................... 67 5.9 ANNUNCIATOR................................................................................................................ 69 5.10 ANTILOG........................................................................................................................... 72

5.11 ARCCOSINE..................................................................................................................... 74 5.12 ARCSINE ..........................................................................................................................75 5.13 ARCTANGENT .................................................................................................................76 5.14 ASSIGN............................................................................................................................. 77 5.15 ATREND............................................................................................................................ 78 5.16 AVALGEN ......................................................................................................................... 80 5.17 BALANCER....................................................................................................................... 81 5.18 BCDNIN............................................................................................................................. 86

5.19 BCDNOUT......................................................................................................................... 88

5.20 BILLFLOW......................................................................................................................... 90

5.21 BUFFER............................................................................................................................ 92 5.22 CALCBLOCK ..................................................................................................................106 5.23 CALCBLOCKD................................................................................................................ 114 5.24 COMPARE ......................................................................................................................120 5.25 COSINE........................................................................................................................... 121 5.26 COUNTER....................................................................................................................... 122 5.27 DBEQUALS..................................................................................................................... 124 5.28 DEVICE........................................................................................................................... 126


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5.29 DEVICESEQ ...................................................................................................................146 5.30 DEVICEX......................................................................................................................... 150 5.31 DFIELD............................................................................................................................ 170 5.32 DIGCOUNT .....................................................................................................................171 5.33 DIGDRUM .......................................................................................................................173

5.34 DIGITAL DEVICE............................................................................................................178 5.34.1 SAMPLER (Controlled Sampler)...................................................................179 5.34.2 VALVE NC (Non-Controlled Valve)...............................................................181 5.34.3 MOTOR NC (Non-Controlled Motor).............................................................182 5.34.4 MOTOR (Simple Controlled Motor)...............................................................184 5.34.5 MOTOR 2-SPD (Two Speed or Bi-Directional Controlled Motor) .................187 5.34.6 MOTOR 4-SPD (Two Speed and Bi-Directional Controlled Motor) ..............191 5.34.7 VALVE (Controlled Valve) .............................................................................196

5.35 DIVIDE ............................................................................................................................199 5.36 DROPSTATUS................................................................................................................ 202 5.37 DRPI1A ...........................................................................................................................204 5.38 DVALGEN .......................................................................................................................206

5.39 FACEPLATE ...................................................................................................................207 5.39.1 FACEPLATE -- DIGITAL DEVICE template..................................................210 5.39.2 FACEPLATE -- MASTATION template .........................................................214

5.40 FIELD .............................................................................................................................. 215 5.41 FIFO ................................................................................................................................ 217 5.42 FIRSTOUT ......................................................................................................................220 5.43 FLIPFLOP .......................................................................................................................225 5.44 FUNCTION...................................................................................................................... 227 5.45 GAINBIAS .......................................................................................................................231 5.46 GASFLOW ......................................................................................................................235 5.47 HEARTBEAT................................................................................................................... 240

5.48 HIGHLOWMON............................................................................................................... 243 5.49 HIGHMON....................................................................................................................... 244

5.50 HISELECT....................................................................................................................... 245 5.51 HSCLTP ..........................................................................................................................250 5.52 HSLT ............................................................................................................................... 251 5.53 HSTVSVP........................................................................................................................ 252 5.54 HSVSSTP........................................................................................................................ 253 5.55 INTERP ........................................................................................................................... 254 5.56 KEYBOARD ....................................................................................................................258 5.57 LATCHQUAL................................................................................................................... 261 5.58 LEADLAG........................................................................................................................ 263 5.59 LEVELCOMP ..................................................................................................................267 5.60 LOG................................................................................................................................. 271 5.61 LOSELECT...................................................................................................................... 272 5.62 LOWMON........................................................................................................................ 277 5.63 MAMODE ........................................................................................................................278 5.64 MASTATION ...................................................................................................................280 5.65 MASTERSEQ.................................................................................................................. 289


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5.66 MEDIANSEL.................................................................................................................... 300 5.67 MULTIPLY....................................................................................................................... 308 5.68 NLOG .............................................................................................................................. 311 5.69 NOT................................................................................................................................. 312 5.70 OFFDELAY .....................................................................................................................313

5.71 ONDELAY .......................................................................................................................315 5.72 ONESHOT....................................................................................................................... 317 5.73 OR................................................................................................................................... 319 5.74 PACK16........................................................................................................................... 320

5.75 PID .................................................................................................................................. 322

5.76 PIDFF.............................................................................................................................. 337 5.77 PNTSTATUS................................................................................................................... 350 5.78 POLYNOMIAL................................................................................................................. 352 5.79 PREDICTOR ...................................................................................................................354 5.80 PRIORITY Algorithm Package........................................................................................358

5.80.1 PRIORITY...................................................................................................... 359

5.80.2 PRIORITY-EXT .............................................................................................375 5.80.3 PRIORITY-REJ.............................................................................................. 379

5.81 PSLT ...............................................................................................................................382 5.82 PSVS............................................................................................................................... 383 5.83 PULSECNT .....................................................................................................................384 5.84 QAVERAGE .................................................................................................................... 385 5.85 QUALITYMON ................................................................................................................387 5.86 RATECHANGE ...............................................................................................................389 5.87 RATELIMIT...................................................................................................................... 391 5.88 RATEMON ......................................................................................................................394 5.89 RESETSUM ....................................................................................................................396

5.90 RLICONFIG..................................................................................................................... 399 5.91 RPACNT.......................................................................................................................... 402 5.92 RPAWIDTH .....................................................................................................................403 5.93 RSRSTATUS................................................................................................................... 404 5.94 RUNAVERAGE ...............................................................................................................412 5.95 RUNTIME........................................................................................................................ 414 5.96 RVPSTATUS................................................................................................................... 418 5.97 SATOSP.......................................................................................................................... 421 5.98 SELECTOR..................................................................................................................... 422 5.99 SETPOINT ......................................................................................................................424

