achieving target control performance using fieldbus devices achieving target control performance...

Achieving Target Control Achieving Target Control Performance UsingPerformance Using

Fieldbus Fieldbus DevicesDevices

[File Name or Event]Emerson Confidential27-Jun-01, Slide 2

PresentersPresenters

• Terry Blevins

• Marcos Peluso

• Dan Christensen


IntroductionIntroductionIntroductionIntroduction

• Overview – FF Block• Applications that May be Addressed

– Single loop feedback control– Feedforward control– Cascade control– Interlock, Input selection, Flow integration, Calculations and characterization

• Control Performance– Variation if Block Execution Time– Impact of Device Response Time and Slot Time– What determine Macrocycle– Example – Single Loop

• Splitting Control Between Fieldbus and the Control System– Impact on delay on loop response, guidelines– Future – Assigning blocks to execute in DeltaV H1 card– Future – Viewing Execution Schedule

• Summary• References


FF Function BlocksFF Function BlocksFF Function BlocksFF Function Blocks

• AI – Analog Input

• AO – Analog Output

• PID – PID Control

• DI – Discrete Input

• DO – Discrete Output

• ISEL – Input Selector

• ARITH– Arithmetic

• SC – Signal Characterizer

• INT – Integrator

• MAI – Multiple Analog Input

• MAO – Multiple Analog Output

• MDI – Multiple Discrete Input

• MDO – Multiple Discrete Output

Function Blocks Addressed by FF Interoperability Function Blocks Addressed by FF Interoperability Testing, v4.5Testing, v4.5


Applications that may be addressed Applications that may be addressed using FF function block capabilityusing FF function block capability

Applications that may be addressed Applications that may be addressed using FF function block capabilityusing FF function block capability

• Single loop feedback control

• Feedforward control

• Cascade control

• Interlock based on a discrete input

• Input selection when redundant measurements are available

• Flow integration

• Calculations and signal characterization


Example: Single LoopExample: Single LoopExample: Single LoopExample: Single Loop

FC 101

FT 101

Feed

Feed Tank


Single Loop - FieldbusSingle Loop - FieldbusSingle Loop - FieldbusSingle Loop - Fieldbus


Example: Interlock Based on Status of Example: Interlock Based on Status of Blocking ValveBlocking Valve

Example: Interlock Based on Status of Example: Interlock Based on Status of Blocking ValveBlocking Valve

FC 151

FT 151 Reactor 1 Feed

ZT 150


Interlock Example: Use of Discrete Interlock Example: Use of Discrete Input From Upstream On-Off ValveInput From Upstream On-Off ValveInterlock Example: Use of Discrete Interlock Example: Use of Discrete Input From Upstream On-Off ValveInput From Upstream On-Off Valve


Example: Selection of Redundant Example: Selection of Redundant MeasurementMeasurement

Example: Selection of Redundant Example: Selection of Redundant MeasurementMeasurement

Static Mixer

AC 302

AT 301

Reactor 1

Feed A

Feed B

AT 302

AY 302


Automatic Input Selection for Automatic Input Selection for Redundant Measurements Redundant Measurements

Automatic Input Selection for Automatic Input Selection for Redundant Measurements Redundant Measurements


Example: Cascade ControlExample: Cascade ControlExample: Cascade ControlExample: Cascade Control

TC 202

TT 202

TT 201

TC 201

RSP

Reactor 1

Coolant

Discharge


Cascades Loop - FieldbusCascades Loop - FieldbusCascades Loop - FieldbusCascades Loop - Fieldbus


Arithmetic Block May be used to Arithmetic Block May be used to address a Variety of Calculationsaddress a Variety of CalculationsArithmetic Block May be used to Arithmetic Block May be used to address a Variety of Calculationsaddress a Variety of Calculations

• Flow Compensation – Linear

• Flow Compensation – Square root

• Flow Compensation – Approximate

• BTU Flow

• Multiply and Divide

• Average of inputs

• Sum of inputs

• Fourth order polynomial

• Simple HTG compensate level


Example: Calculation and Integration Example: Calculation and Integration of Mass Flowof Mass Flow

Example: Calculation and Integration Example: Calculation and Integration of Mass Flowof Mass Flow

FY 3-4

FT 3-4

PT 3-4

TT 3-4

FY 3-4

Process Steam

Pressure & TemperatureCompensation

Totalized Mass Flow


Example: Arithmetic and Integrator Example: Arithmetic and Integrator Function BlocksFunction Blocks

Example: Arithmetic and Integrator Example: Arithmetic and Integrator Function BlocksFunction Blocks


