Fieldbus Foundation – India Marketing Committee
Changes in Engineering Methodology
Amol Chaubal
Member FFIMC
Honeywell Automation
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Agenda :
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What’s different with FF
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FF Topology
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FF Imp Engineering Aspects
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FF Vs Conventional Implementation
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Summary
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
What changes with FF based system?
4-20mA
fieldbus
P.S.
P.S.
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Analog communication (420ma)
Only PV
Point to Point connectivity
Signal & Power on same or
separate wire
Control loop in DCS Controller
Selectable scan time
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Fully Digital communication
Data/diagnostic/configuration
Multi-drop connectivity
Upto 16/32 devices per
segment
„ Signal & power on same wire
„ Control loop in DCS
controller or on wire
„ Selectable macrocycle
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Typical Conventional Topology
FIELD
Convebtional
Field Instruments
CONTROL/RACK ROOM
Junction
Box
Marshalling
Cabinets
Branch
Cables
Trunk Cables
Junction
Box
24VDC
24VDCBulk
Bulk
Power
Supply
Power Supply
Conventional
Field Instruments
Control System
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Typical Fieldbus Topology
FIELD
Fieldbus-based
Field Instruments
CONTROL/RACK ROOM
Field
Junction
Box
Segment
Segment
Power
Power
Conditioners
Conditioners
Spur
Cables
H1 Trunk
Control System
Field
Junction
Box
24VDC
24VDCBulk
Bulk
Power
Supply
Power Supply
Fieldbus-based
Field Instruments
Fieldbus
Fieldbus Host
Host
Interfaces
Interfaces
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Power Distribution
LH, ρH
= VS
VD1
FD1
ID1(max)
VD1(min)
V
J
VD2
VDn
ID2(max)
FD2
VD2(min)
FDn
IDn(max)
VDn(min)
The number of devices on a fieldbus segment is
limited by ohm’s law:
„
The voltage of the power supply,
„ The resistance of the cable and
„ The amount of current drawn by each device
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Important Engineering considerations with FF
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Segment design – No. of devices & Macrocycle
Close loop distribution – On the wire or in controller
Open loop distribution – Dedicated segments or mixed with
close loops
Future expandability – Spares Philosophy for FIM, devices &
function blocks
Device capabilities – Available blocks, BLAS capability, Block
scan times
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Important Engineering considerations with FF
Segment design :
No. of device
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No. of devices per segment to be limited to 12 (Close+Open)
No. of close loops per segment to be limited to Four
Loops to be segregated into levels depending on their criticality
For critical loops no. of valves per segment to be limited to two
For a Loop the sensing element & valve should reside the same segment
Normally open loops should be implemented on separate segments
Macrocycle design:
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Best possible scan times with control on wire 250 to 300 msec
Configure macro cycle times of 250, 500 & 1000 msec
250 msec – Limit no. of close loops to One
500 msec - Limit no. of close loops to Two
1000 msec - Limit no. of close loops to Four
50% of macro cycle time should be available for unscheduled communications
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Important Engineering considerations with FF
Control on the wire or in controller
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All complex & cascade loops should be implemented in the controller
„ All other loops can be on the wire
„ For a close loop the sensing element and valve should be on the same
segment
Open loop
„
Open loop should be implemented on dedicated segments
„ Macrocycle can be set at one second
„ This allows implementation of 8 to 12 devices per segment
„ Frees up the macro cycle for close loop segments
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Important Engineering considerations with FF
Future expandability – Needs to be defined in terms of
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Addition of H1 Host to the system or controller
„ Addition of devices to an existing segment – Open loop & close loop
„ Addition of new FF function blocks in controller for new devices
„ Addition of function block to an existing device
Spares philosophy – Needs to be defined in terms of
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Installed Spares for FIM or segment
Installed spare for devices (Open or close)
Installed spare for field mega blocks
Spare capacity for no. of VCR’s per segment (Each device requires 5 VCR’s)
Each segment to be loaded to a max of 60% VCR’s
Spare capacity in controller for FF function blocks
Each controller to be loaded to max of 60% FF function blocks
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
FF Vs Conventional – Project Execution
Tools (it’s not a dumb instrument!)
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Bench or Field Configurator
– hardware, software
Physical Layer tester
– simple, but handy
Pre-engineering (FEED)
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More time invested in the beginning will save of lot of time in the end
Be aware of devices, firmware revisions, DD files
Project phases
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Small differences up to the FAT
Time for FAT depends on strategy
Time for SAT depends on strategy
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
FF Vs Conventional - Engineering
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
FF Vs Conventional – Factory Acceptance Test (FAT)
All devices connected
„ additional effort during the FAT to
set up the system
„ reduced time for site commissioning
„ impractical for large systems
Representative number of loops tested
„ each type of device tested
„ make a selection out of the
segments
„ still additional effort during the FAT
„ test loop on wires
No devices connected
„ reduction of time for the FAT
„ increase of time for SAT
„ impractical because of HIGH RISK
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
FF Vs Conventional – Commissioning
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Loop-check will take less time
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Must load everything
regardless of FAT strategy
used
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Saves over-all commissioning
time and facilitates early stratup
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Summary
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Engineering is simple – Powerful tools available
Clear design inputs are mandatory
Design stage is critical & efforts required are more
Saves FAT time
Saves commissioning time
Ease of maintenance
Foundation Fieldbus – Changing the Engineering Field
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation
Changes in Engineering Methodology
Thank You
2008 FFIMC-ISA Vadodara Event
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© 2008 Fieldbus Foundation