automation lecture 4

8/13/2019 Automation Lecture 4

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Automation Lecture 4.


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transmitter

actuator

Structure of control system

Process

or plant

Material flow

sensorstransducer

actuating

unit

actuating

drive

controller

operator desk

Visualization software

SCADA (Supervisory control and data acquisition)

Simulation software

Control software

Standard signals

Variables


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Relay

When a current flows through the coil, the resulting magnetic

field attracts an armature that is mechanically linked to a moving

contact. The movement either makes or breaks a connection

with a fixed contact. When the current to the coil is switched off,

the armature is returned by a force approximately half as strong

as the magnetic force to its relaxed position. Usually this is aspring, but gravity is also used commonly in industrial motor

starters. Most relays are manufactured to operate quickly. In a

low voltage application, this is to reduce noise. In a high voltage

or high current application, this is to reduce arcing.


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PLC Programmable Logic

Controller

PLCs were invented as replacements for automated

systems that would use hundreds or thousands of relays,

cam timers, and drum sequencers. Often, a single PLC

can be programmed to replace thousands of relays.

Programmable controllers were initially adopted by the

automotive manufacturing industry, where software

revision replaced the re-wiring of hard-wired control panels

when production models changed.


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IEC 61131-3

Part 3 of IEC 61131 deals with programming languagesand defines two graphical and two textual PLCprogramming language standards:

Ladder logic (graphical) Function block diagram (graphical)

Structured text (textual)

Instruction list (textual)

The standard also defines both graphical and textualsequential function chart elements to organize programsfor sequential and parallel control processing.


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IEC 61131-3 Programming

languages /

Industrial Control Programming

Standardizing the way people work with controls


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IEC 61131-3 Programming

languages /

Industrial Control Programming...with support for people

with different background


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The IEC 61131-3 Programming

Languages

Instruction List Structured Text

Function Block Diagram Ladder Diagram

C:= A AND NOT

B

A BC

-| |--|/|----------------(

)

LD A

ANDN B

ST C

AND

A

C

B


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Sequential Function Chart, SFC

Powerful graphical

technique for

describing the

sequential behavior ofa control program

Used to partition a

control problem

Shows overview, also

suitable for rapid

diagnostics

Step 1 N FILL

Step 3

Step 2 S

Empty

Transition 1

Transition 2


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Program Organization


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PLC families example

Small compact PLC-s with low I/O capability

Small PLCs with extendable I/Os

Medium PLC-s

Large PLC-s

Process Stations


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Siemens LOGO


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Siemens Simatic S7-200


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Siemes Simatic S7-300


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Siemens Simatic S7-400


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Phoenix Products

RFC 400

IEC 350IEC 200

automation lecture 4

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