5.100 SIMTIME .........................................................................................................................427 5.101 SINE................................................................................................................................ 428 5.102 SLCAIN ...........................................................................................................................429 5.103 SLCAOUT .......................................................................................................................432 5.104 SLCDIN ........................................................................................................................... 435 5.105 SLCDOUT .......................................................................................................................439 5.106 SLCPIN ...........................................................................................................................443 5.107 SLCPOUT .......................................................................................................................446


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5.108 SLCSTATUS ...................................................................................................................450 5.109 SMOOTH......................................................................................................................... 454 5.110 SOFTSOE .......................................................................................................................456 5.111 SPTOSA.......................................................................................................................... 466 5.112 SQUAREROOT............................................................................................................... 467

5.113 SSLT ...............................................................................................................................470 5.114 STATISTICS.................................................................................................................... 471 5.115 STEAMFLOW.................................................................................................................. 490 5.116 STEAMTABLE ................................................................................................................492

5.117 STEPTIME ......................................................................................................................495

5.118 SUM ................................................................................................................................ 500 5.119 SYSTEMTIME................................................................................................................. 504 5.120 TANGENT .......................................................................................................................506 5.121 TIMECHANGE ................................................................................................................507 5.122 TIMEDETECT .................................................................................................................508 5.123 TIMEMON .......................................................................................................................510

5.124 TRANSFER..................................................................................................................... 513 5.125 TRANSLATOR ................................................................................................................517 5.126 TRANSPORT ..................................................................................................................521 5.127 TRNSFINDX.................................................................................................................... 523 5.128 TRUTHTBL...................................................................................................................... 524 5.129 TSLH ............................................................................................................................... 527 5.130 TSLP ...............................................................................................................................528 5.131 UNPACK16 .....................................................................................................................529 5.132 VCLTP............................................................................................................................. 531 5.133 VSLT ...............................................................................................................................532

5.134 XOR................................................................................................................................. 533 5.135 X3STEP........................................................................................................................... 534 5.136 2XSELECT...................................................................................................................... 540

6 Q-Line algorithms 547

6.1 What are Q-Line algorithms? ..........................................................................................547 6.2 PVSPSLI ......................................................................................................................... 548 6.3 PWDIN ............................................................................................................................551 6.4 QLIPASS......................................................................................................................... 554 6.5 QPACMD......................................................................................................................... 558

6.6 QPACMPAR.................................................................................................................... 564 6.7 QPASTAT........................................................................................................................ 566 6.8 QSDDEMAND................................................................................................................. 567 6.9 QSDMODE...................................................................................................................... 569 6.10 QSRMA ........................................................................................................................... 570 6.11 QVP................................................................................................................................. 577 6.12 XFLOW............................................................................................................................ 580 6.13 XMA2............................................................................................................................... 587


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6.14 XML2............................................................................................................................... 598 6.15 XPIDSLI........................................................................................................................... 602

7 Foundation Fieldbus algorithms 613

7.1 Ovation Fieldbus algorithms and function blocks............................................................613 7.1.1 STAT bits used with function blocks .............................................................614

7.2 FFAI................................................................................................................................. 615 7.3 FFAO............................................................................................................................... 618 7.4 FFDI ................................................................................................................................ 621 7.5 FFDO............................................................................................................................... 624 7.6 FFISEL/FFISELX ............................................................................................................627 7.7 FFMAI.............................................................................................................................. 635 7.8 FFMAO............................................................................................................................ 638 7.9 FFMDI ............................................................................................................................. 640

7.10 FFMDO............................................................................................................................ 644

7.11 FFPID.............................................................................................................................. 648

8 Understanding the Ovation SIS algorithms 651

8.1 Ovation SIS Logic Solver algorithm table .......................................................................652 8.1.1 Algorithm types..............................................................................................654

8.2 LSAI................................................................................................................................. 655 8.3 LSALM............................................................................................................................. 657 8.4 LSAND ............................................................................................................................659 8.5 LSAVTR ..........................................................................................................................661 8.6 LSBDE............................................................................................................................. 676 8.7

LSBFI ..............................................................................................................................678

8.8 LSBFO............................................................................................................................. 681 8.9 LSCALC ..........................................................................................................................683

8.9.1 LSCALC Expression Editor ...........................................................................687 8.10 LSCEM............................................................................................................................ 697 8.11 LSCMP............................................................................................................................ 723 8.12 LSDI ................................................................................................................................ 725 8.13 LSDO............................................................................................................................... 727 8.14 LSDVC ............................................................................................................................734 8.15 LSDVTR .......................................................................................................................... 746 8.16 LSLIM.............................................................................................................................. 761

8.17 LSMID ............................................................................................................................. 764 8.18 LSNAND.......................................................................................................................... 768 8.19 LSNDE ............................................................................................................................770 8.20 LSNOR............................................................................................................................ 772 8.21 LSNOT ............................................................................................................................774 8.22 LSOFFD ..........................................................................................................................775 8.23 LSOND............................................................................................................................ 777 8.24 LSOR............................................................................................................................... 779


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8.25 LSPDE............................................................................................................................. 781 8.26 LSRET............................................................................................................................. 783 8.27 LSRS............................................................................................................................... 785 8.28 LSSEQ ............................................................................................................................787 8.29 LSSR............................................................................................................................... 790

8.30 LSSTD............................................................................................................................. 792 8.31 LSTP ...............................................................................................................................797 8.32 LSXNOR.......................................................................................................................... 799 8.33 LSXOR ............................................................................................................................ 800

8.34 SIS connector algorithm table.........................................................................................801

8.35 GSECPARAMREF ..........................................................................................................802 8.36 NONSECPARAM ............................................................................................................803 8.37 SECPARAM ....................................................................................................................804 8.38 SECPARAMREF............................................................................................................. 805

9 Migrated special functions 807 9.1 What are migrated special functions?.............................................................................807 9.2 WDPF to Ovation reference table ...................................................................................808 9.3 WDPF special functions to Ovation algorithms...............................................................815 9.4 What are migration algorithms? ......................................................................................821

9.4.1 MODETRANS................................................................................................ 822 9.4.2 SETSTATES.................................................................................................. 823

Index 825


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IN THIS SECTION

What are algorithms? .......................................................................................................... 1

1.1 What are a lgor i t hms?

Algorithms are mathematical formulas that define a specific control strategy. An algorithm may bethought of as a collection of system points that are controlled by the algorithm. The algorithmreads values (inputs) and writes values (outputs) into points to accomplish certain desired actions

in the system. (See Ovation Record Types Reference Manual for information about point recordtypes.)

