DeltaV Tune for DeltaV Tune for Fieldbus PIDFieldbus PID

Support in DeltaV v7.2 and v7.3

Implementation Options with FieldbusImplementation Options with FieldbusImplementation Options with FieldbusImplementation Options with Fieldbus

DeltaV allows all elements of the control loop to be assigned to fieldbus

The loop PID may be assigned to the transmitter or the valve.

Portions of the control loop, such as the PID, may be assigned to the DeltaV controller and the remaining functions such as AI and AO done in fieldbus devices.

Where will PID be Assigned??

Control Performance Achieve Using Control Performance Achieve Using FieldbusFieldbusControl Performance Achieve Using Control Performance Achieve Using FieldbusFieldbus

Function block execution, maximum response time for compel data and slot time ( dependent of the device technology/design – specific to manufacturer) - see ISA2002 Fieldbus Tutorial

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

Scheduling of block execution and communications on the FF segment.

Scheduled Control Execution With FieldbusScheduled Control Execution With FieldbusScheduled Control Execution With FieldbusScheduled Control Execution With Fieldbus

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

Minimum Execution Time With Only Minimum Execution Time With Only One(1) Control Loop on an H1 SegmentOne(1) Control Loop on an H1 SegmentMinimum 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 TimeExecuting 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 Minimum Execution Time With Only Two(2) Control Loop on an H1 SegmentTwo(2) Control Loop on an H1 SegmentMinimum Execution Time With Only Minimum Execution Time With Only Two(2) Control Loop on an H1 SegmentTwo(2) Control 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 SystemImpact of Splitting Control Between Impact of Splitting Control Between Fieldbus and Control SystemFieldbus and Control System

DeltaV module execution is 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 of added variable delay when control is split between fieldbus device and the DeltaV controller.

Added delay will impact control loop tuning and result in increase variability in fast 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

Execute control loops in Fieldbus for better performance when the process dynamics are fast e.g. liquid pressure or flow.

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

Original DeltaV Tune CapabilityOriginal DeltaV Tune CapabilityOriginal DeltaV Tune CapabilityOriginal DeltaV Tune Capability

Only supported PID/ Fuzzy Blocks in DeltaV Controller

Dynamics are captured by a (hidden) Autotuner Modifier so no error is introduced by communications delay/jitter.

DeltaV v7.2 Tuning Support for DeltaV v7.2 Tuning Support for all Manufacturer’s FF Devicesall Manufacturer’s FF DevicesDeltaV v7.2 Tuning Support for DeltaV v7.2 Tuning Support for all Manufacturer’s FF Devicesall Manufacturer’s FF Devices

DeltaV Tune appears and operates the same.

The PID mode changing to Man (rather than LO) during the Test phase

Tuning of fast loops may be conservative because of deadtime introduced by fieldbus communications.

Patent pending.

Shadow PID with Autotune Modifier

Launching DeltaV TuneLaunching DeltaV TuneLaunching DeltaV TuneLaunching DeltaV Tune

The DeltaV Tune application may be launched in context by right clicking on the module or fieldbus block

Testing the ProcessTesting the ProcessTesting the ProcessTesting the Process

When “test” is selected, the PID Autotune modifier changes the PID output by the amount specified and captures the process response.

Select Tuning RuleSelect Tuning RuleSelect Tuning RuleSelect Tuning Rule

The default ( “normal” user ) tuning rules be used with fieldbus PID.

The “normal” rules apply to all process dynamics

DeltaV v7.3 Tuning Support DeltaV v7.3 Tuning Support for Emerson Fieldbus Devicesfor Emerson Fieldbus DevicesDeltaV v7.3 Tuning Support DeltaV v7.3 Tuning Support for Emerson Fieldbus Devicesfor Emerson Fieldbus Devices

All new Emerson fieldbus devices will include the Autotune modifier as part of the PID. Initially available on 3244, 3051, 3144

DeltaV Tune looks and operates the same.

No communications delay or jitter in identifed dynamics.

Patent pending

In Emerson fieldbus devices

ConclusionConclusionConclusionConclusion

Tuning of PID in any fieldbus devices is supported in v7.2. Conservative tuning will be obtained for fast loops.

An improved tuning capabilty is provided in v7.3 for Emerson fieldbus devices. Even the fastest loop may be accurately tuned.

DeltaV Tune support of fieldbus devices enables utilizing control in the field. This can lead to reduced control variability for fast process dynamics.