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Practical Steps to a SuccessfulPROFIBUS Project
Slides by Dr. Xiu Ji - MMU
Presentation today by Richard Needham – Hi-Port Controls
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 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 explosiveenvironments 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 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 5
Extensive Diagnostics
Controller
EngineeringStation
PA Software
SCADA/HMI
12
23
Analyser
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 6
6PROFIBUS Applications
Vehicle manufactureBottling plantsWarehousing systemsSwitchgearHollow glass production
Vehicle assemblyMachine tool building
Chemical industryPetrochemical industryPaper and textile industryFoodstuffsPower stationsSewage plants
Machine toolsPackaging machinesPressing plantsPaper production
Factoryautomation
Processautomation
Drivetechnology
Safetyapplications
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 8
The PROFIBUS Family
PROFIBUS PA (Process Automation)Developed specifically for the process industry to replace 4-20mA transmissionTwo-wire connection carrying both power and dataSpread over long distances, in low quantities, mainly out-doors, in wet and exposed sitesParameters, options and capabilities are defined in additional to a GSD file, in EDD or FDT/DTMLarge number of parameters, options and diagnostic eventsCyclic and acyclic communicationsPA equipment is often used in explosive environments
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 9
Transmission Technologies
Communication Technology
Transmission Technologies
PROFIBUS DP (DP-V0, -V1, -V2)
Wired RS485 / RS485-IS
MBP / MBP-IS
Engi
neer
ing
Tech
nolo
gies
GS
D, E
DD,
FD
T / D
TM, T
CI
OpticalGlass, PCF, Plastic
Wireless
PRO
FIdr
ive
PA D
evice
s
Enco
der
Iden
t Sys
tem
s
Wei
ghin
g &
Dos
age
HAR
T on
PR
OFI
BUS
LabA
utom
atio
n
SpecificApplication Profiles
CommonApplication Profiles
XY . . . .
PROFIsafe, I&M, iPar-Server, Time Stamp, Redundancy, …
Communication Technology
Transmission Technologies
PROFIBUS DP (DP-V0, -V1, -V2)
Wired RS485 / RS485-IS
MBP / MBP-IS
Engi
neer
ing
Tech
nolo
gies
GS
D, E
DD,
FD
T / D
TM, T
CI
OpticalGlass, PCF, Plastic
Wireless
PRO
FIdr
ive
PA D
evice
s
Enco
der
Iden
t Sys
tem
s
Wei
ghin
g &
Dos
age
HAR
T on
PR
OFI
BUS
LabA
utom
atio
n
SpecificApplication Profiles
CommonApplication Profiles
XY . . . .
PROFIsafe, I&M, iPar-Server, Time Stamp, Redundancy, …
PROFIBUS supports different transmission technologiesWired, Optical, and Wireless
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 10
Connection technologies
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
10
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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, andto solve grounding problem (grounds with un-even earth potential).
Fibre to Copper
OLM (Optical Link Module)OBT (OpticalBus Terminal)
FOCoupler
FOCoupler
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 12
Control System Architecture
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 13
From DP (RS485) to PA (MBP)
0
-9mA
time
Current/mA
+9mA
1 1 0 0
PROFIBUS PA, MBP
10 mA
4To7
volts
PROFIBUS DP, RS485
0 0
1 1 1
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 14
DP & PA Segments
One PROFIBUS network can host up to 126 stations (masters and slaves) –capacity of a PROFIBUS DP masterLimitation of RS485 and MBP – 32 loads and total cable length per segment
M
S
S S
S
S S
S
S
M
S
S
S
SR O O
Segment 1 RS485
Segment 2 RS485
Segment 3 Fibre Optic
Segment 4 RS485
Segment 5 MBP
Repeater
Fibre optic links
C
DP/PA Coupler
SMBP segments can be laid out in a more flexible manner using Tee junctions to create spur lines.
Each RS485 segment are best laid out as a “linear bus” daisy-chaining from device to device.