The Ovation Control Builder places these algorithms on control sheets to tell the Ovation controlsystem what algorithms to use, what points to associate with the algorithms, and in what order thealgorithms should execute. The Control Builder combines multiple algorithms and even multiplecontrol sheets to create an entire control strategy for a system process.

The Ovation algorithms are typically provided with the Ovation Controller, and are used toimplement a wide range of functionality for a Controller. Each algorithm is represented in theControl Builder by a unique symbol.

For information on adding algorithms to sheets in the Control Builder, refer to Ovation Control

Builder User Guide.

S E C T I O N 1

Introduction to Ovation algori thms


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IN THIS SECTION

What is hardware addressing for algorithms?..................................................................... 3 What is propagated point quality?....................................................................................... 4

Algorithm status and mode settings.................................................................................... 4 What is invalid number checking and quality checking for algorithms?.............................. 5 What are single precision floating point numbers? ............................................................. 6 What is the error information generated by algorithms?..................................................... 6 Binary to hexadecimal conversion for algorithms ............................................................... 6

2.1 What is hardware address ing for a lgor i t hms?

Some algorithms (for example, an MASTATION algorithm) require the hardware address of theassociated I/O module in order to perform their functions. You must enter the hardware addressfor the algorithm into the hardware address field.

For a point that is read from or written to an I/O card, the hardware address parameter indicatesthe offset from where the pertinent I/O register resides.

Addressing that is initialized in the algorithm is either for Ovation cards or Q-line cards.

For Ovation, the address is determined by the module position in the I/O cabinet.

For Q-line, the hardware address is equal to the address directly jumpered on the card plusthe offset into the proper channel number (no doubling required).

2.1.1 To determine an algori thm hardware address

1. Access the Point Information window to view the module record (see Ovation OperatorStation User Guide).

2. Select the Hardware tab.

3. Note the hex representation of the hardware address for the module in the “HD” field.

4. The algorithm requires the base address, so take the “D” in the base address and convert it toa zero.

5. Enter that value into the algorithm's hardware address field.

6. For example, if a Loop Interface module record's HD field is “0x9D,” then “0x90” is entered inthe MASTATION'S hardware address field.

S E C T I O N 2

General algorithm user information


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2.2 What is propagated point quality?

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2.2 What is prop agated po in t qua l i ty ?

Many algorithms generate a quality setting for the output. In most cases, the quality of the outputequals the quality of the input. This is commonly called propagated quality. However, this simplepropagation is not true for all algorithms.

In general, the worst quality of the algorithm's input points is passed on to the output point foreach standard algorithm. For example, an input sensor failure causes BAD quality to propagatethrough all standard algorithms that directly or indirectly use the input point. This BAD quality maybe used to reject certain algorithms to Manual mode. (Refer to the individual algorithm referencepages for complete information.)

Process points may have one of the following quality values, assigned by the user or the system:

GOOD = Point is functioning properly.

FAIR = Typically an entered value.

POOR = Generated from certain algorithms if some inputs were BAD and some were GOOD.

BAD = Point is not functioning properly, typically caused by sensor failure.

Note: Algorithms propagate GOOD quality when in Manual mode.

2.3 A lgo r i t hm s ta tus and mode set t ing s

The mode and status digital signals are set as follows:

S I G N A L A C TIO N

Auto Mode MASTATION sets the output Auto Mode signal TRUE when thealgorithm is in Auto mode.

High Limit Reached All algorithms set the High Limit Reached output signal TRUE whenthe output is at the high limit specified and the High Limit Reachedoutput signal is not scan removed.

Local Manual Mode MASTATION sets the Local Manual Mode output signal TRUE whenthe algorithm is in Local Manual mode.

Low Limit Reached All algorithms set the Low Limit Reached output signal TRUE whenthe output is at the low limit specified and the Low Limit Reachedoutput signal is not scan removed.

Manual Mode MASTATION sets the output Manual mode signal TRUE when thealgorithm is in Manual mode.


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2.4 What is invalid number checking and quality checking for algorithms?

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2 .4 What i s inva l id number check ing and qua l i t y check ing fo ra lgo r i thms?

Most algorithms perform invalid number checking on analog input points. These points includetracking inputs. If an invalid number is detected, the drop goes into alarm and the problem isidentified by Fault Code 66, Fault ID 3.

For algorithms, Fault Parameter 3 contains the number of the algorithm sheet detecting an invalidnumber (for Ovation releases 3.1 and above, it contains the svg filename). These numbers arereported as hexadecimal values. The Ovation fault information tool describes fault codes andsuggests possible user actions to correct the fault. To access the Ovation fault information tool,log on to the Ovation/WDPF Users site and click Fault Information Tool in the left hand menu. Or,enter the following URL to log on to the fault information tool directly:

https://www.ovationusers.com/FIT/index.asp

An invalid number is generated under exceptional conditions. An example of such conditions istaking the square root of a negative number. The Function section in the individual algorithmreference sheets identifies those algorithms which provide additional checking to avoid specificexceptional conditions.

When an invalid number is input to an algorithm, generally the output of the algorithm is alsoinvalid and is marked with BAD quality. In the following algorithm reference sheets, eachalgorithm that performs invalid number checking discusses how the invalid number is treated andthe results that occur from the invalid number.

There are three types of invalid numbers: indefinite, NAN, and denormal.

An indefinite invalid number is generated from a mathematical operation for which there is noreasonable result.

A NAN (not-a-number) invalid number is an unrecognizable real number format and shouldnever occur.

A denormal invalid number is generated when the result of a mathematical operation is toosmall to be represented in the 32-bit real number format used in the system. If an analog inputis a denormal invalid number, the drop is placed into alarm identified by Fault Code 66, FaultID 3.

