01-Overview of PLC System Training PLC Allen Bradley

DAY 1
SESSION 1

1-1

OVERVIEW OF AB PLC’S SYSTEM

Overview of AB PLC’s System

6 – 10 December 2010


WHAT IS PLC?
• Programmable Logic Controller (PLC) or programmable
controller is a computer-based device that used to control
industrial equipment.
• Used to replace relay functions.

1-2

• PLC controlling an equipment based on input/output status of
the equipment and logical program.

Overview of AB PLC’s System

6 – 10 December 2010


RELAY
• Relay was used for control logic.
• Relay is a simple device that use magnetic field to control the

switch.
• Contact that will be closed when the coil energized is called
normally open.
• Contact that will be closed when the coil wasn’t energized is
called normally closed.

1-3

Coil

Arus Listrik
Overview of AB PLC’s System

6 – 10 December 2010


1-4

HOW DOES RELAY CONTROL?

Overview of AB PLC’s System

6 – 10 December 2010


1-5

EQUIVALENCY BETWEEN RELAY
AND PLC PROGRAM

Overview of AB PLC’s System

6 – 10 December 2010


1-6

PLC SYSTEM ARCHITECTURE

Overview of AB PLC’s System

6 – 10 December 2010


BASIC COMPONENTS OF PLC
• Processor
• Memory

outputs

inputs

• Power Supply

I/O System

Power Supply

• I/O Interface
• Programming Device & Languages

PROCESSOR

Memory
Unit

1-7

Programming
Device

Overview of AB PLC’s System

6 – 10 December 2010


HOW DOES A PLC WORK ?
• Examine the status of inputs and outputs
• Controls some process or machine through outputs using
some control logic
• This control logic is executed periodically by the processor in
a predetermined sequential order

1-8

• User can change the control logic using a programming
language and it is stored in the program memory

Overview of AB PLC’s System

6 – 10 December 2010

PLC WORK

POWER ON

Sanity Check

STOP
Indikator On

Yes

Error
No

Save to
Memori

Scanning
All Inputs

Ladder Logic Solved

Outputs Change
Overview of AB PLC’s System

6 – 10 December 2010

1-9

Scanning
All Outputs


PLC WORK (2)
Real Input
POWER ON

Scanning
Input

New
Output

Overview of AB PLC’s System

1-10

Scanning
Operation
Execution!

6 – 10 December 2010


PROCESS CONTROL USING PLC

1-11

Input

• Use input from the
sensor to make logical
decision, and;
• Update the output to
drive the actuator

Output

When a process being
controlled, PLC:

Overview of AB PLC’s System

6 – 10 December 2010


TYPICAL CONFIGURATIONS FOR
PLC
Large
• Small Size:

Medium

• Up to 128 I/O
• Memory up to 2 KB

• Medium Size:
• Up to 2048 I/O

• Memory up to 32 KB
• Up to 16000 I/O
• Memory up to 2 MB
Small
Overview of AB PLC’s System

Micro
6 – 10 December 2010

1-12

• Large Size:


PROCESSOR & MEMORY
input bus

System
Clock

I/O
Port

•

80386/80486 microprocessor
based

•

Random Access Memory (RAM)

•

Electrically Erasable Programmer
Read Only Memory (EEPROM)

Overview of AB PLC’s System

Data
Memory

Program
Memory

address bus

Instruction Cycle :
• Fetch the next instruction from
program memory
• Place it in the instruction register in
the CPU
• Increment the program counter by
one
• Execute the instruction
6 – 10 December 2010

1-13

CPU

output
bus


ALLEN-BRADLEY PLC
PROCESSORS

SLC 5/03
• 1747-L53x
SLC 5/04
• 1747-L54x

• RS-232
• 1 DH-485 (1747-L53x)
• 1 DH+ (1747-L54x)
• 1 EtherNet/IP (1747L55x)

Networks Through
Additional Modules
• DeviceNet
• EtherNet/IP
Each interface uses an
RS-232 port.

SLC 5/03
• 1747-L55x
EtherNet/IP PLC-5
• 1785-LxxE

• RS-232
• 1 EtherNet/IP
• up to 2 DH+/Universal
Remote I/O

ControlNet PLC-5
• 1785-LxxC15

• RS-232
• 1 ControlNet
• up to 2 DH+/Universal
Remote I/O

DH+ PLC-5
• 1785-LxxB

• RS-232
• up to 4 DH+/Universal
Remote I/O

Overview of AB PLC’s System

• DeviceNet
• EtherNet/IP

Local
I/O

Total I/O
(Local and

Distributed)

32

local only

136

local only

540

additional I/O capacity
with DeviceNet I/O

512

3,072 additional I/O
capacity with
DeviceNet, ControlNet
and Universal Remote
I/O

1-14

Controller

Built-in
Communication
Ports

6 – 10 December 2010


ALLEN-BRADLEY PLC
PROCESSORS (2)
Controller

RS-232
1 EtherNet/IP
1 ControlNet
DH-485 (via RS-232)
Modbus via ladder
routine (via RS-232)

