Challenges and Lessons Learned for the Design and Implementation of Large PROFIBUS Network

Transcription

1 Challenges and Lessons Learned for the Design and Implementation of Large PROFIBUS Network Standards Certification Education & Training Publishing Conferences & Exhibits Speakers: Francisco Alcalá, PE James Powell, P.Eng 2015 ISA Water / Wastewater and Automatic Controls Symposium August 4-6, 2015 Orlando, Florida, USA

2 Presenter Francisco Alcala, PE, BSEE, Automation Specialist CDM Smith 22 years of experience in Instrumentation and Control design, integration, and maintenance in the water/wastewater, petrochemical, and beverage industries 2

3 Presenter James Powell, P.Eng, Senior Product Specialist, Industrial Communication, Siemens Process Instruments 28 years of experience in Industrial communications systems Co-authored a book on PROFIBUS, called Catching the Process Fieldbus, An Introduction to PROFIBUS for Process Automation 3

4 Agenda Objective PROFIBUS Definition and Types Large Scale Network Evaluation of Network Specification vs. the Projects Requirements PROFIBUS Specification Project Scale and Performance requirement System architecture and Wiring topology uncertainties Change management and Expansion Theoretical Vs real capacity of the network Approach to design iteration Best Practices Conclusion 4

5 Objective Use a case study of a PROFIBUS network of a large plant network. The work will describe the requirements, constrains, and considerations of best practices during the design and construction. A set of milestones will be presented in order to provide a model that could be used in similar projects. 5

6 PROFIBUS Definition and Types PROcess FIeldBUS: Industrial control network that was Introduced in Use a master/slave architecture, specialized "Profiles" and provides services at layers 1, 2 and 7 of the OSI model, although layer 2 also provides some functions of layers 3, 4 and 5. Physical layer 1 can be RS-485, RS-485-IS, MBP or fiber. 6

7 PROFIBUS Definition and Types PLC Cycle time = 10 ms? PROFIBUS Regular Cycle time Cyclic (4 Byte measured value + 1 Byte status DP/PA link PROFIBUS DP up to 12 MBit/s max. 1 ms at 12 MBit/s 20 ms Acyclic (read TAG: 32 Byte) Cycle time = 19.5 ms + (3 x 15.5) ms + 20 ms = 86ms PROFIBUS PA 31,25 KBit/s 19.5 ms 15.5 ms 15.5 ms 15.5 ms Average time per device for the first variable is 15.5 ms time for further variables is 2 ms per variable. 20 ms of overhead 7

8 Large Scale Network A large scale PROFIBUS Network can be determined by the extension of the scope of the project. A simple definition classification of Network scale can be done based on the number of devices. Small scale: 50 < Devices < 150 Medium Scale 150< Devices < 350 Large Scale > 350 Devices A alternative definition of Large Scale network The extension of the scope when the boundaries of the network specification can be exceeded An Detailed Evaluation of Network Specification vs. the Projects Requirements is imperative 8

9 Example: Small network: Univar Chemical Distribution& Storage Toronto 30 storage tanks Application Profibus Commissioning Installation

10 Example: Medium size network: Baker Hughes Specialty Chemical Company 200 points (level, temperature)

11 Example: Large network: Large Polymer Plant Project Wyandotte, MI Main Automation Vendor Responsibilities DCS SIS HIMA MES Integration Instrumentation Operator Training Simulator Commissioning PCS 7 Scope of Supply 5,800 I/O (DCS + SIS) 11 Redundant Controllers 2 Redundant OS Servers 1 Red. Batch Server 9 Client Stations 2 Engineering Stations Project Highlights Largest Profibus installation in North America 3,000 PA Devices in a redundant configuration 300 PA Devices in a nonredundant configuration 500 DP Devices (Simocodes, Micromasters, Scales) 1,000 ET200M Conventional IO

12 Evaluation of the Network Specification PROFIBUS DP Max In/Out Bytes per station: 244 bytes Number of Devices per segment: 32 Number of segment : 10 Number of stations addresses: 126 Segment Length vs Baud Rate (Apply only on Copper) Maximum Amount of repeaters: 9 PROFIBUS PA Fixed baud rate: kbit/s Number of Slave : 31 Number of segment : 10 Number of stations addresses: 126 Power Limitation Segment Cable length Depend of Coupler used 12

13 Evaluation of Requirement and Network Specification Number of station addresses PROFIBUS DP Number of segment : 10 Number of stations addresses: 123 Number of stations after the Y-Link: 64 Maximum data after the Y-Link: 244 bytes Maximum Amount of repeaters: 9 Devices 13 Devices 17 Devices 17 Devices 19 Devices 24 13

14 Evaluation of Requirement and Network Specification PROFIBUS PA Segment Length vs Spurs lines spur Notes: Trunk line must be longer than the longest spur! Tree is worst case situation and is what the chart is based on spur spur trunk spur spur 14

15 PROFIBUS DP Segment Length vs Baud Rate Baud rate (kbaud) Max. Segment Length 9.6 1,200 m ,200 m ,200 m ,200 m ,000 m m 1, m 3, m 6, m 12, m Warnings: One meter rule: Ensure a minimum length of 1 meter between devices Two meter rule: If only one device is on the segment then you will need a minimum of 2 meters between repeater/master and slave 15

