Practical steps to a successful PROFIBUS project - Richard Needham and Xiu Ji

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Introduction to PROFIBUS and associated benefits
Connection options and rules
Other cabling issues : grounding and interference
Design Considerations
Implementation issues
Essential training

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Practical steps to a successful PROFIBUS project - Richard Needham and Xiu Ji

  1. 1. Practical Steps to a Successful PROFIBUS Project Slides by Dr. Xiu Ji - MMU Presentation today by Richard Needham – Hi-Port Controls
  2. 2. Outline of this presentation Presentation objective Introduction to PROFIBUS and associated benefits Connection options and rules Other cabling issues : grounding and interference Design Considerations Implementation issues Essential training Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 2
  3. 3. Introduction to PROFIBUS Fieldbus is widely used in many automation systems. PROFIBUS solutions for Factory Automation (FA) and Process Automation (PA) Applications also involving drives, instruments, servos, robotics, functional safety, redundancy, and explosive environments etc. Extensive diagnostic functions available to operators and maintenance engineers Diagnostic tools available for engineering, commissioning, maintenance, and fault finding Excellent support from PROFIBUS International, regional events and competence and training centres. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 3
  4. 4. More Information More adjustable settings and parameters (e.g. scaling, linearization and calibration). Diagnostic data to inform if measurement is valid. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 4
  5. 5. Extensive Diagnostics Controller SCADA/HMI 1 2 Engineering Station 3 PA Software 2 Analyser Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 5
  6. 6. PROFIBUS Applications Factory automation Process automation Vehicle manufacture Bottling plants Warehousing systems Switchgear Hollow glass production Chemical industry Petrochemical industry Paper and textile industry Foodstuffs Power stations Sewage plants Drive technology Machine tools Packaging machines Pressing plants Paper production Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji 6 Safety applications Vehicle assembly Machine tool building Slide 6
  7. 7. The PROFIBUS Family PROFIBUS DP (Decentralised Periphery) Low cost, simple, fast for general automation applications Within short distances, in large quantities, mainly in-door, in dry areas, in cabinets Parameters, options and capabilities can be defined using a simple, text ‘GSD’ file. Physical layer uses RS485 or fiber optic Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 7
  8. 8. The PROFIBUS Family PROFIBUS PA (Process Automation) Developed specifically for the process industry to replace 4-20mA transmission Two-wire connection carrying both power and data Spread over long distances, in low quantities, mainly out-doors, in wet and exposed sites Parameters, options and capabilities are defined in additional to a GSD file, in EDD or FDT/DTM Large number of parameters, options and diagnostic events Cyclic and acyclic communications PA equipment is often used in explosive environments Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 8
  9. 9. Transmission Technologies PROFIBUS supports different transmission technologies HART on PROFIBUS LabAutomation XY Weighing & Dosage PROFIsafe, I&M, iPar-Server, Time Stamp, Redundancy, … Communication Technology Transmission Technologies .... PROFIBUS DP (DP-V0, -V1, -V2) Wired Optical RS4 85 / RS485-IS MBP / M BP-IS Engineering Technologies GS D, EDD, FDT / DTM, TCI Common Application Profiles Encoder Ident Systems PA Devices Specific Application Profiles PRO FIdrive Wired, Optical, and Wireless Glass, PC F, Plastic Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Wireless Slide 9
  10. 10. Connection technologies 1 0 PROFIBUS DP uses 2-core shielded and twisted RS485 wiring. 9-pin sub-D or M12 connectors extensively used. DP can also use plastic or glass fibre optic cabling. ST/BFOC connectors widely used PROFIBUS PA uses “Manchester Bus Powered” (MBP) cabling over 2 cores. Glanded screw or M12 connection normally used Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 10
  11. 11. Optical transmission The implementation of a fibre optic cable network involves the use of electro optical converters (OBT and OLM): for long distance, between buildings, and to solve grounding problem (grounds with un-even earth potential). OLM (Optical Link Module) OBT (Optical Bus Terminal) FO Coupler FO Coupler Fibre to Copper Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 11
  12. 12. Control System Architecture Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 12
  13. 13. From DP (RS485) to PA (MBP) 1 1 1 4 To 7 volts 0 0 PROFIBUS PA, MBP PROFIBUS DP, RS485 Current/mA 0 1 1 0 0 +9mA 10 mA -9mA time Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 13
  14. 14. DP & PA Segments One PROFIBUS network can host up to 126 stations (masters and slaves) – capacity of a PROFIBUS DP master Limitation of RS485 and MBP – 32 loads and total cable length per segment Segment 1 RS485 M Repeater S Segment 2 RS485 S Segment 3 Fibre Optic S S R S O S C DP/PA Coupler S S O S S Segment 4 RS485 S M Fibre optic links S Each RS485 segment are best laid out as a “linear bus” daisy-chaining from device to device. Segment 5 MBP MBP segments can be laid out in a more flexible manner using Tee junctions to create spur lines. S Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 14