However, certain algorithms store the denormal value into a temporary variable, convert it to zero,and use that value (0) in the algorithm calculation. Consequently, these algorithms calculate avalid output value with GOOD quality and the drop goes into alarm.

If the output of the algorithm is a denormal invalid number, then the value of the output is set tozero and the drop is not placed into alarm. These denormal invalid numbers are displayedthroughout the system as zero.

If an invalid number is generated, the cause of the problem generate should be immediately

investigated and corrected since it could cause a control problem in the system.

In addition to invalid number checking, many algorithms generate a quality setting on the output.


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2.5 What are single precision floating point numbers?

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2.5 What are s ing le prec is i on f loa t in g po in t numb ers?

The Ovation system is limited to single precision floating point numbers which can affect algorithmprecision. In certain cases, this may prevent an algorithm from writing a value beyond a certainnumber if a single precision floating point limitation is reached. Although the internal algorithmcalculation can handle double precision floating point numbers, Ovation points are limited to

single precision values. More information is available by researching the IEEE754 floating pointstandard.

2.6 What is the er ror in fo rmat ion generated by a lgor i t hms?

The second status word in an analog or digital process point may contain error informationgenerated by an algorithm that processed the value of that point.

For analog and digital points, the 2W record field contains the second status word. If a bit isTRUE, then the error indicated by that bit has been detected. If a bit is FALSE, then the error hasnot been detected.

2 .7 B inary to hexadec imal convers ion fo r a lgo r i thms

The following binary to hexadecimal conversion table is included to assist you in using algorithmsthat require binary to hexadecimal conversion.

Binary to Hexadecimal Conversion

B IN AR Y TO HE X A D E C I M A L CO N VER SIO N T A B L E

B I N A R Y HE X A D E C I M A L DEC IMAL

0000 0 0

0001 1 10010 2 2

0011 3 3

0100 4 4

0101 5 5

0110 6 6

0111 7 7

1000 8 8

1001 9 9

1010 A 10

1011 B 11

1100 C 12

1101 D 13

1110 E 14

1111 F 15


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2.7 Binary to hexadecimal conversion for algorithms

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For example, in DIGDRUM, the following binary number represents the states of the 16 outputs ina given step. The right-most bit represents Output 001, and the left-most bit represents Output016. For example, if you want Step 5 to have the outputs in these states, I05 would be initializedto 0x53C6.

Byte = 8 bits, Integer = 16 bits

Binary: 0101 0011 1100 0110 0101001111000110B

Hexadecimal: 5 3 C 6 0x53C6


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IN THIS SECTION

What is tracking?............................................................................................................... 10 What is the purpose of tracking?....................................................................................... 10 What is the tracking process?........................................................................................... 11 What are the best practices for using tracking?................................................................ 12 What algorithms support tracking?.................................................................................... 13 Tracking examples ............................................................................................................ 15 Setting tracking signals for algorithms .............................................................................. 16

S E C T I O N 3

Understanding tracking


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3.1 What is tracking?

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3.1 What is t rack in g?

The tracking function is a sophisticated control feature that is unique to Ovation systems. Trackingis implemented through the signals that connect the algorithms. Tracking may be defined asaligning a portion of a control system which is not in control to the portion of the control systemwhich is in control.

To implement tracking in the Ovation system, tracking signals are sent between algorithms.These signals tell the upstream algorithm whether or not to be in the tracking mode and whatvalue is required by the downstream algorithm to achieve the present output.

Typically, multiple control strategies (or “modes”) are defined to control a process. For example,both manual and automatic control modes may be available. Multiple types of automatic controlmay be available, such as flow control, level control, element control, and cascade control modes.During the transition from one control mode to another, tracking is needed.

When transferring between control strategies (for instance, from manual to automatic controlmodes), information is required by the newly selected control strategy to ensure a smoothtransition. These required values are obtained from the active control strategy and are provided tothe other available strategies. This exchange of information between control strategies is referredto as tracking.

Tracking signals are automatically generated by the Control Builder. The Control Builder assignspoints to carry the tracking mode and value information. The insertion of tracking logic istransparent to the user (requires no user input to implement). You have the option of turningtracking off.

Tracking should be turned off for the following situations:

Tracking from a mathematical calculation.

When using PID to a setpoint to keep from winding up a PID, priority lower/raise. Typically, donot allow tracking to change a setpoint.

Tracking can be blocked in the following ways: Place the algorithms on a separate sheet. Since automatic tracking only occurs within a

sheet, tracking is effectively blocked.

Use Control Builder to remove tracking points from the TRIN entry fields.

3.2 What is the purp ose o f t rack in g?

There are two purposes for tracking:

Prevent bumps.

Changes in the mode of a process have the potential to disrupt the process. For example,consider a situation where a control element is manually set to a low level, even though theautomatic control scheme is calculating a high level. If the control mode is changed toautomatic, a “bump” occurs as this control element’s setting goes from low to high. If thechange is extreme, equipment damage could result. Methods used to avoid this type of rapidadjustment are referred to as “bumpless transfer .”


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3.3 What is the tracking process?

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Reduce process upsets.

A process upset may be defined as a condition in which the control system causes theprocess to temporarily move to an operating point which differs from the desired point. Oftenthe process upset is caused by failing to hold the integral action of a PID Controller in check;this condition is called reset windup.

For example, a PID control scheme sums a Proportional component and an Integralcomponent. In certain situations, the value of the output may reach its limit (100%) while oneof the components is still increasing. Although the output cannot be driven past 100%, it takestime for the component value to return to the appropriate range. During this time, if it isnecessary to lower the output, the artificially high component value can cause a delay. Inorder to keep the control scheme components within the appropriate range, an approachcalled Anti -reset windup l imit ing is used.

To ensure bumpless transfer (during the transition from one control mode to another) and toavoid reset windup, tracking is needed.

3.3 What is the t rack in g proc ess?

Tracking works by reverse calculation of the normal control functions. Control may be thought of

as proceeding from “top to bottom,” with inputs on the top, computations in the middle, andoutputs on the bottom. On the other hand, tracking may be thought of as proceeding from “bottomto top,” with the output values on the bottom being used to calculate values for the computationalelements in the middle. Effectively, tracking calculates a value for an upstream control function,so that the upstream objectives are satisfied.

