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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 - PowerPoint PPT Presentation
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FieldBus, the wave of the futureFieldBus, the wave of the future
Fieldbus ELC-213Fieldbus
Presentation by Clifford T. Johnson, PE, Control Systems Engineer
But I do not recommend it for every system.It should not be used for systems with
less than 100 control loops
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
PC-ControLAB
Today Assignment & Lab ELC-213
Assignment & LabAssignment & Lab•FieldBus, the wave of the future•PC-ControLab: Tuning demo
Bus ELC-213
AS-i (Actuator Sensor Interface)AS-i (Actuator Sensor Interface)
ASi
AS-i is the easiest network to install
IS Easiest to install ELC-213
AS-i is simply 2 wiresAS-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
Highlights ELC-213
AS-i Network HighlightsAS-i Network Highlights
Technology Developer AS-i Consortium Introduced 1993
Openness Multiple vendors, 800+ products, 150 Vendors
Type of Network Sensor BusPhysical Media 2-wire cable (flat or round)
Network Topology Bus, Ring, Tree, StarMaximum 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)
ASi
AS-i is the easiest network to install
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.
Fieldbus
Automation and
Display Systems
P
L
F
Process Plant
Foundation Fieldbus Technology (FFB)
Foundation Fieldbus Technology (FFB)
Foundation Fieldbus-USA ELC-213
Hardest to install ELC-213
FFB Plant Network HierarchyFFB Plant Network Hierarchy
Foundation
PlantNetwork
Office Automation• Mainframes • Management
Local AreaNetwork
Automation & Display Systems• DCS’s, PLC’s, PC’s• SCADA, Supervisory Systems
FieldbusNetwork
Instrumentation & Control• Transmitters, Controllers• Valves & Actuators
FFB is the only Fieldbus that provides power to the devices and that makes it very difficult to design & Install
Best overall ELC-213
ProFiBusProcess Field
Bus
ProFiBusProcess Field
Bus
ProFiBus
SIEMENS
ET200C
SIEMENS
ET200C
Bus
R
Star
Ring
Line
FO
RS 485
IEC 1158-2
DeviceNET ELC-213
Allen-Bradley Developed DeviceNETAllen-Bradley Developed DeviceNET
For motor controls
What is Ethernet?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
Presentation
Session
Transport
Network
Data Link
Physical1
2
3
4
5
6
7
Ethernet ELC-213Not for process control
How does CSMA/CD work?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
Transmission speed(msec)
_X
Average andStandard Deviation
determinedby network loading
Std. Dev.
Ethernet ELC-213Non Deterministic
Ethernet – Myth vs. Reality?
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 ELC-213Not for safety systems
FieldBUS Types ELC-213
Fieldbus TypesFieldbus Types
Summary
Sensorbus
• Seriplex• ASI• INTERBUSLoop
Devicebus
• Device Net• SDS• Profibus DP• LONWorks• INTERBUS-S
Fieldbus
• IEC/ISA SP50• Fieldbus Foundation• Profibus PA• HART
Type ofDevices
Type ofControl
ProcessControl
LogicControl
Low-endbit
Midrangebyte
High-endblock
Simple Devices Complex Devices
Easiest
Hardest
Best Overall
PC_ControLAB ELC-213
PC-ControLABPC-ControLAB
Demo
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
PC_ControLAB ELC-213
PC-ControLABPC-ControLAB
Demo
•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
PC_ControLAB ELC-213
PC-ControLABPC-ControLAB
Demo
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
Assignment ELC-213
Homework ASSIGNMENT Web LinkHomework ASSIGNMENT Web LinkFind a site of a Pressure Transmitter that works on
Foundation Fieldbus. email web page LINK only to me by Sunday
Email Ex:Email Ex: Johnson-Fieldbus PT- Johnson-Fieldbus PT-AD
Lab: Lab: Johnson-PC_ControLab-Johnson-PC_ControLab-AD
All Emails Subjects and File names must haveAll Emails Subjects and File names must have
You will lose 1-3 points for incorrect subject
Subjects
SubjectSubject::Your last Name-Subject-Assignment Date (AD)