  15. 15. DP Segment Cable Length When using best quality PROFIBUS RS485 (Type-A) cables, the segment cable length is limited according to the network speed. Baud rate Maximum segment length 9.6 kbit/s 1 200m 19.2 kbit/s 1 200m 45.45 kbit/s 1 200m 93.75 kbit/s 1 200m 187.5 kbit/s 1 000m 500.0 kbit/s 400m 1.5 Mbit/s 200m 3.0 Mbit/s 100m 6.0 Mbit/s 100m 12.0 Mbit/s 100m Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Low speeds Middle speeds High speeds Slide 15
  16. 16. PA Segment Cable Length PA baud rate is fixed at 31.25 kbit/s. The maximum segment cable length is 1900 meters for nonintrinsically safe applications, and…. 1000 meters for intrinsically safe applications Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 16
  17. 17. Segmentation, PA The maximum number of devices on a PA segment is the same as the maximum on a DP segment, which is 32. However, how many slaves can be connected to a PA segment depends primarily on the power supplied to the segment. Segment Coupler V = 13.4 VDC, I = 100 mA Maximum number of PA slaves = 100 / 14 = 7 I actual = 5 x 14 = 70 mA 14 mA 14 mA 14 mA #13 14 mA 14 mA #16 T #17 #15 #14 Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 17
  18. 18. Reflections When electrical signals travel down a cable, any electrical discontinuity can cause reflections to occur The end of the cable in particular is a major discontinuity, which can cause severe reflections, particularly with fast changes Just like an echo, the reflected signal can cause multiple signals or corrupted telegrams to appear on the line Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 18
  19. 19. Reflections Reflection caused by missing terminator Reflection caused by missing terminator Reflection caused by missing terminator Analysis of PROFIBUS system behaviour is covered in “PROFIBUS in Practice – system engineering, troubleshooting and maintenance”. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 19
  20. 20. Termination - Rules To avoid reflections from ends of the cable it is essential that each segment is terminated at both ends and nowhere else Both terminators in each segment must be powered at all times Terminator switches and resisters are normally include in 9-pin PROFIBUS connectors for this purpose, with plug-in terminators used for M12 schemes +5 volt power is needed for these terminators to work properly. This is normally supplied from the connected device Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 20
  21. 21. Termination Standalone termination boxes are also available for DP and for PA Termination on Repeaters Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 21
  22. 22. Termination #10 #0 #1 #11 T T DP/PA coupler Power supply for PA segment T T 1 network with 2 segments. #13 #15 #14 Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji #16 #17 Slide 22
  23. 23. Causes of Reflections Missing terminator Un-powered terminator Terminator switch - faulty Extra terminator Reflection can also be caused by: Un-certified devices Cable length between two devices is too short Spurs are used in high speed networks Wrong types of cables are used Cores are sharply bent Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 23
  24. 24. Allowance of RS485 Spurs Bit rate Total allowable spur capacitance Total Spur cable length/segment* >1.5 Mbit/s None None 1.5 Mbit/s 0.2 nF One spur @ 6.7m or 6.7 m 500 kbit/s 0.6 nF 6 spurs @ 1.1m each 20 m 187.5 kbit/s 1.0 nF 33 m 93.75 kbit/s 3.0 nF 100 m 19.2 kbit/s 15 nF 500 m It is much more flexible @ low speed. * Calculated for PROFIBUS cable type A at 30pF/m Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 24
  25. 25. Allowance of MBP Spurs The length of the individual spur-lines on a PA segment depends upon the total number of spurs used: Number of spur-lines Maximum spur length non-intrinsically safe Maximum spur length intrinsically safe 25 to 32 1m 1m 19 to 24 30 m 30 m 15 to 18 60 m 60 m 13 to 14 90 m 60 m 1 to 12 120 m 60 m Note that the maximum cable length of 1900m includes cable used for spurs. E.g. 18 x 60 = 1080m spurs + 810m trunk line. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 25
  26. 26. Interference 2 6 Interference is picked up from adjacent equipment or connected equipment with poor Electromagnetic Compatibility (EMC) rating. Interference can be caused by: Inadequate earthing of equipment, Poor or incorrect earthing of cable shield, Insufficient segregation of power and bus cables, Routing cables through electrically noisy areas, and Heavy earth currents on the cable screen. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 26
  27. 27. Equipotential Bonding Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 27
  28. 28. Installation: Shielding and Grounding intern 2 8 Shielding and Grounding The recommended grounding practices: Connect all PROFIBUS interfaces and cable shields to ground. Use a grounding cable to go from cabinet to cabinet in the same segment – equipotential bonding. Types of grounding: Direct grounding (at any connecting point) Capacitive grounding Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 28
  29. 29. Equipotential Bonding at a Device Connect the PROFIBUS cable shield to the equipotential bonding at every PROFIBUS station assuming local potentials are equal! Connector Shielded, twisted-pair cable Red = + Green = Rx Cable shield route to ground Rx Tx Tx Device Device Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 29
  30. 30. Connector wiring problems Which connectors are incorrectly wired? A B C Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji D Slide 30