One output point that is used for tracking is created for each algorithm that has an IN1 input. Theoutput is listed in the algorithm definitions as TOUT. TOUT contains the track output value, modeand status output signals for the cascade IN1 variable.

Some algorithms have two to four additional tracking outputs for the Input 2, Input 3, and Input 4as well. These are TRK2, TRK3, and TRK4.

The tracking output is input by the upstream algorithm as TRIN (Tracking Input Point) accordingto the tracking rules outlined in the following sections. TRIN contains the tracking analog inputvalue and the tracking and limiting mode input signals.

Tracking values are generated by a reverse calculation of the normal algorithm function. That is,when the algorithm is actively controlling the process, it uses one or more inputs to calculate anoutput. When in the tracking mode, the algorithm is provided with the output value, and mustcalculate the input value required to obtain that output. This value is sent to the upstreamalgorithm which is generating the algorithm’s input. When there is more than one input, the valueis sent to the IN1 input.

Not all algorithms initiate tracking. All algorithms do not process the signals the same way. Referto the individual algorithm descriptions to determine how the signals are processed for a particular

algorithm.


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3.4 What are the best practices for using tracking?

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3.4 What are the best prac t ic es for us in g t rack i ng?

Refer to the following guidelines when using tracking:

Tracking is typically done upstream.

Do not unnecessarily use the GAINBIAS algorithm.

Use MAMODE priority raise/lower instead of external transfers below MASTATIONalgorithms.

Tracking signals are always visible (except for BALANCER signals) and are typically shown ingreen.

If downstream tracking can come from more than one source, then the initial building orderdetermines the source unless manually changed. The exception to this is the BALANCERalgorithm, which can accept tracking from up to 16 downstream algorithms.

Tracking may be broken after the signal wires are drawn. On the Solaris platform, this may bedone by clearing the TRIN entry in the algorithm’s EDIT window. On the Windows platform,this may be done with the Clear Tracking icon.

If non-tracking algorithms are inserted between tracking algorithms, then the designer isresponsible for tracking across the “gaps.” Typically, the TRANSFER algorithm is used above

the gap to insert the user-computed tracking. Reset Windup limiting is performed by tracking algorithms if:

They are properly configured for tracking.

The scale limits (TPSC and BTSC) are set to reflect the accepted signal range.

In addition, the PID and PIDFF algorithms provide for enhanced windup limiting in thecascade configuration.

Cross sheet tracking is implemented by passing a tracking point “upstream” through the samepage connectors which pass control signals downstream. On the Solaris platform, this is doneby filling in the optional tracking point name in the cross page connector’s EDIT window. Onthe Windows platform, this is done by using the Set Tracking icon with the signal wires.

Tracking points are fully managed by OCB except when tracking crosses between sheets,and when tracking from a downstream algorithm into a BALANCER algorithm.

Since the BALANCER algorithm tracks from many downstream algorithms, trackingconnections between a BALANCER algorithm and any downstream algorithms are notgraphically visible.

Typically, there is only one tracking input (IN1) to an algorithm, except for TRANSFER andSELECTOR algorithms.

Before you implement tracking, consider the following:

What are scaling factors, voltage, percentage, temperature?

Where is the I/O located?

What is the frequency of the point?

The Track Ramp Rate (TRAT) referred to in the algorithm descriptions is used by thealgorithm when tracking action is terminated and normal control begins. It is the time in unitsper second for the output to decay or ramp to the value dictated by the inputs under normal(non-tracking) operation. The default Track Ramp Rate value is 2.5 units


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3.5 What algorithms support tracking?

REF_1100 13

3 .5 What a lgo r i thms suppor t t rack ing?

Only these algorithms support tracking through dual-purpose analog inputs and outputs (that is,track value in AV field, mode status bits in 3W field) (See Ovation Algorithms Reference Manual and Ovation Record Types Reference Manual.):

Tracking algorithm summary

A LG O R ITH M TRATR A M P

TOUTTO IN1

TRK1TO IN1

TRK2TO IN2

TRK3TO IN3

TRK4TO IN4

A C C EPT TRIN

C A SC A D ETR AC K OPTIMIZE

ANALOGDEVICE

x x

BALANCER x x TRK01-

TRK16

DIVIDE x x x

FIELD x

FFAI x

FFAO x

FFDI x

FFDO x

FFMAI x

FFPID x1 x

FUNCTION x x x

GAINBIAS x x x

GASFLOW x x

HISELECT x x x x x x

LEADLAG x x x

LOSELECT x x x x x x

MASTATION x x x

MULTIPLY x x x

PID x x1 x x

PIDFF x x1 x x

QSRMA x x x RATELIMIT x x

SETPOINT x2 x

SETSTATES x

SQUARE-ROOT

x x x

SUM x x x


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3.5 What algorithms support tracking?

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A LG O R ITH M TRATR A M P

TOUTTO IN1

TRK1TO IN1

TRK2TO IN2

TRK3TO IN3

TRK4TO IN4

A C C EPT TRIN

C A SC A D ETR AC K OPTIMIZE

TRANSFER3 x

4 x x x

XMA2 x x x XML2 x

2 x

X3STEP x x

1 Through S (setpoint) pin

2 Information Only

3 Supports switchable slewing and switchable tracking

4Ramps supported on both TRR1 and TRR2 pins


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3.6 Tracking examples

REF_1100 15

3.6 Trackin g exampl es

Tracking: Mode Transition

One of the most common uses of tracking is during the transition between manual mode and automode. In this case, the control algorithm upstream of the MASTATION algorithm must be tracked

to the current output of the MASTATION algorithm. The input to the MASTATION station is thesame as the output from the MASTATION station at the moment of the mode change, andbumping is prevented.

