control systems may classify to open or closed loop, analog or digital. Yet we can classify control systems in other ways, which have to do with applications to. Process control Sequential control Motion control
FPGA==can prog by VHDL or VerilogClosed sys contain sensorz
PAC ==describes this new generation of industrial controllers that combines the functionality of a PLC and a PC.As the technological differences between PC and PLC wane, a new class of controllers is emerging for engineers who require higher loop rates, advanced control algorithms, more analog capabilities, and better integration with the enterprise network. The Programmable Automation Controller (PAC) describes this new generation of industrial controllers that combines the functionality of a PLC and a PC.
Open Frame PLC(Triangle Research Inc., Pte. Ltd.)single printed circuit board as shown in Figure 2-1.They are sometimes called single board PLCs or open frame PLCs. These are totallyself contained (with the exception of a power supply) and, when installed in a system, theyare simply mounted inside a controls cabinet on threaded standoffs. Screw terminals onthe printed circuit board allow for the connection of the input, output, and power supplywires. These units are generally not expandable, meaning that extra inputs, outputs, andmemory cannot be added to the basic unit. However, some of the more sophisticatedmodels can be linked by cable to expansion boards that can provide extra I/O. Therefore,with few exceptions, when using this type of PLC, the system designer must take care tospecify a unit that has enough inputs, outputs, and programming capability to handle boththe present need of the system and any future modifications that may be required. Singleboard PLCs are very inexpensive (some less than $100), easy to program, small, andconsume little power, but, generally speaking, they do not have a large number of inputsand outputs, and have a somewhat limited instruction set. They are best suited to small,relatively simple control applications.
(Omron Electronics) Modularized PLC
usually based upon the required inputs, outputs and functions of the controller. The first decision is the type of controller; rack, mini, micro, or software based. This decision will depend on After the planning phase of the design, the equipment can be ordered. This deci-sion is usually based upon the required inputs, outputs and functions of the controller. The first decision is the type of controller; rack, mini, micro, or software based. This decision will depend upon the basic criteria listed below.• Number of logical inputs and outputs.• Memory - Often 1K and up. Need is dictated by size of ladder logic program. A ladder element will take only a few bytes, and will be specified in manufactur-ers documentation.• Number of special I/O modules - When doing some exotic applications, a large number of special add-on cards may be required.• Scan Time - Big programs or faster processes will require shorter scan times. And, the shorter the scan time, the higher the cost. Typical values for this are 1 microsecond per simple ladder instruction• Communications - Serial and networked connections allow the PLC to be pro-grammed and talk to other PLCs. The needs are determined by the application.• Software - Availability of programming software and other tools determines the programming and debugging ease.The process of selecting a PLC can be broken into the steps listed below.1. Understand the process to be controlled (Note: This is done using the design sheets in the previous chapter).• List the number and types of inputs and outputs.• Determine how the process is to be controlled.
Tissue Packing Machine
ammonia and ethylene processing
This is an intro to a point in next session Errors fatal or non
Von Neumann architecture memory “memory-mapped I/O “accesses hardware by reading and writing to specific memory locations, using the same assembler language instructions that computer would normally use to access memory.
Is a device used to detect the presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. They are used extensively in industrial manufacturing. There are three different functional types, opposed, retro reflective, and proximity-sensing.
PLC, by Mohamed Al-Emam, Session 1
Session 01By Emamof Presented in 02-02-2009
TARGET TO CONTROL SYS. Automatic Controller WHAT Origin of PLC History Sizes of PLC’s Cycle of Operation Which APPLICATIONS N REAL PLC H.W Components: INPUT TO PLC ,SENSING CONCEPTS
Batch Processhas a beginning and an end “complete product control process” , Some applications require that specific quantities of raw materials be combined in specific ways for particular durations to produce an intermediate or end result.Example:production of food and medicine.
Continuous ProcessOften, a physical system is represented though variables that are smooth and uninterrupted in time.Example :control of the water temperature in a heating jacket,
DiscreteIt is Not independent, Most discrete manufacturing involves the production of discrete pieces of productExamples : metal stamping. automotive production.
Hybrid Applications having elements of discrete, batch and continuous process control are often called hybrid applications.
Sequential ControlControl a process that is a series of tasks to be performed (sequence of operation ),each task is performed under :- Time driven . Common in open loop sys Event driven . Common in closed loop sysExample washing machineIn PLC the SFC is powerful Lang for it .
Motion ControlControlling motion in electromechanical sys Rotational or Linear by Servomotor. Digital by NC (Numerical Control). 3 dimension by Robotic.