  31. 31. Cable Segregation • All channels and partitions must be properly earthed. • Use flexible bonding links are protected against corrosion. • Braided straps are better than solid metal. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 31
  32. 32. Cable Segregation Distance In general, the greater the spacing between the cables and the shorter the paths run parallel, the lower the risks of interference. Recommended cable segregation distances: 20 cm Cable Category I 50 cm 10 cm Cable Category II 10 cm Cable Category III 50 cm Cable Category IV Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji 50 cm Slide 32
  33. 33. Cable Segregation ? An example: variable frequency drives Can you spot the error here? Power cable route Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 33
  34. 34. Spot the errors Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 34
  35. 35. Spot the errors Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 35
  36. 36. Spot the errors Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 36
  37. 37. Standard connections – PROFIBUS DP Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji 3 7 Slide 37
  38. 38. Standard connections – PROFIBUS PA 3 8 Trunk PROFIBUS DP Link/ Coupler T T PROFIBUS PA Spur lines Devices PROFIBUS DP Link/ Coupler T Junction Box PROFIBUS PA Junction Box Trunk T Spur lines Devices Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 38
  39. 39. Spot the errors Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 39
  40. 40. Design considerations - details Limitations of segment loads and total cable length Standalone terminations for DP, redundant power supply to terminators Network drawings – node addresses, mark of termination position, cable routes, cable length between connectors and junction boxes, trunk cable and drop cable length Piggyback connectors – spare connection into EVERY segment for voltage measurements and troubleshooting Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 40
  41. 41. Design considerations - architecture 4 1 Which network to use – PROFIBUS, PROFINET, DP, PA, AS-i? Designation of safe and hazardous areas Production and functional safety systems Cable routes – fibres, copper cables, earthing systems, equipotential bonding cable in place? Cabinet or field assembly Connection of devices via remote IO or integrated fieldbus? Use of redundancy at difference levels Network and device access for engineering, monitoring and maintenance Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 41
  42. 42. Installation Checklists 4 2 Checklist to determine network topology and obtain the network drawing Checklist for PROFIBUS DP (RS485) Grounding Checklist for PROFIBUS PA (MBP) Grounding Checklist for PROFIBUS DP (RS485) Cabling All above are included in “PROFIBUS in Practice – installing PROFIBUS devices and cables” as templates for a Factory Acceptance Test document. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 42
  43. 43. Practical steps to a successful PROFIBUS project 4 3 The very first step to a successful project should be Training PROFIBUS training courses are available for: Installers, System Designers, Commissioning Engineers, and Maintenance staff. Many industry sectors specify that their staff, contractors and sub contractors must be appropriately trained. Competence Centre - Manchester Metropolitan University Training Centre – Verwer Training and Consultancy Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 43
  44. 44. Certified PROFIBUS Installer Training 4 4 This training is widely accepted as the minimum standard of training for anyone who is working in PROFIBUS systems at a technical level. Available as a one-day training course in house or on-site. It teaches the basic principles of PROFIBUS and covers the basic layout, installation and testing of DP and PA networks. It is also essential basic training for system designers, maintenance and all engineering staff. Background details are covered in the series of “PROFIBUS in Practice”, the orange and blue textbook. Extra days can be added to extend the training for maintenance, design and engineering staff. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 44
  45. 45. PROFIBUS System Design Training 4 5 Good overall design, with good documentation and clear specifications of required wiring, installation, testing, commissioning and final setting-to-work practices are recommended. Production of final ‘as installed’ drawings are also recommended (to assist with subsequent maintenance) Designer training will allow companies to ensure that their designers are aware of the common design pitfalls and able to produce systems that are cost effective, efficient and maintainable. Designer course at MMU is 3 days covering installation, maintenance, and design. Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 45
  46. 46. Summary: Steps to a successfully project 4 6 1. Design staff should be trained before the design starts. 2. Everyone involved in the project at a technical level is trained to an adequate level, at the least to the designer or installer level 3. Make sure that designers are fully aware of the methods for diagnosing and locating faults, before start of design 4. Ensure that health checking and performance monitoring facilities are incorporated into the network 5. Follow the extensive guidance that is available from PI and from competency and training centres, for example, incorporating the checklists in to your installation acceptance tests Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 46

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