3. PLC A.pdf

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Sardar

AutomationSolutions

: 8-

-- --. 009647504555969009647504632358

: 20,, 6.

00201670550600020239125992

Kurdistan Vision

Industrial Automationand Control in

Construction Plants

www.sardarautomation.com

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Sardar Automation Solutions

Industrial Automation and

Control

1:PLC architecture and hardware & WiringStrategies

2:Basic PLC instructions3:PLC Ladder Logic Language I

4:PLC Ladder Logic Language II

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1. PLC architecture and hardware


Objectives:

Component.

Architecture.

Functionally. To Distinguish the features of IA

computation tasks.

Performance specification of CPU, IO,

MMI, and communication module. Function modules.

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Introductory remarks:

Nature of IA computation.

interfaced with physical signals.

slow/fast. complexity : lowmedium

repetitive and real-time tasks : mostlystatic scheduling, simple os.

critical in nature. ( worst case must beconsidered in it).

harsh environment.

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PLC architecture:

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Processor Module: Hardware features

Standard processor: 80186

CO-processor, IO processor

Ram, dual ported ram(read write at

same time). EPROM/EEPROM

Programmer port

Network port

back up Battery. Power supply, Internal/External

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Typical PLC system:

Multiple CPU units.

Communicationprocessors.

Rack Mounted IOmodules.

Power Supply

n n

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Basic Hardware Architecture:


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Data Bus & Address Bus:


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Processor Module : software Features

Counting: software UP/DN counters (0-999) up to 10100 khz.

Timing: several software times (ms-hours).

PID controls: Different configurations.

Program execution: Cyclic, TimeControlled, interrupt Driven.

Computational capabilities: lowercompared to normal PCs.


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Input Modules:

Converts process level signals to processor

levels.

Provides Isolation: Opto couplers.

fault indication for wire break.

Analog or Digital.

A/D converter to analog input modules: 12

bits.

Several channels :32/64 digital channels, 8analogs channels.

Special inputs: thermocouple, RTD, Encoder.


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Output Modules:

Convert Processor Level to Process level.

Isolation

Analog Voltage/ Current Drive: servo amps

Digital

Voltage/Current switching: Triac.

Potential free relay contacts ,NO,NC


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Analog IO modules:

Analog signal termination. PLC bus ports.

Simultaneous sample and hold.

Multiplexed AD conversation.

Analog/Digital output drivers.


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Distributed IO modules (remote IO):

Intelligent field mounted IOdevices.

Saving in cabling costs.

Prameterizable from processor/programmer.

Improve data integrity.

Positioning with analog/digitalencoders.

High speed counters.


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Function Modules:

independent modules that execute tasksindependently.

For precision and high speed tasks

precoded control laws self optimizing capability

Typical Application:

Stepper/servo control.

Multi-axis synchronization. Used along with distributed IO systems.


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Counter modules:

Multiple counters.

Count redouble on the fly.

High speed count.


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Data Paths:

Rack - Mount.

BackPlane connected with functionand i/0 modules.

Bus extension possible.

Rackslotchannel addressing.


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Man Machine Interface (MMI,HMI)

PLC modules have limited MMILEDs.

Operator panels

Push button.

Micro/ Multifunction.

Mobile.

Visualization software running on the pc.

SCADA systems with remote terminal

units. Panel PC with touch screen.


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MMI:


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n n

Programming Devices:

Handle held programmer

tabletop programmer


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Communication:

point-to- point/ bus/ network/ remote.

Modules support for different media:

Radio Co-ax

FO

Different protocols RS232, RS 422/485,

Industrial Ethernet Network 10mbp. Field Bus, CAN Bus, Profi Bus

Proprietary


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Advantages of distributed /network IO

Cost Saved on maintenance integrity ofhigh speed signals.

Cost save in cabling.

Local Sensor diagnostics.

Special functions like start up.

Centralized coordination/monitoring.


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PLC sizes production application ranges

1.micro PLCs

2.small PLCs

3.medium PLCs

4.large PLCs

5.very large PLCs


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2. Basic PLC instructions

Processor Scan:


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Memory Structure and Capacity:


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2. Basic PLC instructionsThe memory Overview:

The executive memory. Application memory.

The executive and scratch pad areas are hiddenfrom the user and can be considered a singlearea of memory that, for our purpose, is calledsystem memory. On the other hand, the datatable and user program areas are accessible andare required by the user for control applications.They are called application memory.


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2. Basic PLC instructionsMemory map:

Executive Area. The executive is apermanently stored collection of programsthat are considered part of the system itself.These supervisory programs direct systemactivities, such as execution of the controlprogram, communication with peripheraldevices, and other system housekeepingactivities.


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Memory map: Scratch Pad Area. This is a temporary storage

area used by the CPU to store a relatively

small amount of data for interim calculations

and control. The CPU stores data that is

needed quickly in this memory area to avoidthe longer access time involved with

retrieving data from the main memory.


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2. Basic PLC instructionsMemory map:

Data Table Area. This area stores all dataassociated with the control program, such astimer/counter preset values and other storedconstants and variables used by the controlprogram or CPU. The data table also retains

the status information of both the systeminputs (once they have been read) and thesystem outputs (once they have been set bythe control program).


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Memory map: User Program Area. This area provides

storage for programmed instructionsentered by the user. The user programarea also stores the control program.


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Application Memory Map:


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Input Table:


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Output Table:


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Storage Area Table:


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Sample: Closed Limit switch to an internaloutput

3. PLC A.pdf

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