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FieldBus, the wave of the future

FieldBus, the wave of the future. But I do not recommend it for every system. It should not be used for systems with less than 100 control loops. PC-ControLAB. The primary reason that the field bus was develop was to save construction cost of wiring individual field devices

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FieldBus, the wave of the future

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  1. FieldBus, the wave of the future But I do not recommend it for every system. It should not be used for systems with less than 100 control loops PC-ControLAB The primary reason that the field bus was develop was to save construction cost of wiring individual field devices back to I/O Cabinets that were used in the early Days of the DCS and PLC. However, it turned out that the construction costs were offset by the increase in engineering Presentation by Clifford T. Johnson, PE, Control Systems Engineer Fieldbus Fieldbus ELC-213

  2. Assignment & Lab • FieldBus, the wave of the future • PC-ControLab: Tuning demo not Today Assignment & Lab ELC-213

  3. AS-i (Actuator Sensor Interface) AS-i is the easiest network to install ASi Bus ELC-213

  4. AS-i is simply 2 wires AS-i primarily operates On-Off ball valves that incorporate a rotary valve monitor that is addressed using 5 position dip switch ASi IS Easiest to install ELC-213

  5. AS-i Network Highlights Technology Developer AS-i Consortium Introduced 1993 Openness Multiple vendors, 800+ products, 150 Vendors Type of Network Sensor Bus Physical Media 2-wire cable (flat or round) Network Topology Bus, Ring, Tree, Star Maximum Devices - v2.0 31 nodes (or 248 I/O points) - v2.1 62 nodes (or 434 I/O points) - Maximum Distance 100 meters - Maximum Distance with repeaters 300 meters (max. of 2 repeaters can be used) AS-i is the easiest network to install ASi Highlights ELC-213

  6. Fieldbus provides two-way, multi-drop digital communication between devices on the plant floor as well as the automation and display systems. Thus, FFB is essentially a Local Area Network (LAN) for field devices. Foundation Fieldbus Technology (FFB) Fieldbus Process Plant P Automation and Display Systems L F Foundation Fieldbus-USA ELC-213

  7. Office Automation • Mainframes • Management • Automation & Display Systems • DCS’s, PLC’s, PC’s • SCADA, Supervisory Systems • Instrumentation & Control • Transmitters, Controllers • Valves & Actuators FFB Plant Network Hierarchy Plant Network Local Area Network Fieldbus Network FFB is the only Fieldbus that provides power to the devices and that makes it very difficult to design & Install Foundation Hardest to install ELC-213

  8. SIEMENS SIEMENS ET200C ET200C R Star Bus Line Ring RS 485 FO IEC 1158-2 ProFiBusProcess Field Bus ProFiBus Best overall ELC-213

  9. DeviceNET DeviceNET By Allen-Bradley ELC-213

  10. Allen-Bradley Developed DeviceNET DeviceNET For motor controls ELC-213

  11. What is Ethernet? • The IEEE recognizes Ethernet as standard IEEE802.3 • Defines layers 1 & 2 • Layer 1 defines cables, connectors & electrical characteristics • Layer 2 defines frame format, error checking, and physical addressing (MAC – Medium Access Control) • The technology that Ethernet uses to determine when nodes can transmit is Carrier Sense, Multiple Access, with Collision Detection or CSMA/CD Application 7 Presentation 6 Session 5 Transport 4 Network 3 Data Link 2 Physical 1 Ethernet Not for process control ELC-213

  12. How does CSMA/CD work? • Carrier Sense, Multiple Access, with Collision Detection (CSMA/CD) is a contention based access method: • Carrier Sense: listen before sending • Multiple Access: any device can send data if it doesn’t detect a “busy” signal. • CSMA is analogous to many speaker phones where only one person can talk at a time • Collision Detection senses when two nodes attempt to transmit simultaneously • When a collision is detected, both nodes stop and wait a different, specified, period of time before retrying • This is the underlying reason that Ethernet is termed non-deterministic Average and Standard Deviation determined by network loading Std. Dev. _ X Transmission speed (msec) Ethernet Non Deterministic ELC-213

  13. Ethernet – Myth vs. Reality? • Myth: Non-determinism: Any Ethernet network loaded above 40% will experience an exponential growth in transmission delay times and become non-operational. • Reality: Ethernet delays are linear and can be consistently maintained under 2 ms for a lightly loaded network and 30 ms for a heavily loaded network. • These delays are inconsequential for most process control applications and can be minimized by using switches and routers to manage network topology. However, Critical Control & Safety Systems do not use Ethernet because it is Non-deterministic Ethernet Not for safety systems ELC-213

  14. Fieldbus • IEC/ISA SP50 • Fieldbus Foundation • Profibus PA • HART • Devicebus • Device Net • SDS • Profibus DP • LONWorks • INTERBUS-S • Sensorbus • Seriplex • ASI • INTERBUSLoop Fieldbus Types Hardest Type of Control Best Overall Process Control Logic Control Type of Devices Easiest Low-end bit High-end block Midrange byte Simple Devices Complex Devices Summary FieldBUS Types ELC-213

  15. PC-ControLAB PC-ControLAB is a active demonstration of a control Station that allows you to "TUNE" a simulated controller and view the results. you will download from resources the instructions for tuning a flow, Temperature and Pressure loop for optimum controls, then enter the tuning parameters on an email to me as FLOW: Gain= XX; Reset= XX; (derivative is not used) then the same for PRESS & TEMP Demo PC_ControLAB ELC-213

  16. PC-ControLAB • User-friendly interface resembles a control station.   • Auto/Manual mode selection buttons and indication • Set point and output entry via "jog" buttons or move Pointer • Tuning permits entry of Proportional Band in % and Reset in repeats/min. • Load control buttons permit forcing a step change or enabling automatic load changes. • You should simulate a load change by simply changing the set point  Demo PC_ControLAB ELC-213

  17. PC-ControLAB • Control menu permits selection of control strategies: • Feedback • Override (Selector) • Dual Feedback • Two forms of Feedforward • Ratio • Two forms of Decoupling • Cascade • Four forms of Model-Based Control Demo PC_ControLAB ELC-213

  18. PC-ControLAB Demo PC_ControLAB ELC-213

  19. Homework ASSIGNMENT Web Link Find a site of a Pressure Transmitter that works on Foundation Fieldbus. email web page LINK only to me by Sunday All Emails Subjects and File names must have Subject:Yourlast Name-Subject-AssignmentDate (AD) Email Ex: Johnson-Fieldbus PT-AD Lab: Johnson-PC_ControLab-AD You will lose 1-3 points for incorrect subject Subjects Assignment ELC-213

  20. The End Almost Done The End Instrumentation ELC-213

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