Tracking: SUM Algor ithm

Another common use of tracking is for one input into a SUM algorithm. A two-input SUM algorithmnormally adds two inputs, A and B, to produce an output, C. That is, A + B = C. When thealgorithm is in tracking mode, C is dictated by downstream tracking requirements and one of theinputs which may be continually varying as process conditions change. Therefore, a value for theother input must be calculated by the algorithm such that the sum of the inputs is equal to therequired output. Simple algebraic manipulation of the SUM equation reveals that the dependentinput must be tracked to the difference between required C and independent B. That is, A = C - B.

Tracking: PID Algor ithm

Still another common tracking use involves one of the inputs to a PID algorithm’s error calculation.As in the SUM example, the output of the PID is dictated by downstream tracking requirementsand the process variable acts as an independent variable. However, because integral action isinvolved in this control algorithm, the concept for tracking changes. Here, the appropriatetechnique is to cause a zero error to be presented to the PID during tracking periods to provide noerror-related movement of the PID output when tracking is initially released.

Therefore, the dependent input to the PID error function, the set point, should be tracked to thevalue of the process variable input so that a zero-error condition is produced. Also, the PID outputmust be tracked when the associated portion of the system is not in control so that integral actiondoes not cause process upsets by following set point errors. As described previously, thiscondition is called reset windup.

Typically, an MASTATION algorithm is placed below the PID algorithm on a control sheet.

In summary, in a plant, there might be a change in a process value (for example, the temperaturerose in a feedwater system). The applicable process control sheet contains the logic that definesthe desired value for the process. The algorithm PID looks at the difference between the actualprocess value and the desired process value and reacts based on this difference. It performs thenecessary action (for example, add cold water to lower the water temperature) to bring theprocess back to the desired value.

Tracking: Reset Windup

The concept of reset windup applies to normal control modes as well as to tracking modes. It isundesirable to allow the integral action in a control algorithm to move any further in a directionwhich tends to drive a control element past its limits of travel. Once the integrator winds pastwhere it should be, it takes time to wind back to the control region when the time comes. Controldelays result and process upsets may occur. The solution is to compute an integrator outputwhich keeps the downstream demand to the control element at the limit until it becomes time todrive the control element into the control range. This approach is called anti-reset windup limiting.


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3.7 Setting tracking signals for algorithms

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Tracking: Anti-Reset Windup

The Ovation tracking functions performs the anti-reset windup limiting function if the following twoconditions are met:

The sheets must be configured using the Ovation sheet tracking rules.

The Scale Top and Scale Bottom parameters of the algorithms must be set to reflect theactual control element ranges, usable controller ranges, and so forth.

The fact that an algorithm is at its top or bottom of scale is used to produce signals which inhibitthe upstream algorithm from moving too far in the wrong direction. If algorithms are properlyconfigured, reset windup is prevented. Reset windup is technically more of a concern in controlmode than in tracking mode.

3 .7 Set t ing t rack ing s igna ls fo r a lgo r i thms

The digital tracking signals are set and used as described in the following table.

S I G N A L A C TIO N O F TH E A LG O R ITH M I N IT IAT IN GTH E TR A C K I N G

IMPLEMEN TATIO N BY TH E

A LG O R ITH M B EIN G TO LD TOTR AC K

Track PID and PIDFF set the Track output signalTRUE.

TRANSFER sets the Track output signalTRUE for the value that is not selected.

MASTATION set the Track output signalTRUE for one loop after it reads thehardware value on the first pass.MASTATION sets the Track output signalTRUE when the algorithm is not in Automode.

All algorithms set the Track output signalTRUE when the Track input signal isTRUE.

The output value is set equal to theTrack input value. An internal trackbuffer is set up to provide a bumplesstransfer when the Track input signal isremoved.

Track-if-Lower HISELECT sets the Track-if-Lower outputsignal TRUE for the value that is notselected only when there are no Track,Track-if_Higher, or Track-if-Lower inputsignals and the gain on the input value ispositive.

LOSELECT sets the Track-if-Lower outputsignal TRUE for the value that is notselected only when there are not Track,Track-if-Higher, or Track-if-Lower input

signals and the gain on the input value isnegative.

If the output value of the PID orPIDFF is less than the Track inputvalue, then a negative error causesthe Controller to take action from theprevious output value, and a positiveerror causes the Controller to takeaction from the Track input value.


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REF_1100 17


IMPLEMEN TATIO N BY TH E A LG O R ITH M B EIN G TO LD TOTR AC K

All algorithms set the Tack-if-Lower outputsignal TRUE when there is no Track inputsignal and either:

The Track-if-Lower signal is TRUE andthe gain on the input value is positive, or

The Track-if-Higher input signal is TRUEand the gain on the input value isnegative.

Track-if-Higher LOSELECT sets the Track-if-Higher outputsignal TRUE for the value that is notselected only when there are no Track,Track-if-Higher, or Track-if-Lower inputsignals and the gain on the input value ispositive.

HISELECT sets the Track-if-Higher outputsignal TRUE for the value that is notselected only when there are no Track,Track-if-Higher, or Track-if-Lower inputsignals and the gain on the input value isnegative.

All algorithms set the Track-if-Higher outputsignal TRUE when there is no Track inputsignal and :

The Track-if-Higher input signal is TRUEand the gain on the input value ispositive, or

The Track-if-Lower input signal is TRUEand the gain on the input value isnegative.

If the output value of PID or PIDFF isgreater than the Track input value,then a positive error causes theController to take action from theprevious output value, and a negativeerror causes the Controller to takeaction from the Track input value.

Lower Inhibit PID and PIDFF set the Lower Inhibit outputsignal TRUE when the algorithm is inCascade mode, no Track input signalexists, and:

The Track-if-Lower input signal is TRUEand either the gain on the setpoint ispositive with INDIRECT action on theerror or the gain on the setpoint isnegative with DIRECT action on the error,or

The Track-if-Higher input signal is TRUEand either the gain on the setpoint isnegative with INDIRECT action on theerror, or the gain on the setpoint ispositive with DIRECT action on the error.

The output is prevented fromdecreasing its value, but it ispermitted to increase.


