“...dedicated to a single international fieldbus.” © 2003 Fieldbus Foundation 1 Who’s Afraid of Control in the Field? Presented by Andreas Agostin, Pepperl+Fuchs.

“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation

1

Who’s Afraid of Control in the Field?

Presented by

Andreas Agostin, Pepperl+Fuchs Pte Ltd Singapore

On behalf of theFieldbus Foundation Marketing Society Singapore

Slides provides by Endress+Hauser Singapore


2

Who’s Afraid of Control in the Field?

There are concerns about: Using fieldbus Putting instruments in control of the plant Doing something new

These must be addressed.


3

Back to the Future

1950

Single loop contro ller

Process com puter DCS

F ie ldbus

1960 1975 1990 2003


4

Back to the Future

Control in the field is not new: Pneumatics put it there Computers moved it to the control room DCS kept the status quo Foundation Fieldbus puts it back to the field

So what’s the problem?


5

Control Hierarchy Mindset

Enterprise Enterprise

Operations

Conventional Control in the Field

Operations

Control

Field

Field Control

RemoteI/O

Linking Device

Fieldbus Fieldbus

4..

.20

mA


6

Control Hierarchy Mindset

Human factors determine attitudes: Control has no preferences where, for what and

when it is used The real concerns are human

This is the way I was taught

I am not going to stick my head out

Better safe than sorry

But progress has always required change and innovation.


7

Hocus Pocus

What I cannot see, I do not understand: I feel at home with 4-20 mA

Why should I change?

It’s hands-on “screwdriver” technology

I’ve heard fieldbus is good, but I’m still unsureI don’t know how to use it

I don’t know how to implement it

I don’t know who can help me

Economic and technical arguments are not enough: potential users want more support and want to see more solutions.


8

Control in the Field

P ID

P ID

P IDA I

3 E x terna l L inks

– Loop In tegrity

+ Loop In tegrity

2 E x terna l L inks 1 E x terna l L ink

A I A IA O A O

A O


9

Control in the Field (CIF)

Control in the field: Uses the power in the instruments Increases loop integrity Is the key to optimized control Puts high demands on system and devices

Standardized function blocks

Function block instantiation

Virtual communication relationships

Multi-variable optimization

When properly done, CIF adds a new dimension and more flexibility to control system design.


10

Horror Scenarios

Everyone has nightmares but users sleep better at night by: Analyzing the risks Carefully considering redundancy Optimizing distribution of function blocks Investing in good system and segment design Training their operators

And it helps to know what happens whenthings do go bump in the night!


11

IS E L

LA S

Horror Scenarios

HeadlessHorseman:HMI

Psycho:Field Controller

Godzilla:Fieldbus Cable

Zombies:FieldDevices


12

Zombies

A device dies and I loose the loop

PIDPIDPV

OUT

1stGood

GoodBad 1stGood

ISELISEL


13

Zombies

Consequence and recovery strategies: Without device redundancy

Loop lost until device replacement

Bad status propagates through loop and to control system

Final (output) elements move to fail-safe

With device redundancy Loop recovers through input selection block intervention

Replacement must offer function blocks used in control loop – these must be identical to those in failed device, otherwise other actions are needed.


14

Godzilla

Something comes along and chews up the cables,I loose the segment

WireWireFault!Fault!

Active Link Active Scheduler

LAS

Redundant PSU

Back-up LAS

PIDPID

PV

OUT

Back-up LAS

ActiveLink Active Scheduler

LAS


15

Godzilla

Consequence and recovery strategies: With power and LAS redundancy

All loops recover except:those with function blocks in the controller those operating across segments

Bad status propagates through lost loops


With power and control redundancyAll loops recover

With no control redundancy, the back-up LAS is best placed in a device that has little to do.


16

Psycho

The controller is taken out, I loose all control

Back-up Controller/LAS

Active Controller/LASBack-up Controller/LAS

Active Controller/LAS


17

Psycho

Consequence and recovery strategies: With power but without controller redundancy

All loops recover except:those with function blocks in the controller those operating across segments

Bad status propagates through lost loops


With controller redundancyAll loops recover

The system must support control redundancy with back-up controllers.


18

Headless Horseman

The HMI goes blind, I have no idea what’s going on!

Back-up HMIActive HMI


19

Headless Horseman

Consequence and recovery strategies: Control is not affected

Everything runs as normal

With redundant HMIBack-up HMI cuts in

If required, manual shut-down procedurescan be built into the control function blocks

The use of standard off-the-shelf Ethernet components means that HMI redundancy is very economical.


20

Where does CIF make sense?

Example of distillation column control

2x

2xField Controller

Field I/O

Heater room

Controlroom

4x

2x

T

T

Ex-barrier

Ex-barrier

2x

4x

T

T

Ex-barrier

Ex-barrier

Two channels

H1 channels

4x

T

T

Ex-barrier

Ex-barrier

T

T

4x

4x

2x

TC

TT

DT PT

Q

O ilH e a te r B o ile r w ith

w a s te so lve n t

D is tilla t io n C o lu m n


21

Where does CIF make sense?

For the example shown because: Several single loop controllers could be replaced The type of control loop was suited to CIF Control in the field was more cost effective than

installing a DCS With the accompanying HMI, the operator had

a better overview as well as better control

For every project the user benefits could differ, but there will always be more when CIF is used, e.g. high degree of loop integrity and process optimization.


22

Simple is Beautiful

Does control in the field have a future? Smaller, faster, cheaper often means more complexity

Control in the field is simple by nature

The issues at the moment concern standardization as well aslack of knowledge and experience

When these are resolved, acceptance will be high

Centralized supervision is losing groundWith thin-clients, operation is going local

Web-based technology is enabling visualization everywhere

It makes sense to move control to the field.


23

Sleep Well at Night!

Thank you!Any Questions?

Please e-mail to:[email protected]@solutions.endress.com

“...dedicated to a single international fieldbus.” © 2003 Fieldbus Foundation 1 Who’s Afraid of Control in the Field? Presented by Andreas Agostin, Pepperl+Fuchs.

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