TE 801A

Distillate Receiver

Column

Distillate

Bottoms

Steam

Feed

TE 801B

TE 801C

TE 801D

TE 801E

Fieldbus enables Multi-sensor ApplicationsFieldbus enables Multi-sensor ApplicationsFieldbus enables Multi-sensor ApplicationsFieldbus enables Multi-sensor Applications

TT 801

Distillation


Multi-sensor Applications (Cont)Multi-sensor Applications (Cont)Multi-sensor Applications (Cont)Multi-sensor Applications (Cont)

• Chemical Reactors

Cooling Fluid In

Cooling Fluid Out

TE 901A-H

TT 901

Process Out

Process In


Example: Multiple Analog Input BlockExample: Multiple Analog Input BlockExample: Multiple Analog Input BlockExample: Multiple Analog Input Block

Supports a Supports a Maximum of 8 Inputs Maximum of 8 Inputs From a Fieldbus From a Fieldbus DeviceDevice


Other Function Blocks Are Defined by Other Function Blocks Are Defined by FF and Supported by Some DevicesFF and Supported by Some Devices

Other Function Blocks Are Defined by Other Function Blocks Are Defined by FF and Supported by Some DevicesFF and Supported by Some Devices

Blocks not included in device testing/registration ITK v4.5 , v5.0

• DC – Device Control (motor control)• OS – Output Splitter (split range control)• LL – Lead Lag (dynamic compensation of feedforward)• DT – Deadtime (dynamic compensation of feedforward)• SPG – Setpoint Ramp Generator (Program setpoint change)• AAL – Analog Alarm (alarming based on calculated value)• CS– Control Selector (override control for constraint handling)• B/G – Bias Gain (coordination of multiple loops)• RA – Ratio (blending to specified feed ratio)


Control Performance Using FieldbusControl Performance Using FieldbusControl Performance Using FieldbusControl Performance Using Fieldbus

The control performance that may be achieved is dependent on many factors:

• Function block execution, maximum response time for compel data and slot time ( dependent of the device technology/design – specific to manufacturer)

• Whether control is done in the field or in the control system (customer decision)

• Scheduling of block execution and communications on the FF segment (dependent of control system design)


AI Function Block Execution TimeAI Function Block Execution TimeAI Function Block Execution TimeAI Function Block Execution Time

AI Function Block Execution Time (Based on 22 manufacturers)

0-50msec

51-100msec

101-150msec

151-200msec


AO Function Block Execution TimeAO Function Block Execution TimeAO Function Block Execution TimeAO Function Block Execution Time

AO Function Block Execution Time (Based on 13 manufacturers)

0-50msec

51-100msec

101-150msec

151-200msec


PID Function Block Execution TimePID Function Block Execution TimePID Function Block Execution TimePID Function Block Execution Time

PID Function Block Execution Time (Based on 16 manufacturers)

0-50msec

51-100msec

101-150msec

151-200msec


DI Function Block Execution TimeDI Function Block Execution TimeDI Function Block Execution TimeDI Function Block Execution Time

DI Function Block Execution Time (Based on 9 Manufacturers)

0-25msec

26-50msec

51-75msec

76-100msec

101-125msec


DO Function Block Execution TimeDO Function Block Execution TimeDO Function Block Execution TimeDO Function Block Execution Time

DO Function Block Execution Time (Based on 10 Manufacturers)

0-25msec

26-50msec

51-75msec

76-100msec

101-125msec


Calculation Block Execution TimesCalculation Block Execution TimesCalculation Block Execution TimesCalculation Block Execution Times

Execution Time of Blocks Used in Calculations

0 0.5 1 1.5 2 2.5

0-25msec

51-75msec

101-125msec

Number of Manufacturers

CHAR

ARITH

INTG

ISEL


Third Generation Devices Offer Significant Third Generation Devices Offer Significant Improvement if Block Execution TimeImprovement if Block Execution Time

Third Generation Devices Offer Significant Third Generation Devices Offer Significant Improvement if Block Execution TimeImprovement if Block Execution Time

Example*:

Second Generation Third Generation Improvement

AI = 30ms AI = 20ms 33%

PID = 45ms PID = 25ms 44%

* Execution times based on Rosemount 3051


Variation in Device Response Time of Variation in Device Response Time of Different Fieldbus DevicesDifferent Fieldbus Devices

Variation in Device Response Time of Variation in Device Response Time of Different Fieldbus DevicesDifferent Fieldbus Devices

Maximum Response Delay Time (Based on 29 Manufacturers)

0-5msec

6-10msec

11-15msec

16-20msec


Typical Slot Time for Different DevicesTypical Slot Time for Different DevicesTypical Slot Time for Different DevicesTypical Slot Time for Different Devices

Slot Time (Based on 29 Manufacturers)

<1.1msec

1.1-1.5msec

1.6-2.1msec


Control Execution is Scheduled Control Execution is Scheduled Based on the Segment MacrocycleBased on the Segment Macrocycle

Control Execution is Scheduled Control Execution is Scheduled Based on the Segment MacrocycleBased on the Segment Macrocycle

A Macrocycle is determined by:

- Function Block Execution times.- Transmission time of the cyclic messages.

