CONTROL SYSTEMS TYPES1) PLC
2) DCS
3) PC- Based Controls.
PLC • Sequentional logic solver
• PID Calculations.
• Advanced Subroutines
• BIT Operations.
• Data Transfer.
• Text Handling.
• Cost of hardware, software, Integration Engineering, Design, Installation, Start-up and Commissioning, Validation documentation and Execution, Training, Spare parts, Maintenance, System service contract and system life cycle.
• Reliability, Flexibility, Scalability and Validatability.
• Ease of Database configuration, Graphics development, Interlocks and Batch processing.
• Integration of High-level Application.
• Control Philosophy for Centralized versus Remote Operator Console or both.
• Compliance with an Industry batch standard such as ISA SP88 and new Communication Protocol.
PLC\DCS Selection Criteria
PROGRAMMABLE LOGIC CONTROLLERS
PLC • Sequentional logic solver
• PID Calculations.
• Advanced Subroutines
• BIT Operations.
• Data Transfer.
• Text Handling.
PLC Types• Nano (less than 1k RAM, 32 I/O)
• Micro
• Small
• Large (8 to 64k RAM, 512 I/O More)
Basic criteria for PLC Types• Memory Capacity
• I/O Range
• Packaging and Cost per Point
Applications :• Machine controls.
• Packaging.
• Palletizing.
• Material handling and similar Sequential task.
Advantages of PLC :• They are fast and designed for the rugged industrial environment.
• They are attractive on Cost-Per-Point Basis.
• These Devices are less Proprietary ( E.g.. Using Open Bus Interface.)
• These Systems are upgraded to add more Intelligence and Capabilities with dedicated PID and Ethernet Modules.
Disadvantages of PLC :• PLC were Designed for Relay Logic Ladder and have Difficulty with some Smart Devices.
• To maximize PLC performance and Flexibility, a number of Optional Modules must be added
• This Product Family also create Training and Installation problems.
PLC Types• Nano (less than 1k RAM, 32 I/O)
• Micro
• Small
• Large (8 to 64k RAM, 512 I/O More)
Basic criteria for PLC Types• Memory Capacity
• I/O Range
• Packaging and Cost per Point
PLC Systems Installation in RCF
1. Siemens --- Ammonia I
SIMATIC 115U
110U
2. Allen Bradley --- PGR,New Nitric Acid Plant
PLC 5/25 and 5/10
3. Allen Bradley --- KCL/DAP Bagging Plant,Ammonia I
SLC 5
4. GE Fanuc --- Ammonia Storage
90 - 30 Series
5. GE Fanuc --- New Bagging Plant
90 - 30 Series
6. Mitsubishi --- STP
PLC Cycle
Outputs
Machineor
Process
Programmablecontroller
Inputs
PLC Signal Flow
Programming Terminal
O:0/7
O:0/7
O:1/5
Output Devices
Output ModulesProcessor MemoryInput Module
Input DevicesLadder Program
O:0/7
O:1/5
I:0/6
I:1/4
O:1/5
I:0/6
I:1/4
I:0/6
I:1/4
Data InputImage Table
OutputImage Table
ALLEN BRADLEY PLC (DH+)
PLC-5 Controller
Workstation with RSLogix5 Software
Workstation
SLC-5/04 Controller
Features :
•Supports remote programming
•Common, existing standard
•Peer-to-Peer communications
Data Highway Plus
ALLEN BRADLEY PLC ARCHITECTURE (ETHERNET)
Modem
Internet
Laptop
PLC-5 Controller
Data Highway Plus
Ethernet Gateway.
PLC-5/20E Controller.
SLC-5/05 Controller.
PC Workstation
Ethernet
Comparison chart --- ALLEN BRADLEY PLC
MODEL TOTAL SYSTEM I/O
SCAN RATE/1K
PROGRAM MEMORY SIZE
DATA MEMORY SIZE
SLC500 72 8 ms 1K 4KSLC5/01 256 8ms 4K 16KSLC5/02 480 8ms 4K 16KPLC-5/10 512 2ms 6K 6KPLC-5/25 1920 2ms 21K 21KPLC-5/40 2048 0.5ms 48K 48KPLC-5/60 3072 0.5ms 64K 64KPLC-5/250 4096 <1ms 384K 384K
GE Fanuc - PLC
• GE Fanuc PLC Architecture : GE Fanuc ‘s series 90-30 PLC Family.
