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Achieving Target Control Performance Using Fieldbus Devices Achieving Target Control Performance Using Fieldbus Devices.

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Presentation on theme: "Achieving Target Control Performance Using Fieldbus Devices Achieving Target Control Performance Using Fieldbus Devices."— Presentation transcript:

1 Achieving Target Control Performance Using Fieldbus Devices Achieving Target Control Performance Using Fieldbus Devices

2 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 2 Presenters Terry Blevins Marcos Peluso Dan Christensen

3 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 3 IntroductionIntroduction 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

4 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 4 FF 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 Testing, v4.5

5 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 5 Applications that may be addressed using 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

6 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 6 Example: Single Loop FC 101 FT 101 Feed Feed Tank

7 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 7 Single Loop - Fieldbus

8 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 8 Example: Interlock Based on Status of Blocking Valve FC 151 FT 151 Reactor 1 Feed ZT 150

9 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 9 Interlock Example: Use of Discrete Input From Upstream On-Off Valve

10 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 10 Example: Selection of Redundant Measurement Static Mixer AC 302 AT 301 Reactor 1 Feed A Feed B AT 302 AY 302

11 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 11 Automatic Input Selection for Redundant Measurements

12 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 12 Example: Cascade Control TC 202 TT 202 TT 201 TC 201 RSP Reactor 1 Coolant Discharge

13 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 13 Cascades Loop - Fieldbus

14 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 14 Arithmetic Block May be used to address 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

15 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 15 Example: Calculation and Integration of Mass Flow FY 3-4 FT 3-4 PT 3-4 TT 3-4 FY 3-4 Process Steam Pressure & Temperature Compensation Totalized Mass Flow

16 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 16 Example: Arithmetic and Integrator Function Blocks

17 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 17 TE 801A Distillate Receiver Column Distillate Bottoms Steam Feed TE 801B TE 801C TE 801D TE 801E Fieldbus enables Multi-sensor Applications TT 801 Distillation

18 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 18 Multi-sensor Applications (Cont) Chemical Reactors Cooling Fluid In Cooling Fluid Out TE 901 A-H TT 901 Process Out Process In

19 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 19 Example: Multiple Analog Input Block Supports a Maximum of 8 Inputs From a Fieldbus Device

20 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 20 Other Function Blocks Are Defined by FF 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)

21 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 21 Control 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)

22 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 22 AI Function Block Execution Time

23 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 23 AO Function Block Execution Time

24 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 24 PID Function Block Execution Time

25 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 25 DI Function Block Execution Time

26 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 26 DO Function Block Execution Time

27 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 27 Calculation Block Execution Times

28 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 28 Third Generation Devices Offer Significant Improvement if Block Execution Time Example*: Second Generation Third Generation Improvement AI = 30msAI = 20ms 33% PID = 45msPID = 25ms 44% * Execution times based on Rosemount 3051

29 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 29 Variation in Device Response Time of Different Fieldbus Devices

30 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 30 Typical Slot Time for Different Devices

31 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 31 Control Execution is Scheduled Based 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

32 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 32 MacrocycleMacrocycle 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 = = 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

33 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 33 Scheduled Control Execution 0250 ms AIPIDAO CD DAT A Macro Cycle 2.3 ms 5.4 ms Bus Traffic

34 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 34 MacrocycleMacrocycle Some manufactures may by default assume conservative constant values for MRD and SLT. The user may change these values. FB CD DATA MID (MRD+ 2xSLT) MID SLT - Slot time MRD - Maximum Response Delay MID - Minimum Inter PDU Delay DATA

35 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 35 Network 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 = 10 MRD= 3 MID = 12 SLT = 8 MRD= 3 MID = 10 SLT = 4 MRD= 4 MID = 8 SLT = 5 MRD= 4 MID = 8 LAS Backup LAS Link Settings

36 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 36 Impact of Network Parameters on Maximum Number of Communications/Second 8 ms DATACD ms 20 / s Ideal Max. SLT= 16 MRD=10 MID= 12 DATACD / s Ideal Max. SLT= 8 MRD=3 MID=12 17 ms DATACD SLT= 1 MRD=1 MID= / s Ideal Max.

37 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 37 Minimum Execution Time With Only One(1) Control Loop on an H1 Segment AIPIDXFR AO 20ms 25ms 30ms 60ms 30ms Macrocycle = 165 ms Assumptions: 3 rd Generation Transmitter, AI&PID executed in Transmitter, Second generation Valve executes AO

38 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 38 Executing PID in the Valve Reduces the Number of Communications But Increases Loop Execution Time AIXFR PID 20ms 30ms 120ms 60ms Macrocycle = 230 ms Assumptions: 3 rd Generation Transmitter, AI executed in Transmitter, Second generation Valve executes AO&PID AO

39 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 39 Minimum Execution Time With Only Two(2) Control Loop on an H1 Segment AIPIDXFR AO 20ms 25ms 30ms 30ms 60ms 30ms 55ms Macrocycle = 250 ms Assumptions: 3 rd Generation Transmitter, AI&PID executed in Transmitter, Second generation Valve executes AO, 50ms for every 125ms of the execution schedule (for display update) AIPIDXFR AO ACYCLIC

40 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 40 Full loaded segment statistics

41 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 41 Impact of Splitting Control Between Fieldbus 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.

42 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 42 PID executed in the Control System 0250 AIAO CD DAT A 0250 PID Minimum Delay Max Delay Macrocycle 0250 PID 0250 AIAO CD DAT A Macrocycle 0250 PID 0250 PID

43 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 43 Recommendation on Splitting Control Between 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.

44 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 44 Execution 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.

45 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 45 Auto-Assigned Execution to H1 – Module Property

46 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 46 PID Execution in The Controller

47 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 47 PID Assigned to Execute in H1 Card

48 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 48 PID Assigned to Execute in the Device

49 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 49 Viewing Execution Schedule

50 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 50 Schedule – PID in Controller

51 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 51 Schedule – PID in H1 Card Parameter show when cursor is over item

52 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 52 Schedule – PID in FF Transmitter

53 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 53

54 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 54 Schedule – Showing Execution Divided Between Controller, H1 and FF Device

55 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 55 SummarySummary 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 or Marcos Peluso (

56 [File Name or Event] Emerson Confidential 27-Jun-01, Slide 56 Where 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.


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