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 length9.6 kbit/s 1 200m
19.2 kbit/s 1 200m45.45 kbit/s 1 200m93.75 kbit/s 1 200m187.5 kbit/s 1 000m500.0 kbit/s 400m1.5 Mbit/s 200m3.0 Mbit/s 100m6.0 Mbit/s 100m
12.0 Mbit/s 100m
Low speeds
High speeds
Middle speeds
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 16
PA Segment Cable Length
PA baud rate is fixed at 31.25 kbit/s.
The maximum segment cable length is 1900 meters for non-intrinsically safe applications, and….
1000 meters for intrinsically safe applications
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 CouplerV = 13.4 VDC, I = 100 mA
#13 #14#15
#16#17
T
14 mA 14 mA 14 mA 14 mA 14 mA
Maximum number of PA slaves = 100 / 14 = 7
I actual = 5 x 14 = 70 mA
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 19
Reflection caused by missing terminator
Reflection caused by missing terminator
Reflection caused by missing terminator
Reflections
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 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 21
Termination
Standalone termination boxes are also availablefor DPand for PA
Termination on Repeaters
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 22
Termination
1 network with 2 segments.
DP/PA coupler
#1#0 #10 #11
#13 #14#15
#16#17
Power supply for PA segment
TT
T
T
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 23
Causes of Reflections
Missing terminatorUn-powered terminatorTerminator switch - faultyExtra terminatorReflection can also be caused by:
Un-certified devices Cable length between two devices is too shortSpurs are used in high speed networksWrong types of cables are usedCores are sharply bent
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 24
Allowance of RS485 Spurs
Bit rateTotal allowable spur
capacitanceTotal Spur cable length/segment*
>1.5 Mbit/s None None
1.5 Mbit/s 0.2 nF 6.7 m
500 kbit/s 0.6 nF 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
* Calculated for PROFIBUS cable type A at 30pF/m
One spur @ 6.7m or
6 spurs @ 1.1m each
It is much more flexible @ low speed.
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 lengthnon-intrinsically safe
Maximum spur lengthintrinsically safe
25 to 32 1 m 1 m
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 26
Interference
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, andHeavy earth currents on the cable screen.
26
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 27
Equipotential Bonding
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 28
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
Installation: Shielding and Grounding 28
intern
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 29
Equipotential Bonding at a Device
Connect the PROFIBUS cable shield to the equipotential bonding at every PROFIBUS station assuming local potentials are equal!
Shielded, twisted-pair cable
Cable shield route to groundRx
Tx Tx
Rx
Connector
Device Device
Red = +Green = -
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 30
Connector wiring problems
Which connectors are incorrectly wired?
A CB D
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 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:
Cable Category II
20 cm
10 cm 10 cm
50 cm 50 cm 50 cm
Cable Category I
Cable Category III
Cable Category IV
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 34
Spot the errors
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 35
Spot the errors
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 36
Spot the errors
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 37
Standard connections – PROFIBUS DP37
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 38
Standard connections – PROFIBUS PA38
TLink/Coupler
TPROFIBUS DP PROFIBUS PA
Trunk
Spur lines
Devices
Link/Coupler
TPROFIBUS DP PROFIBUS PA TJunction
Box Junction
Box
Spur lines
Trunk
Devices
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 39
Spot the errors
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 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 41
Design considerations - architecture
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
41
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 42
Installation Checklists
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.
42
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 43
Practical steps to a successful PROFIBUS project
The very first step to a successful project should be
TrainingPROFIBUS training courses are available for:
Installers,System Designers,Commissioning Engineers, andMaintenance 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
43
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 44
Certified PROFIBUS Installer Training
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.
44
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 45
PROFIBUS System Design Training
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.
45
Practical steps to a successful project, The PROFIBUS Group Seminars, Dr Xiu Ji Slide 46
Summary: Steps to a successfully project
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
46