RemotePlatform
Host Platform
Wireless Modem
Wireless Modem
GE Fanuc 90/30 PLC
H M I Display
PC
GE Fanuc 90/30 PLC
90 - 70 PLC’s
Siemens PLC Communication
S5-115H S5-155H
S5-155US5-135U S5-100U
SINEC
Siemens PLC Architecture
Internal programMemory(RAM)
Memory submodule
Processor
ProcessImage
ForInputsAnd
Outputs
Timer
Counters
Flags
Inputs
ExternalCounters
Outputs
Program memory
I/O
I/O bus
Siemens Programming Methods
The program is generally written down before it is loaded into the programmable
controller. This can be done in the form of a
• Statement list ( STL )
• Control system flowchart ( CSF) or
• Ladder diagram ( LAD ).
The subsequent loading of the program into the S5-100U PC can take place in
two ways : Online ( Direct to internal RAM ) or Off-line ( EEPROM or EPROM ), i.e., with
the programmer connected or not connected to the programmable controller.
Siemens S5-100U Specification
CPU 100 U
Function range Boolean logic, bracketed operation, counter and timer functions, load, transfer, comparison and jump operation, arithmetic.
Programming language STEP 5
Methods of representation STL, CSF, LAD.
Execution time 70 msec.
Program memory ( Internal RAM )
1K
Flags 1024, ½ of which are retentive.
Digital Inputs
Digital Outputs
128 ( Max.)
Analog Inputs
Analog Outputs
8 ( Max.)
Comparison chart --- SIEMENS - PLC
MODEL TOTAL SYSTEM I/O
SCAN RATE/1K
PROGRAM MEMORY SIZE
DATA MEMORY SIZE
90U 8 2 msec 4 KB 4KB
95U 8 2 msec 16KB 16KB
100U 8 70 msec 2KB 2KB
102U 16 7 msec 4KB 4KB
103U 32 1.6 msec 20KB 20KB
135U 192 1.1 msec 46KB 64KB
155U 32578 0.2 msec 640 KB or
1.6 MB
640KB or 1.6MB
PLC Architecture Evolution• Mid - 1970s : Discrete Machine Control
ProgrammingTerminal
PLC
I/O
Connection is Point to Point
Programming Language :
- Relay ladder logic - Flexibility in altering control system operation
• Early - to - Mid 1980 : Discrete and Process Control
PLC Architecture Evolution
Reasonable ComputerRunning PLC
Programming Software
PLC
I/O
Programming Language :
- Ladder Program - PID - Data Storage
MS - DOS
PLC Architecture Evolution
• Late 1980’s to early 1990’s : Discrete and Process Control
PC running PLC Programming Software
PLC
I/O
Connection in networked allowing Multiple PLC
PLC became a part of the developing enterprise resource system
Windows
PLC Architecture Evolution
• Today : Enterprise Control
NT - Based PC running Control Development Software
CE Based Open Control Unit
I/O
Program Download Connection
Open Solutions
Ethernet - enterprise network connection
Ethernet
Ethernet was originally designed by Digital, Intel and Xerox (DIX) in the early 1970’s
and has been designed as a broadcast system. The original format for Ethernet was developed
in Xerox Palo Alto Research center (PARC), California in 1972. The two inventors were
Robert Metcalf and David Boggs.
Ethernet version 1.0 and 2.0 followed until the IEEE 802.3 committee re-jigged the
Ethernet II packet to form the Ethernet 802.3 packet. Nowadays you will see either
Ethernet II (DIX) format or Ethernet 802.3 format being used.
The ‘Ether’ part of Ethernet denotes that the system is not meant to be restricted only to
one medium type, copper cables, fiber cables and even radio waves can be used.
Briefly, stated Ethernet what is referred to as the Physical layer and the Data-link layers
protocols. The physical layer defines the cable types, connectors and electrical characteristics.
The Data link layer defines the format an Ethernet frames, the error checking method and the
physical addressing method. As Ethernet is only a Physical/Data link layer other protocols
need to be added on top of it to address the issues of routing, end-to-end data integrity and
house specific network task are carried out.
10Base5
Traditionally, Ethernet is used over ‘thick’ coaxial cable called 10Base5 ( the 10
denotes 10 Mbps, base means that the signal is baseband i.e, takes the whole bandwidth
of the cable, 5 denotes 500m maximum length ). The minimum length between stations
is 2.5m.
The cable is run in one long length forming a ‘Bus Topology’. The segments are
terminated by 50 ohm resistor and the shield should be grounded at one end only.
10Base2
Thin Ethernet (Thinnet) uses RG-58 cable and is called 10Base2 (the 2 denotes
200 mtr maximum length cable). Each station connects to the Thinnet by way of
Network Interface Card (NIC). At each station the Thinnet terminates at a T-piece and
at each end of the Thinnet run a 50 ohm terminator is required to absorb stray signals
thereby preventing signal bounce.
Ethernet
10BaseT
Nowadays, it is becoming increasingly important to use Ethernet across Unshielded
Twisted Pair (UTP) or Shielded Twisted Pair (STP), this being called 10BaseT (the T
denotes twisted pair). UTP is installed in star wire format and Ethernet Hubs with UTP ports
(RJ45) centrally located. Also there should be no more than a 11.5db signal loss and the
minimum distance between devices is 2.5 meters.