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IMPLEMEN TATIO N BY TH E A LG O R ITH M B EIN G TO LD TOTR AC K

All algorithms set the Lower Inhibit outputsignal TRUE when there is no Track inputsignal and:

The output value is at the low limitspecified and the gain on the output valueis positive, or

The output value is at the high limitspecified and the gain on the input valueis negative, or

The Lower Inhibit input signal is TRUEand the gain on the input value ispositive, or

The Raise Inhibit input signal is TRUEand the gain on the input value isnegative.

Raise Inhibit PID and PIDFF set the Raise Inhibit outputsignal TRUE when the algorithm is inCascade mode, no Track input signalexists, and:

The Track-if-Higher input signal is TRUEand either the gain on the setpoint ispositive with INDIRECT action on theerror, or the gain on the setpoint isnegative with DIRECT action on the error,or

The Track-if-Lower input signal is TRUEand either the gain on the setpoint isnegative with INDIRECT action on theerror, or the gain on the setpoint ispositive with DIRECT action on the error.l

The output is prevented fromincreasing its value, but it is permittedto decrease.

All algorithms set the Raise Inhibit outputsignal TRUE when there is no Track inputsignal, and:

The output value is at the high limitspecified and the gain on the input valueis positive, or

The output value is at the low limitspecified and the gain on the input valueis negative, or

The Raise Inhibit input signal is TRUEand the gain on the input value ispositive, or

The Lower Inhibit input signal is TRUE

and the gain on the input value isnegative.


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REF_1100 19

IN THIS SECTION

What are algorithm classification groups? ........................................................................ 20 Alarm Manipulation algorithms.......................................................................................... 21 Artificial I/O algorithms (signal generators)....................................................................... 21 Boolean Logic algorithms.................................................................................................. 22 Boolean Logic Memory algorithms.................................................................................... 23 Custom Calculation algorithms ......................................................................................... 23 Device Control algorithms ................................................................................................. 24 Fieldbus algorithms ........................................................................................................... 25 Filtering algorithms............................................................................................................ 26 Hardware Interface algorithms.......................................................................................... 27 Link Controller Module Interface algorithms ..................................................................... 28 Loop Interface Module algorithms..................................................................................... 29 Mathematical and Statistical algorithms............................................................................ 30 Modulating Control algorithms .......................................................................................... 31 Monitor Function algorithms.............................................................................................. 32 Operator Interface algorithms ........................................................................................... 33 Point Format Conversion algorithms................................................................................. 34 Pulse Accumulator Module Interface algorithms............................................................... 35 Q-Line Interface algorithms............................................................................................... 36 Redundant Signal Processing algorithms ......................................................................... 37 Sequential Logic algorithms.............................................................................................. 38 Signal Compensation algorithms ...................................................................................... 39

System Diagnostic algorithms........................................................................................... 40 System Time Function algorithms..................................................................................... 40 Time/Counter Function algorithms.................................................................................... 41 Tracking algorithms........................................................................................................... 42 Turbine Interface algorithms ............................................................................................. 43

S E C T I O N 4

Algorithm classifications


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4.1 What are algorithm classification groups?

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4.1 What are a lgor i t hm c lass i f ica t ion grou ps?

Most algorithms can be classified according to their function. Many algorithms can be placed inmore than one category because they can have multiple applications.

All the Ovation algorithms are listed in the following sections. This includes the standard

algorithms as well as the Foundation Fieldbus and Q-Line algorithms. Reference pages (see page48) are provided for each algorithm.

Alarm manipulation algorithms (see page 21)

Artificial I/O algorithms (Signal Generators) (see page 21)

Boolean logic algorithms (see page 22)

Boolean logic memory algorithms (see page 23)

Custom calculation algorithms (see page 23)

Device control algorithms (see page 24)

Fieldbus algorithms (see page 25)

Filtering algorithms (see page 26)

Hardware interface algorithms (see page 27) Link Controller module interface algorithms (see page 28)

Loop interface module algorithms (see page 29)

Mathematical and statistical algorithms (see page 30)

Modulating control algorithms (see page 31)

Monitor function algorithms (see page 32)

Operator interface algorithms (see page 33)

Point format conversion algorithms (see page 34)

Pulse accumulator module interface algorithms (see page 35)

Q-Line algorithms (see page 36)

Redundant signal processing algorithms (see page 37) Sequential logic algorithms (see page 38)

Signal compensation algorithms (see page 39)

System diagnostic algorithms (see page 40)

System time function algorithms (see page 40)

Time/counter function algorithms (see page 41)

Tracking algorithms (see page 42)

Turbine interface algorithms (see page 43)


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4.2 Alarm Manipulation algorithms

REF_1100 21

4.2 A larm Manipu la t ion a lgor i t hms

Description

Alarm manipulation algorithms provide a means of interfacing alarm information into the controlscheme.

Common uses

Alarm manipulation algorithms have the following uses:

Drive alarm panels.

Determine alarm states to trigger control functions.

Commonly used algorithms of this type

ALARMLIMIT (see page 53) -- allows logic to be driven using alarm limits and valuesproduced by analog points.

ALARMMON (see page 58) -- monitors up to 16 analog or digital points for alarm states.

ANNUNCIATOR (see page 69) -- calculates alarm state. SOFTSOE (see page 456) - allows a Sequence of Events (SOE) to be generated by software

in control sheets.

4.3 Ar t i f i c i a l I /O a lgor i t hms (s igna l generator s)

Description

Artificial I/O algorithms generate a value and serve as place holders to input values into thesystem.

Common uses

Artificial I/O algorithms have the following uses:

Provide an interface for operator value entry.

Input fixed constants into the control scheme.

Change the point name of a signal.


ASSIGN (see page 77) -- transfers the value and quality of one process point to anotherprocess point of the same type.

AVALGEN (see page 80) -- analog value generator.

DVALGEN (see page 206) -- digital value generator.


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4.4 Boolean Logic algorithms

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4.4 Bool ean Log i c a lgor i t hms

Description

Boolean logic algorithms represent logical gates for binary logic (1 or 0).

AND - all inputs must be true to get true output. Implement as normally open contacts in a series.

OR - One or more inputs must be true to get true output. Implement as normally open contacts inparallel.

NOT - inverts the input. Implement with normally closed contacts.