-Gaps between messages determined by the Network parameters.

-Time reserved for acyclic messages


MacrocycleMacrocycleMacrocycleMacrocycle

• Function Block execution time depends on the type of block and on the hardware and software design.

• In the time calculation, only blocks that must be executed consecutively are considered.

• Block Execution Time = 30+45+45+80 = 200 ms

• *Note that the AI in the flow device is executed in parallel.

Cascade Control Example

AI=30 PID=45

AI=30 PID=45

AO=80

TT

FT

FCV


Scheduled Control ExecutionScheduled Control ExecutionScheduled Control ExecutionScheduled Control Execution

0 250

ms

AI PID AO

CD CDDATA

DATA

Macro Cycle

Macro Cycle Macro CycleMacro CycleMacro Cycle

2.3 ms 5.4 ms

Bus Traffic


MacrocycleMacrocycleMacrocycleMacrocycle

Some manufactures may by default assume conservative constant values for MRD and SLT. The user may change these values.

FB FB

CDDATA

MID

(MRD+2xSLT)

MID

SLT - Slot timeMRD - Maximum Response DelayMID - Minimum Inter PDU Delay

DATADATA


Network ParametersNetwork ParametersNetwork ParametersNetwork Parameters

• Network Parameters establish how the network operates.

• The LAS must be set with the larger parameter values of the devices participating in the Network.

SLT = 10MRD= 3MID = 12




LAS BackupLAS

LinkSettings

104

12


Impact of Network Parameters on Maximum Impact of Network Parameters on Maximum Number of Communications/SecondNumber of Communications/Second

Impact of Network Parameters on Maximum Impact of Network Parameters on Maximum Number of Communications/SecondNumber of Communications/Second

8 ms

DATACD CD

2.3 41 5.4 3.1

49.50ms

20 / sIdeal Max.SLT= 16

MRD=10MID= 12

DATACD CD

2.3 6.14 5.4 3.1

58 / s

Ideal Max.SLT= 8MRD=3MID=12

17 ms

DATACD CD

2.3 5.4

SLT= 1MRD=1MID= 1

125 / sIdeal Max.


Minimum Execution Time With Only Minimum Execution Time With Only One(1) Control Loop on an H1 SegmentOne(1) Control Loop on an H1 Segment

Minimum Execution Time With Only Minimum Execution Time With Only One(1) Control Loop on an H1 SegmentOne(1) Control Loop on an H1 Segment

AI PID XFR XFRAO

20ms 25ms 30ms 60ms 30ms

Macrocycle = 165 ms

Assumptions: 3rd Generation Transmitter, AI&PID executed in Transmitter, Second generation Valve executes AO


Executing PID in the Valve Reduces the Number of Executing PID in the Valve Reduces the Number of Communications But Increases Loop Execution TimeCommunications But Increases Loop Execution Time

Executing PID in the Valve Reduces the Number of Executing PID in the Valve Reduces the Number of Communications But Increases Loop Execution TimeCommunications But Increases Loop Execution Time

AI XFR PID

20ms 30ms 120ms 60ms

Macrocycle = 230 ms

Assumptions: 3rd Generation Transmitter, AI executed in Transmitter, Second generation Valve executes AO&PID

AO


Minimum Execution Time With Only Two(2) Minimum Execution Time With Only Two(2) Control Loop on an H1 SegmentControl Loop on an H1 Segment

Minimum Execution Time With Only Two(2) Minimum Execution Time With Only Two(2) Control Loop on an H1 SegmentControl Loop on an H1 Segment

AI PID XFR XFRAO

20ms 25ms 30ms 30ms 60ms 30ms 55ms

Macrocycle = 250 ms

Assumptions: 3rd Generation Transmitter, AI&PID executed in Transmitter, Second generation Valve executes AO, 50ms for every 125ms of the execution schedule (for display update)

AI PID XFR XFRAO

ACYCLIC


Impact of Splitting Control Between Impact of Splitting Control Between Fieldbus and Control SystemFieldbus and Control System

Impact of Splitting Control Between Impact of Splitting Control Between Fieldbus and Control SystemFieldbus and Control System

• Execution in the control system is typically not synchronized with function block execution on fieldbus segments.

• Lack of synchronization introduces a variable delay into the control loop as great as the segment macrocycle e.g. 1/2 sec loop may have up to 1/2 sec variable delay.

• Added delay will increase variability in the control loop.


