MicroLogix Packaged Controllers

1
Programmable Controller BasicsIntroduction

• MicroLogix Packaged Controllers

2
Traditional PLC Concept

• PLC performs relay equivalent functions
• PLC performs ON/OFF control
• Ladder diagram program representation
• Designed for industrial environment
• Designed for ease of use and maintenance

3
PLC Advantages

• Ease of programming
• Ease of maintenance
• Designed for industrial environment
• Quick installation
• Adaptable to change

4
Today's Higher Level Control Capability

• Arithmetic
• Data Comparison
• Word Manipulation
• Master Control Relay Instructions
• Program Skip Capability
• Sequencing
• Matrix Data Manipulation
• Proportional, Integral, Differential (PID) Control

5
What Is A Programmable Controller?

• A solid state device that controls output devices
  based on input status and a user developed
  program.
• Originally developed to directly replace relays
  used for discrete control.

Inputs
Outputs
Programmable Controller
6
Where do you Use a MicroPLC?

• Conveyor control
• Printed circuit board handling equipment
• SCADA(Supervisory Control And Data Acquisition)
• remote pump/lift station (water/wastewater)
• Flow monitoring for leak detection (oilgas)
• Strapping machinery / trash compactors
• Palletizers
• Compressor control
• Replace hard-wired relay panels or SBCs
• Many, many more

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Other Types of Control

• MicroPLCs vs. Relays
• above 2/3 relays cost becomes a problem
• panel space, cost
• limited functions
• limited logic, no math, no application specific
  instructions
• timers and counters cost to add
• no communications
• difficult to exchange data
• maintenance/reliability
• mechanical devices wear out, create and are
  affected by vibration
• expensive to program
• time consuming, difficult to document, hard to
  pass on logic
• difficult to troubleshoot
• requires skilled technician
• race problems are common and difficult to deal
  with

8
Other Types of Control

• MicroPLCs vs. Custom SBCs (single board
  computers)
• High design costs
• Contract or Staff with overhead and maintenance
  issues associated with each
• Repair / Service nightmare for customers
• Depending on markets served supplier must
  develop/support services
• High level of technical expertise required by
  technicians
• Specialized circuit boards require specialized
  equipment and technical staff
• Not readily available through distribution
  (typically regional)
• Suppliers sell the controller imbedded,
  replacement parts are not readily available even
  in emergency situations
• Typically does not meet worldwide standards
• Certifications cost money, typically a single
  controller does not warrant the investment.
  Volumes are not high enough and re-certification
  on each revision is unrealistic
• Typically a Domestic product
• Because of these issues many manufacturers limit
  themselves to a single market.

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Other Types of Controls

• Competing Control Systems
• Relays
• above 2/3 relays cost becomes a problem
• limited functions
• maintenance/reliability
• expensive to program
• difficult to troubleshoot
• Custom SBCs (single board computers)
• High design costs
• Repair / Service nightmare for customers
• High level of technical expertise required by
  technicians
• Not readily available through distribution
  (typically regional)
• Typically does not meet worldwide standards
• Typically a Domestic product

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Input Devices

• Pushbuttons
• Selector Switches
• Limit Switches
• Level Switches
• Photoelectric Sensors
• Proximity Sensors
• Motor Starter Contacts
• Relay Contacts
• Thumbwheel Switches

• 120/230 VAC
• 24 VDC
• Sourcing
• Sinking

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Output Devices

• Valves
• Motor Starters
• Solenoids
• Control Relays
• Alarms
• Lights
• Fans
• Horns

• Relays
• 120 VAC/VDC
• 240 VAC
• 24 VAC/VDC
• Triac
• 120/230 VAC
• Transistor MOSFET
• 24 VDC

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Inside A PLC
13
PLC Application Considerations

• Inputs/Outputs
• Type,
• AC, DC, sourcing, sinking, etc.
• Number of
• 10, 16, 20, 32, 156
• Memory
• Type
• Flash or Battery backed
• Size
• 1k, 6k, 12k, 16k, 64k

• Functions required
• Instruction set
• Messaging
• PID
• PTO, PWM
• Arithmetic
• Communications
• DeviceNet, Ethernet
• Remote I/O, DH
• Report generation

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PLCs Come in a Variety of Sizes...