16 All bus technology has it s limits 16

17 Evaluation of the Project Requirements (Design Criteria) Just because you can does not mean that you should! 17

18 PROFIBUS Published limits vs real limits Published Limits 5 couplers per link module Maximum number of instruments per DP/PA link module = 64 Real Limits Aim for between 15 to 18 instruments per Link. You can go up to 25 but no more. Typically this means no more than 1 coupler for GP and 3 for IS. (Please note: When you are laying out your wires sometime you will need to lightly load a coupler. In this case you could need more couplers) 18

19 Evaluation of the Project Requirements (Design Criteria for case Study Vitag Biosolids Fertilizer project in Zellwood Florida) Project Scale and Performance requirement 198 PROFIBUS DP DEVICES 3 MCCs 62 VFDs 10 Metering pumps 65 Starters 19 Valve actuators 42 PROFIBUS DP Instruments 10 RIOs Hardwired AI/AO: 17 Hardwired DI/DO : PROFIBUS PA INSTRUMENTS Required Up time % 91 continuous control loops Cyclical communication of more than 1500 I/O points, Acyclic communication of more that 1000 tags to be monitored and configures by Asset Management Software Cycle time < 500 ms for ON/OFF control, < 300 ms for PID control 19

20 Evaluation of the Project Requirements (Design Criteria for case Study Vitag Biosolids Fertilizer project in Zellwood Florida) System Architecture and Wiring topology uncertainties Redundant PROFIBUS DP and PLC Architecture 160 K sf of process area to be networked More that 1500 feet of networked to be wired 10 RIOs 5 Process Areas 2 classified areas Base design on Trunk Topology with close evaluation feasible spur line by RFI. Change management and Expansion Required the addition of new devices with minimum to none operation interruption 20% of actives network spare required 20

21 Evaluation of the Project Requirements (Design Criteria) Approach to design iteration Iteration 1 Definition of major components of the network based on the system architecture Definition of criteria for network segmentation RIO location Devices physical location Devices count Byte Counts Third part evaluation Iteration 2 Revision of network segmentation Cycle time Current limitation Devices count Byte counts Iteration 3 Revision of network flexibility for changes during shop drawing and panel construction New instrumentation Swapping pf PROFIBUS DP and PA devices 21

22 EVALUATION OF THE PROJECT REQUIREMENTS (DESIGN CRITERIA, SYSTEM ARCHITECTURE) 22

23 Evaluation of Requirement and Network Specification Max In/Out Bytes per station: 244 bytes MCC1 Total Devices VFD FVNR RVSS X number of starters with an average of 4 byte used YMCC1 Number Y Linkof1 VFD with an 38 average 15of 12 Byte 23 used Bytesused by Power monitor bytes 4X + 12Y + 40 < 200 bytes X+ Y < 23 PM 0 0 IM Bytes The combination of VFD and Starter that meet the design criteria are 8 and

24 Evaluation of Requirement and Constrains Segment Length vs Baud Rate 24

25 Evaluation of Requirement and Constrains Segment Length vs Baud Rate 25

26 Evaluation of Requirement and Network Specification Segmentation Table RIO Segment MAIN PLC Eroom DP/Y-Link 1 MAIN PLC Eroom DP/Y-Link 2 MAIN PLC Eroom DP/Y-Link 3 MAIN PLC Eroom DP/Y-Link 4 MAIN PLC Eroom DP/Y-Link 5 GPCP RIO1 DP/PA Coupler 3 1/3 2 GPCP RIO2 DP/PA Coupler 3 1/3 2 GPCP RIO2 DP/PA Coupler 3 1 GPCP RIO2 DP/PA Coupler 4 1 GPCP RIO3 DP/PA Coupler Ex(i) 3 1 GPCP RIO3 DP/PA Coupler Ex(i) 3 2 GPCP RIO3 DP/PA Coupler Ex(i) 3 3 GPCP RIO3 DP/PA Coupler Ex(i) 3 4 GPCP RIO3 GPCP RIO4 DP/PA Coupler 5 1 GPCP RIO4 DP/PA Coupler 6 1 GPCP RIO4 DP/PA Coupler 7 1 GPCP RIO5 DP/PA Coupler Ex(i) 3 1/3 5 GPCP RIO5 DP/PA Coupler Ex(i) 4 1/4 3 OCCP_RIO1 DP/PA Coupler Ex(i) 3-1/3-3 OCCP_RIO2 DP/PA Coupler Ex(i) 3-1/ ISA WWAC Symposium Aug 4-6, 2015 Orlando, Florida, USA OCCP_RIO2 DP/PA Coupler Ex(i) 4-1/4-5 Devices Bytes Current Average Scan Consumption Time Second ma Average Byte Weighted Scan Time Second < 100 mts = better than 1.5 KBPS for 244 bytes = 16 ms 15.5 ms per device + 20 ms of overhead time + 1ms plus 2 ms per additional variable. Number of Variables = (byte/5) 26

27 Best Practices Follow all the design rule Be conservative in your design and leave room for surprises Bytes counts are relevant for large networks Accept that design is an iterative process Use a 2nd expert to help out two pairs of eyes! 27

28 Conclusion Detailed Evaluation of Network Specification vs. the Projects Requirements is imperative A conservative approach during the network design to provide flexibility and expansion is not a bad idea. A three tiers iteration process of design including a third part revision is recommendable for large scale networks Follow all the design rule with conservative approach Used the knowledge available 28

29 Questions? 29