XOR - inputs must be different from each other to get true output. For example, out = (A AND(NOT B)) OR ((NOT A) AND B).

Common uses

Boolean logic algorithms have the following use:

Implement functions in binary logic.


AND (see page 67) -- logical AND gate up to eight inputs.

NOT (see page 312) -- logical NOT gate.

OR (see page 319) -- logical OR gate up to eight inputs.

TRUTHTBL (see page 524) - condenses discrete logic elements (for example, AND, OR,NOT, XOR, NAND, or NOR) into one algorithm call.

XOR (see page 533) -- exclusive OR of two inputs.


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4.5 Boolean Logic Memory algorithms

REF_1100 23

4.5 Bool ean Log i c Memory a lgor i thms

Description

Boolean logic memory algorithms remember the state of the input change.

Common uses

Boolean logic memory algorithms have the following uses:

Implement on/off switches to initiate start/stop functions.

Latch binary outputs.

Implement toggle switches.


AAFLIPFLOP (including alternate implementations) (see page 50) -- alternate action flip-flopwith reset.

FLIPFLOP (see page 225) -- S-R type flip--flop memory with set or reset override.

4.6 Custom Calcu l a t ion a lgor i t hms

Description

Custom calculation algorithms support complex mathematical equations within a single algorithm.These algorithms can be used to simplify mathematical processes instead of using separatemathematical function algorithms.

Common uses

Custom calculation algorithms have the following uses:

Enter mathematical functions and utilize the result in the control scheme.

Convert gray codes to actual rod positions.


CALCBLOCK (see page 106) -- allows you to define a mathematical calculation using a list ofoperators.

CALCBLOCKD (see page 114) -- operates like CALCBLOCK, but is used for logical functionsonly (digital version).

DRPI1A -- digital rod position indicator.


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4.7 Device Control algorithms

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4.7 Dev ice Cont ro l a lgor i t hms

Description

Device control algorithms are predefined control schemes used to quickly implement start/stop,open/close logic.

Common uses

Device control algorithms have the following uses:

Start/stop motors.

Open/close valves, dampers, etc.

Calculate running time.


ANALOG DEVICE (ADEVICE) (see page 60) - interfaces to Motor Control Centers (MCCs).

DEVICE (see page 126) - combines the commands to open/close/stop or start/stop a piece ofequipment with feedback signals indicating the command was accomplished.

DEVICEX (see page 150) - combines the commands to open/close or start/stop a piece ofequipment with feedback signals indicating the command was accomplished.

DIGITAL DEVICE (see page 178) - provides logic to control the following seven types ofdevices:

MOTOR (see page 184) - simple controlled motor.

MOTOR NC (see page 182) -- non-controlled motor.

MOTOR 2-SPD (see page 187) - two-speed or bi-directional controlled motor.

MOTOR 4-SPD (see page 191) - two-speed and bi-directional controlled motor.

SAMPLER (see page 179) - controlled sampler (calculates running time).

VALVE (see page 196) - controlled valve.

VALVE NC (see page 181) - non-controlled valve.


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4.8 Fieldbus algorithms

REF_1100 25

4.8 F ie ldbus a lgor i t hms

Description

Fieldbus algorithms interface to Fieldbus function blocks. Function blocks are self-containedsoftware modules that reside in Fieldbus devices. Therefore, Fieldbus devices can be controlled

by Ovation Fieldbus algorithms and integrated as part of an Ovation control scheme.

Common uses

Fieldbus algorithms have the following use:

Implement Foundation Fieldbus logic at the transmitter level.


FFAI (see page 615) - Foundation Fieldbus analog input.

FFAO (see page 618) - Foundation Fieldbus analog output.

FFDI (see page 621) - Foundation Fieldbus digital input.

FFDO (see page 624) - Foundation Fieldbus digital output. FFMAI (see page 635) - Foundation Fieldbus multiple analog input.

FFMAO (see page 638) - Foundation Fieldbus multiple analog output.

FFMDI (see page 640) - Foundation Fieldbus multiple digital input.

FFMDO (see page 644) - Foundation Fieldbus multiple digital output.

FFPID (see page 648) - Foundation Fieldbus PID.

FFISEL (see page 627) - Foundation Fieldbus input selector.


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4.9 Filtering algorithms

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4.9 F i l te r ing a lgor i t hms

Description

Filtering algorithms stabilize I/O readings. In most cases, they are used to filter out noise orcompensate for a true delay.

Common uses

Filtering algorithms have the following uses:

Smooth noisy signals.

Compute averages.

Compensate for transport delays.

Implement derivative functions in the control scheme.


LEADLAG (see page 263) -- lead/lag compensator.

QAVERAGE (see page 385) - average N analog points; exclude points with Bad quality; N <9.

RATELIMIT (see page 391) - rate limiter with fixed rate limit and flag when rate limit isexceeded.

RUNAVERAGE (see page 412) - running average transform.

SMOOTH (see page 454) - smoothed value transform.

TRANSPORT (see page 521) - transport time delay.


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4.10 Hardware Interface algorithms

REF_1100 27

4.10 Hardware In ter face a lgor i t hms

Description

Hardware interface algorithms read and/or write data to/from I/O modules or field devices.

Common uses

Hardware interface algorithms have the following uses:

Interface to a specific type of hardware.

Allow monitoring and diagnosing of output signal status.

Perform digital positioning of control devices.


ANALOG DEVICE (ADEVICE) (see page 60) - interfaces to local analog loop Controllers.

ATREND (see page 78) - trend an analog or digital point.

FIELD (see page 215) - write value to a hardware output point. DFIELD (see page 170) - used only with hardware digital output variable points.

RPACNT (see page 402) - count pulses from the Pulse Accumulator card.

RPAWIDTH (see page 403) - pulse width from the Pulse Accumulator card.

RSRSTATUS (see page 404) - interface to the RSR card.

RVPSTATUS (see page 418) - reads the Value Positioner card status and information.

X3STEP (see page 534) - acts as a positioner control for field devices.

Also see Link Controller module interface algorithms (see page 28).


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4

Documents

Algorithms Reference