“...dedicated to a single international fieldbus.” © 2003 fieldbus foundation 1 who’s afraid...
TRANSCRIPT
“...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
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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Back to the Future
1950
Single loop contro ller
Process com puter DCS
F ie ldbus
1960 1975 1990 2003
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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?
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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!
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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IS E L
LA S
Horror Scenarios
HeadlessHorseman:HMI
Psycho:Field Controller
Godzilla:Fieldbus Cable
Zombies:FieldDevices
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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Zombies
A device dies and I loose the loop
PIDPIDPV
OUT
1stGood
GoodBad 1stGood
ISELISEL
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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
Final (output) elements move to fail-safe
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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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Psycho
The controller is taken out, I loose all control
Back-up Controller/LAS
Active Controller/LASBack-up Controller/LAS
Active Controller/LAS
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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
Final (output) elements move to fail-safe
With controller redundancyAll loops recover
The system must support control redundancy with back-up controllers.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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Headless Horseman
The HMI goes blind, I have no idea what’s going on!
Back-up HMIActive HMI
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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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.
“...dedicated to a single international fieldbus.”© 2003 Fieldbus Foundation
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Sleep Well at Night!
Thank you!Any Questions?
Please e-mail to:[email protected]@solutions.endress.com