µC DCS PC Mr.CNC CONTROLLER PLC SCADA PAC FPGA
Automatic controllers µC==Microcontroller. FPGA not FBGA. PC Mr. PLC DCS== Distributed Control System SCADA == Supervisory Control And Data Acquisition CNC == Computer Numerical Control PAC ==Programmable Automation Controller
WHAT Programmable logic controllers, also called programmable controllers or PLCs, are solid-state members of the computer family, using integrated circuits instead of electromechanical devices to implement control functions. They are capable of storing instructions, such as sequencing, timing, counting, arithmetic, dat a manipulation, and communication, to control industrial machines and processes
Microprocessor The block that will have a built in capability to Add “multiply, divide, subtract”, and move its contents from one memory location onto another is called "central processing unit" (CPU).
Characteristics differentiatemicroprocessors Instruction set The set of instructions that the microprocessor can execute bandwidth The number of bits processed in a single instruction clock speed Given in megahertz MHz the clock speed determines how many instructions per second the processor can execute
MicrocontrollerA microcontroller (also MCU or µC) is a functional computer system-on-a-chip.It contains a processor core, memory, and programmable input/output peripherals.
Why Coz we can say Microcontroller= Microprocessor +Memory +i/o Peripherals. PLC’s=Microcontroller +I/O Interfaces.
Dick Morley==Richard E. MorleyFounder of Modicon (now Schneider Automation, Inc)
History of PLCs The first Programmable Logic Controllers were designed and developed by Modicon as a relay replacer for GM and Landis The first PLC, model 084, was invented by Dick Morley in 1969 The first commercial successful PLC, the 184, was designed by Michael Greenberg in 1973
Sequence of PLC control When a process is controlled by a PLC it uses inputs from sensors to make decisions and update outputs to drive actuators The process is a real process that will change over time. Actuators will drive the system to new states (or modes of operation). This means that the controller is limited by the sensors available, if an input is not available, the controller will have no way to detect a condition “real time system “.
Number Of Scan Special I/O Time Modules Memory Communications SoftwareNumber Of AvailabilityLogical I/O Select PLC Peripherals Type Of Controller
Scientific Experiments CERN LHC CERN built LHC 27Klm …this experiment is controlled by PLC
Also Martial Handling Plastic Machine Conveyor System Semi Conductors/IC Pump Control Manufacturing Paper And Pulp Industries Air Condition Control "For Glass Manufacturing Huge Sheller " Precast Concrete Generator Control System Industries Lift Control System Cement Manufacture Iron And Steel Manufacturing Printing Industries Traffic Light System Electro-plating Plants Power Stations Machine Tools
BUTthere is NO horizon for the Applications !!
PLC H.W Components: CPU =ALU +CU System Busses Memory I/O Sections Power Supply Unit Programming Device
Programming DeviceThe programming device is used to enter the required program into the memory of the processor.The program is DEVELOPED in the programming device and then TRANSFERRED TO MEMORY unit of the PLC.
CPUMicroprocessor based, allow arithmetic operations, logic operators, block memory moves, computer interface ,and local area network, functions,.. etc.CPU makes a great number of CHECK-UPS of the PLC controller itself so eventual errors would be discovered early.This is an intro to a point in next session
I/O SectionsInputs monitor field devices, such as switches and sensors.Outputs control other devices, such as motors, pumps, solenoid valves, and lights.
Power Supply UnitMost PLC controllers work either at 24 VDC or 220 VAC.Some PLC controllers have electrical supply as a separate module, while small and medium series already contain the supply module.Max current is 10mA.
MemorySystem (ROM) to give permanent storage for the operating system and the fixed data used by the CPU.RAM for data. This is where information is stored on the status of input and output devices and the values of timers and counters and other internal devices. EPROM for ROM’s that can be programmed and then the program made permanent.
System BussesThe internal paths along which the digital signals flow within the PLC are called busses.The system has four busses: The CPU uses the DATA BUS for sending data between the different elements, The ADDRESS BUS to send the addresses of locations for accessing stored data, The CONTROL BUS for signals relating to internal control actions, The SYSTEM BUS is used for communications between the I/O ports and the I/O unit.
$5 Moire Fringes These are used in high precision applications over long distances, often meters. They can be purchased from a number of suppliers, but the cost will be high. Typical applications include Coordinate Measuring Machines (CMMs).
6- Chemical pH The pH of an ionic fluid can be measured over the range from a strong base (alkaline) with pH=14, to a neutral value, pH=7, to a strong acid, pH=0. These measurements are normally made with electrodes that are in direct contact with the fluids.