PID executed in the Control System PID executed in the Control System PID executed in the Control System PID executed in the Control System

0 250

AI AO

CD CDDATA

DATA0 250

PID

Minimum Delay

Max Delay

Macrocycle

0 250

PID

0 250

AI AO

CD CDDATA

DATA

Macrocycle

0 250

PID

0 250

PID


Recommendation on Splitting Control Recommendation on Splitting Control Between Fieldbus and Control SystemBetween Fieldbus and Control SystemRecommendation on Splitting Control Recommendation on Splitting Control Between Fieldbus and Control SystemBetween Fieldbus and Control System

• Oversampling of the fieldbus measurement to compensate for lack of synchronization i.e. setting macrocycle faster than control execution is often not practical if the loop execution is fast

• Conclusion: Execute control loops in Fieldbus for better performance.

• If target execution is ½ sec or faster, then limit the number of control loops to no more than two(2) per segment.


Execution of Function Block in H1 CardExecution of Function Block in H1 CardExecution of Function Block in H1 CardExecution of Function Block in H1 Card

• Capability is targeted of v9.x release of DeltaV

• Will allow synchronization of block execution on the H1 card with those on the segment i.e. the H1 card acts as a FF device with function blocks.

• Block execution time on H1 cards is significantly less and will allow a shorter macrocycle or more to be done within a given macrocycle.


Auto-Assigned Execution to H1 Auto-Assigned Execution to H1 – Module Property– Module Property

Auto-Assigned Execution to H1 Auto-Assigned Execution to H1 – Module Property– Module Property


PID Execution in The ControllerPID Execution in The ControllerPID Execution in The ControllerPID Execution in The Controller


PID Assigned to Execute in H1 CardPID Assigned to Execute in H1 CardPID Assigned to Execute in H1 CardPID Assigned to Execute in H1 Card


PID Assigned to Execute in the DevicePID Assigned to Execute in the DevicePID Assigned to Execute in the DevicePID Assigned to Execute in the Device


Viewing Execution ScheduleViewing Execution ScheduleViewing Execution ScheduleViewing Execution Schedule


Schedule – PID in ControllerSchedule – PID in ControllerSchedule – PID in ControllerSchedule – PID in Controller


Schedule – PID in H1 CardSchedule – PID in H1 CardSchedule – PID in H1 CardSchedule – PID in H1 Card

Parameter show when cursor is over item


Schedule – PID in FF TransmitterSchedule – PID in FF TransmitterSchedule – PID in FF TransmitterSchedule – PID in FF Transmitter


Schedule – Showing Execution Divided Schedule – Showing Execution Divided Between Controller, H1 and FF DeviceBetween Controller, H1 and FF Device

Schedule – Showing Execution Divided Schedule – Showing Execution Divided Between Controller, H1 and FF DeviceBetween Controller, H1 and FF Device


SummarySummarySummarySummary

• A variety of control applications may be implemented using the function block capability of FF devices.

• The performance of fast process control loops may be influenced by block execution times and number of loops implemented on a segment.

• Control may be split between the DeltaV Control and FF devices for slower processes.

• Future DeltaV releases are targeted to support assignment of function blocks to execute in the H1 card. This new capability will allow a variety of applications to be addressed with no impact on control performance.

• Please direct questions or comments on this presentation to Terry Blevins ([email protected]) or Marcos Peluso ( [email protected] ).


Where To Get More InformationWhere To Get More InformationWhere To Get More InformationWhere To Get More Information• “Reliability and Performance of Fieldbus installations (Tutorial)”,

Marcos Peluso, Terry Blevins, ISA2002.

• “Application of High Speed Ethernet With Fieldbus Foundation Devices (Tutorial)”, Marcos Peluso, Terry Blevins, ISA2001

• “Advanced Functionality and Diagnostics of Fieldbus Devices (Tutorial)”, Marcos Peluso, Terry Blevins, ISA2000

• “Rules of thumb for applying Fieldbus (Tutorial)”, Marcos Peluso, Terry Blevins, ISA1999.

• “Installation and Checkout of Foundation Fieldbus Installations (Tutorial)”, Marcos Peluso, Terry Blevins, Jim Cameron, Duane Toavs, ISA1998.

• “Planning and Engineering Design for Foundation Fieldbus Installations (Tutorial)”, Marcos Peluso, Terry Blevins, ISA1997

• “Application Solutions Using Fieldbus Devices (Tutorial)”’ Marcos Peluso, Terry Blevins, ISA1996.

• “How Fieldbus May Influence Your Next Project (Tutorial)”, Marcos Peluso, Terry Blevins, Tom Kinney, ISA1995.

achieving target control performance using fieldbus devices achieving target control performance...

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