Local
I/O

• DeviceNet

960
digital

9000 digital
or
256 analog
additional I/O capacity
with DeviceNet I/O

512

128,000 digital
or
4,000 analog
additional I/O capacity
with DeviceNet I/O

512
digital

distributed I/O via
DeviceNet, ControlNet,
and EtherNet/IP

CompactLogix:
• 1769-L31
• 1769-L32C, 1769L32E
• 1769-L35CR, 1769L35E

•
•
•
•
•

ControlLogix:
• 1756-L55
• 1756-L61, 1756-L62,
1756-L63
• 1756-L60M03SE

• RS-232
• DH-485 (via RS-232)
• Modbus via ladder
routine (via RS-232)

•
•
•
•
•

FlexLogix:
• 1794-L34

• RS-232
• DH-485 (via RS-232)
• Modbus via ladder
routine (via RS-232)

• DeviceNet
• ControlNet
• EtherNet/IP

Overview of AB PLC’s System

Total I/O
(local and
distributed)

Networks through
additional modules

DeviceNet
ControlNet
EtherNet/IP
DH+
Universal Remote I/O

128
analog

1-15

Built-in
communication
ports

6 – 10 December 2010


1-16

ALLEN-BRADLEY PLC
PROCESSORS (3)

Overview of AB PLC’s System

6 – 10 December 2010

INPUT/OUTPUT SYSTEMS
• Discrete Inputs/Outputs
• Analog Inputs/Outputs
• Special Purpose Modules
• Intelligent Modules

1-17

• Communication Modules

Overview of AB PLC’s System

6 – 10 December 2010


DESIGNING I/O SYSTEMS :
ELECTRICAL
Input voltage rating
• Lists the magnitude and type of
signal the module will accept

Input current rating
• The minimum input current required
at the module’s rated voltage that
the field device must be capable of
supplying to operate the input
module circuit

Input threshold voltage

• The voltage at which the input signal
is recognized as being ON/true

Output voltage rating

Output current rating
• The maximum current that a single
output circuit in a module can safely
carry under load

Output power rating
• The maximum total power that an
output module can dissipate with all
output energized

Backplane current requirements
• Lists the current demand that a
particular I/O module internal
circuitry places on the rack power
supply

1-18

• The magnitude and type of voltage
that can be controlled within a stated
tolerance

Overview of AB PLC’s System

6 – 10 December 2010

DESIGNING I/O SYSTEMS :
MECHANICAL
Number of I/O points per module
Number of wires
Wire size specification
• Number of conductors
• Largest wire gage that the I/O terminal points will accept
Ambient temperature rating
• Based on the heat dissipation characteristics of the circuit
components inside the I/O module
• 0 - 60 C typical
Humidity rating

Overview of AB PLC’s System

1-19

• 5 - 95 % typical relative humidity

6 – 10 December 2010


PROGRAMMING DEVICES
Used to enter, store, and monitor the PLC software
PC-based system
Connected to the PLC only during :
• programming & testing
• startup

• troubleshooting
communication
cable

Overview of AB PLC’s System

6 – 10 December 2010

1-20

I/O Modules

TC

TC

TC

TC

AO

AO

AI

AI

AI

DO

DO

DO

DI

DI

PLC

DI

POWER
SUPPLY

DI

PLC
Communication
Card
Personal Computer


AB PLC PROGRAMMING SOFTWARE CONFIGURATION
RSLogix
Programming
Software

Driver :
- RS232
- RS 485
- ENET
- DH+

1-21

RSLinx
Communication
Software

Programming
& Communication
Software

Driver :
- RS232
- RS 485
- ENET
- Modbus

Overview of AB PLC’s System

6 – 10 December 2010


IEC1131-3 STANDARD LANGUAGES
Ladder Diagram (LD)
• Uses a standardized set of ladder logic symbols

Sequential Function Charts (SFC)
• Blocks connected together like a circuit diagram
Functional Block Diagram (FBD)
• A graphical language used to describe sequential operations
Instruction List (IL)
• Low level language
Structured Text (ST)

1-22

• High level structured language designed for automation processes

Overview of AB PLC’s System

6 – 10 December 2010


LADDER DIAGRAM (LD)
Representations of relay ladder diagrams
The most widely used
Composed of six categories of instructions

1-23

• Relay type
• Timer/counter
• Data manipulation
• Arithmetic
• Data transfer
• Program control

Overview of AB PLC’s System

6 – 10 December 2010


SEQUENTIAL FUNCTION CHARTS
(SFC)
• Represented as a set of well-defined steps, linked by
transitions

1-24

• Actions within the steps are detailed by using the Structured
Text language (ST)

Overview of AB PLC’s System

6 – 10 December 2010


FUNCTIONAL BLOCK DIAGRAM
(FBD)
• Describes a relationship or function between input and output
variables
• Well suited for many applications involving the flow of
information or data between control components
• Allows the programmer to build complex control procedures
• Extensive function blocks library is provided

ALM_01
ALM

0

...

Alarm

LV001

0
In

HHAlarm

90

0

90

HHLimit

HAlarm

HLimit

LAlarm

LLimit

LLAlarm

70
70

0
0
0
LLLimit

ROCPosAlarm

Deadband

ROCNegAlarm

10
10

Overview of AB PLC’s System

0

6 – 10 December 2010

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30

30