Introduction to Fieldbus Foundation Physical Layer

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Brandon Potter
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1 Introduction to Fieldbus Foundation Physical Layer Fazi Hashim MTL Muhammad Syafiq bin Hamid KLAESB Product Sales /Application Engineer

2 Fieldbus What is fieldbus Benefits of fieldbus How is fieldbus different to 4-20mA? Wiring and Interconnection Components Topologies (Design) tools Installation and lessons learned Earthing/Grounding Communication 2

3 What is fieldbus (Foundation) Fieldbus: is all-digital, serial communication system interconnects field equipment such as sensors, actuators and controllers is used in both process and manufacturing automation has built-in capability to distribute the control application across the network 3

4 What is fieldbus Foundation Fieldbus connects many instruments on the same segment allows various hazardous area methods on the same segment (e.g. Ex d and Ex i using fieldbus barriers) not done so that plant people do not get confused provides/requires/uses intelligent field instruments regardless their function, whether temperature, ON/OFF valves, flow, pressure, etc. uses standardized device configuration methods DD and EDDL 4

5 Fieldbus Infrastructure Foundation Fieldbus uses a common FF power supply (or FF IS power supply) compared to multiple isolators and individual wiring 5

6 Benefits of fieldbus Some of the many benefits of fieldbus: Faster and easier to design Greater flexibility (adding/changing devices drawings remain unchanged) Reduced validation, particularly for I.S. (e.g. FISCO) Higher accuracy (digital data throughout) Precise timing improved process control Reduced components (less isolators, I/O cards), less wiring, less cabinet space Less prone to failures (real Single Loop Integrity, e.g. with Redundant FISCO) Diagnostics are included, and do not need to be designed-in 6

7 How does it work? ma bps (bit per second) T Device 1 Device 2 Device 3 Average 15.29mA per device base current Constant current + Fieldbus Speed: approx. 25 values per second Loop time for 3 devices: 100ms (e.g.) 42.5 C, everything ok Flow is 0.15 m/s, Temperature is 42.5 C, everything ok 36 mbar, but I need maintenance soon, my diaphragm has built-up time Fieldbus 7

8 Physical layer elements Gen. Purpose Host Computer 24VDC FFPS FFPS T T Power supply / Conditioner Redundant FF Power Supply & Conditioner &Terminator Device Coupler & Terminator T Wiring components H1 Interface (non-is) Trunk (non-is) Spurs Cable Device 1 Device 2 Device 3 8

9 Terminators Required for all balanced transmission lines (= differential signal not referenced to ground, 0V, earth or so) Eliminates reflection (matches cable impedance) A terminator for light reflections 9

10 Physical Layer IEC Physical Layer standard 31.25kbit/s transmission rate Up to 32 devices per segment - depends on several factors Limited to 16 by host Limited to less by distance Limited to less by process cycle time Current best practice is 10+2 spare =12 instruments Shielded twisted pair (type A) recommended can use existing field wiring 2-core-cable carries power and signal (like HART) Up to 1900m (total) with type A cable up to 9.5km with repeaters (normally not used) FISCO IIB: up to 800m trunk practical Fieldbus barrier: up to 1200m trunk practical Up to 120m spur length

11 Physical Layer Point-to-point ( = 1 device only) - not cost efficient Line (bus with spurs) - high maintenance Daisy chain - prone to failures Chickenfoot (tree) - Highest reliability, best practice Line Daisy chain Device connection Can be intrinsically safe Chickenfoot 11

12 Fieldbus Cable Example: Type A cable: Shielded twisted pair Recommended Type A does not specify the diameter; You can get type A cable in AWG 22, AWG 18, AWG 16, etc Type A is also available as multipair: as long as individual pairs are twisted and shielded, it is type A

13 Full range of FF Power supplies Single Segment For solar powered applications Dual Segment / Redundant Multiple segments redundant 8 Segments Redundant, High Density 2x4Segments N+1 Redundant, High Density, Flexible power Redundant FISCO Entity FISCO FNICO 13

14 Device Coupler (Megablock/fieldbus barrier) Non-IS / Zone 2 Zone 1 / Ex me Fieldbus Barrier For advanced High Energy Trunk Zone 1/0 / Ex i Simple & Reliable Solution Redundant Fieldbus Barrier For advanced High Energy Trunk 14

Device Couplers (Megablock/fieldbus barrier) Device couplers

short circuit protection Wiring blocks (not recommended): Connect

Fieldbus barriers: Galvanically isolated device couplers Provide

15 Device Couplers (Megablock/fieldbus barrier) Device couplers (recommended): Connect instruments via spurs Spurs have individual short circuit protection Wiring blocks (not recommended): Connect instruments via spurs Spurs do not have short circuit protection Fieldbus barriers: Galvanically isolated device couplers Provide intrinsically safe (Ex i) spurs Used for High Energy Trunk applications 15

16 Surge on Fieldbus New: FS32 Surge Protector Plug-on solution Easily applied to retrofit existing installations with Megablocks/FBB 16

17 Fieldbus topologies HET (Redundant) FISCO

18 Fieldbus Design Tools (Examples)

19 Project Procedure Best practice: Bench test Functional tests and interoperability test FAT SAT 19

20 Portable diagnostic tools Fieldbus tester FBT-6 Connect at field junction box / FFPS cabinet Measures relevant fieldbus parameters Establishes baseline after commissioning Transfer data to PC via USB Do this regularly for trending data 20

21 Earthing/Grounding Grounding in the control room One point grounding only Continuous shield from control room to the field Shield not connected at the field instrument 21

22 Communication Digital communication e.g C or mbar Diagnostic always included e.g. Good, Uncertain, Bad Block-based: function blocks (AI/AO/DI/DO/PID/ ), transducer blocks (virtualization of the hardware), resource block (device identification) Device can contain multiple function blocks e.g. pressure TX: AI (absolute pressure), AI (diff. pressure), AI (temperature) 22

23 Communication Scheduled communication Time synchronized Deterministic Precisely periodic (isochronous) ( macro cycle ) Leads to higher accuracy in PID control; Designed for process control 23

Fieldbus Foundation TM Physical Design. Joseph Khoo AP Regional Sales Director R.Stahl

Fieldbus Foundation TM Physical Design. Joseph Khoo AP Regional Sales Director R.Stahl Fieldbus Foundation M Physical Design Joseph Khoo AP Regional Sales Director R.Stahl 1 Fieldbus How is fieldbus different to 4-20mA? Wiring and Interconnection Components opologies Design tools Installation