The advantages of the UTP/STP technology are gained from the flexibility of the
system, with respect to moves, changes, fault finding, reliability and security.
10BaseF
10BaseF standard developed by IEEE 802.3 committee defines the use of Fiber for
Ethernet. 10BaseFB allows upto 2 Km per segment and is defined for Backbone application
such as cascading repeaters. 10BaseFL describes the standards for the Fiber optic links
between stations and repeaters allowing upto 2 Km per segment on multimode Fiber.
Ethernet
The following table shows the RJ45 pin outs for 10BaseT :
RJ45 Pin Function Colour 1 Transmit White/Orange
2 Transmit Orange/White
3 Receive White/Green
4 Blue/White
5 White/Blue
6 Receive Green/White
7 White/Brown
8 Brown/White
Ethernet
Controller ControllerController
Controller
Workstation Workstation Workstation Workstation
Switched Hub
Segmented (star) topology Bus topology Ethernet Topology
PLC conceptual overview
Process Graphics
History &Trend
Alarm &Events
SCADA configuration
editor
Other Aspectsystem
ABB Siemens AllenBradley
GEFanuc ….
opc Modbus comliProtocol
xxProtocol
yy
SCADAserver
OPC server
OP Client SCADA ControlAspect
Real-time database
Process control Software characteristics The most important feature of process control system is that it needs to be reliable. The
process control system used has to be completely crash-proof and any changes in the
system need to be made on-line.
The process control needs to be made real time, which means that it can update the I/O
data table and process the control program in the time required by the process.
A process control system that is deterministic refers to whether the operating system
allows the highest priority task to work without interruption from task with lower priority.
Software offerings in the automation and the process control fields must be versatile and
open enough to address the needs of different applications.
Finally the chosen solution must deliver tangible, quantifiable values such as :
1. Reducing project implementation time and cost.
2. Improving time-to-market.
3. Achieving higher production and quality.
4. Cutting maintenance and training cost.
5. Increasing profits.
PC-based control system features
Unlike the other systems, PCs provide a more open architecture making them ideal for
improving, optimizing and integrating the overall automation process, as well as conducting
control task.
In addition PCs offer the following features :
• Lower cost.
• Ease of use.
• Graphical user interface.
• Easy integration of logic, motion and process control.
• Simplified application development.
• Software portability
• Independence from proprietary control system.
Using PCs enable the following functions,
• Millisecond time stamping which is essential to utilities.
• Real time control.
• Sequence of events.
• Alarming.
• Data collection.
Windows NT features
Windows NT is gaining ground in open control because of the following advantages :
• User acceptance.
• Corporate interoperability
• Ease of use.
• Connectivity.
• Scalability for small and large application.
However, Windows NT has the following disadvantages :
• Needs a lot memory and processing power.
• Optimized for office, not control, requirements.
• Requires a disk drive which may fail.
• Depends on single vendor.
• Reboots at unexpected times
• Unstable operating system.
QNX Features
QNX real-time operating system, has evolved from the first-ever micro-kernel operating
system for PCs into one of the best selling and most trusted operating systems for mission
critical application. Today, QNX is the real time operating system in industrial automation,
hand held devices, controllers and soft PLCs
QNX is recognized as :
• The fastest and most dependable real time operating system.
• The most proven high speed, deterministic real time kernel.
• Having a hard real time engine that gives PLC-style control.
• Enabling data acquisition with milliseconds resolution.
• Providing a fault-tolerant architecture on which you can run control, events, alarms in a virtually crash-proof environment.
PLC Programming Standards
The open, manufacturer-independent programming standard for automation is
IEC 61131-3. You can thus choose what configuration interface you wish to use when
writing your application :
• Ladder Diagram
• Instruction List
• Function Block Diagram
• Sequential Function Chart
• Structured Text
All users, be they plant electrician or computer scientists, thus have a configuration interface in which they can feel at home.
Industrial IT Trends
The availability of information is becoming increasingly crucial in the view of growing global
competition. In future, a decisive competitive edge can only be achieved by providing the
right information at the right time, in the right place and in the right form for the right person.
these leading- edge application are continuously optimized and repositioned.
Industrial IT consists of five components:
1. Engineering IT
2. Operation IT
3. Production IT
4. Optimization IT
5. Evolution / Information
ASSET OPTIMIZATION
Industrial IT Trend
Sales & Marketing
Planning & Scheduling
Plant & Process Eng.
Operation & Maintenance Distribution
Real-timeAutomation &Information
e-PRO
DU
CT
IVIT
Y
Business Systems
Plant