• Pico
• Typically less than 20 I/O
• Micro
• Typically less than 32 I/O
• Small
• Typically less than 128 I/O
• Medium
• Typically less than 1024 I/O
• Large
• Typically greater than 1024 I/O

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And a variety of shapes/configurations

• Packaged
• MicroLogix 1000,1200 and 1500
• Packaged with expansion
• MicroLogix 1200 and 1500
• Modular (rack less)
• MicroLogix 1200 and 1500
• Modular (rack based)
• SLC 500 and PLC5
• Distributed
• SLC 500 and PLC5

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Packaged PLC

• Power supply, inputs, outputs and communication
  port are enclosed in a single package. Input and
  output devices are wired individually to the
  packaged controller.

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Packaged PLC With Expansion

• Base is identical to the standard Packaged PLC,
  but it also has the ability to drive additional
  I/O. The most common form of expansion is a block
  of I/O that uses the same base, or makes use of
  different types of expansion modules.

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Modular Rack-Less PLCs

• Identical in functionality to rack based PLCs
• Typically not as robust (packaging)
• Typically found on smaller (small and medium)
  sized PLCs.
• Will likely become the prevalent form of
  packaging in the future.

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Modular PLCs

• Mix N Match Components
• Processors, Power Supplies and I/O are plugged
  into a rack or chassis
• Available in Small, Medium, and Large platforms
• Flexibility results in higher costs when compared
  to packaged

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Distributed

• Rely on communications for EVERYTHING
• All I/O is connected to the processor through a
  High Speed data link.
• Typically found on larger (medium and large)
  PLCs.
• For certain applications this type of form factor
  is very advantageous.
• Usually higher cost for hardware, but much lower
  cost for system integration.
• RIO (Remote I/O), DeviceNet are examples of
  distributed control.

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Why use a Micro PLC

• Performance
• Although small in size these products can perform
  the same tasks as much larger PLCs
• Cost
• The price range for the entire family 200-800
  List
• Reliability
• Designed to meet existing industrial design
  standards
• UL, CSA, CE
• Designed manufactured in ISO9000 facilities
• International Focus
• Standard product available throughout the world

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Typical PLC Application
Solenoid 2
Solenoid 1
Motor
Ingredient A
Ingredient B
Sensor 1
Sensor 2
Solenoid 3
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Operation of Mixer

• Solenoid 1
• On Sol 3 is off, and Motor is off, and Sensor
  2 is off, and Auto Switch is on
• Off Sol 3 is on, or Motor is on, or Sensor 2
  is on
• Solenoid 2
• On Sol 3 is off, and Motor is off, and Sensor
  2 is on
• Off Sol 3 is on, or Motor is on, or Sensor 1
  is on
• Motor
• On Sensor 1 is on, and Solenoid 2 is off, and
  Solenoid 1 is off
• Off Solenoid 3 on

• Solenoid 3
• On Sol 1 is off, and Sol 2 is off, and Motor
  has run for 30 sec.
• Off Solenoid 3 has been on for 60 sec.

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Input Wiring
Isolation Barrier
Terminal Block
Input Devices
1
2
3
L1
4
PLC
5
L1
6
7
8
9
10
L2
COM
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Output Wiring
Terminal Block
Isolation Barrier
Output Devices
L1
OUT 1
L2
OUT 1
OUT 2
OUT 2
PLC
L1
OUT 3
L2
OUT 3
OUT 4
OUT 4
OUT 5
OUT 5
OUT 6
OUT 6
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PLC Operating Cycle
START
Housekeeping
Input Scan
Internal checks on memory, speed and operation.
Service any communication requests, etc.
The status of external inputs (terminal block
voltage) is written to the Input image (Input
file).
Program Scan
Output Scan
The Output Image data is transferred to the
external output circuits, turning the output
devices ON or OFF.
Each ladder rung is scanned using the data in the
Input file. The resulting status (Logic being
solved) is written to the Output file (Output
Image).