This document discusses automation and programmable logic controllers (PLCs). It defines automation as using control systems like computers to replace human operators in industrial processes. PLCs are described as programmable devices that monitor inputs, make decisions based on their program, and control outputs to automate processes. The document outlines the history of automation from manual to hardwired to PLC control and describes the basic components and programming of PLCs like inputs, outputs, memory organization, and ladder logic.

1. AUTOMATION:
Automation is the use of control systems such as computers to control
industrial machinery and processes, replacing human operators. In the scope of
industrialization, it is a step beyond mechanization. Whereas mechanization
provided human operators with machinery to assist them with the physical
requirements of work, automation greatly reduces the need for human sensory
and mental requirements as well.
ADVANTAGES OF AUTOMATION:
The purpose of automation has shifted from increasing productivity and
reducing costs, to broader issues, such as increasing quality and flexibility in the
manufacturing process.
Automation is now often applied primarily to increase quality in the
manufacturing process, where automation can increase quality substantially.
For example, automobile and truck pistons used to be installed into
engines manually. This is rapidly being transitioned to automated machine
installation, because the error rate for manual installment was around 1-1.5%,
but has been reduced to 0.00001% with automation.
Hazardous operations, such as oil refining, the manufacturing of industrial
chemicals, and all forms of metal working, were always early contenders for
automation.
Application of Automation
Power generation

2. TRANSMISSION AND DISTRIBUTION:
Oil and gas industries

3. Process industries
Building automation

4. HISTORY OF AUTOMATION
MANUAL CONTROL

5. HARDWIRED CONTROL:
Prior to PLCs, many of these control tasks were solved with contactor or
relay controls. This is often referred to as hard-wired control. Circuit diagrams
had to be designed, electrical components specified and installed, and wiring lists
created. Electricians would then wire the components necessary to perform a
specific task. If an error was made the wires had to be reconnected correctly. A
change in function or system expansion required extensive component changes
and rewiring.
DRAWBACKS:
Bulky and complex wiring.
Difficult to change the logic.
Unreliable.
RELAY :
RELAY LOGIC – AND GATE:

6. ELECTRONICS CONTROL
Logic gates and Electronic Circuits are used
Ease of programming
Ease of maintenance
Drawbacks:
Difficult to Troubleshoot while Change the Logic of the Process
Difficult to expand
Not suitable for industrial conditions
PROGRAMMABLE LOGICAL CONTORL
What is a Programmable Logic Controller PLC?
PLC is a device, which is used to control a machine or process as per the
human control sequence. A PLC monitors inputs, makes decisions based on its
program, and controls outputs to automate a process or machine.
Advantages
• Smaller physical size than hard-wire solutions
• Easier and faster to make changes
• PLCs have integrated diagnostics and override functions
• Diagnostics are centrally available
• Applications can be immediately documented
• Applications can be duplicated faster and less expensively

8. PROCESSOR MEMORY ORGANIZATION
The memory of a PLC is organized by types.
The memory space can be divided into two broad categories:
Program and Data Memory:
Advanced ladder logic functins allow controllers to perform calculatins,
make decisions and do other complex tasks. Timers and counters are examples of ladder
logic functions. They are more comples than basic inputs contacts and output coils and
relay heavily upon data stored in the memory of the PLC.
PROGRAM FILES:
The user program will account for most of the memory of a PLC
system.
Program files contain the logic controlling machine operation.
This logic consistes of instructions that are programmed in a ladder
logic format.
DATA FILES:
The data file protion of memory stores input and output status,
processor status, the status of various bits and numerical data.

9. INPUT TABLE FILE OPERATION:
Processor continually reads current input status and updates input
image table file.
OUTPUT TABLE FILE OPERATION:
Processor continually activates or deactivates ouput status according
to output image table file status

10. PROGRAM SCAN:
During each operating cycle, the processor reads all inputs, takes these
values, and energizes or de-energizes the outputs according to the user
program. This process is known as a scan. Because the inputs can change at
any time, the PLC must carry on this process continuously.
1. I/O scan – records status data of input devices. Energizes output
devices that have their associated status bits set to ON (1)
2. Program scan – instruction are executed sequentially.
SCAN PROCESS:
The scan time indicates how fast the controller can react to changes in
inputs. Scan times vary with computer model and program content, and
length. If a controller has to react to an input signal that changes states twice
during the scan time, it is possible that the PLC will never be able to detect
this change.

12. When the inputs is closed, the input module senses a voltage and an ON condition
(1) is entered into the input table bit ‘0012’.
During the program scan the processor sets instructins ‘0012’ and ‘506’ to ON(1).
The processor turns light output ‘506’ ON during the next I/O scan.

13. KEYENCE
ADDRESS:
INPUTS:
0000 to 0015
0100 to 0115
0200 to 0215
0300 to 0315
0400 to 0415
OUTPUTS:
0500 to 0515
0600 to 0615
0700 to 0715
0800 to 0815
0900 to 0915
INTERNAL MEMORY BIT:
1000 to 1015
Upto
1900 to 1915
TIMERS:
TMR<add> space #<time> (0.1sec)
TMH<add> space #<time> (0.01sec)

14. TMS<add> space #<time> (0.001sec)
COUNTERS:
Up counter: C<add> space #<number of count>space<internal bit>
Up/Dwn counter: C<add>space#<number of count>
PROCEDURE FOR PROGRAMMING:

15. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1. Edit command/Lable
2. Edit line command
3. Show/Hide command
4. Jump to specified line/step
5. Find
6. Replace operand
7. Usage information
8. Edit list
9. compail
10. Show compilation error
11. Transfer to PLC

16. 12. Read from PLC
13. Plc monitor
14. Simulator
15. Display mode
16. Description of operation
1 2 3 4 5 6 7 8 9 10
1. N.O. contact OR input
2. NC contact OR input
3. NO contact input
4. NC contact input
5. Output coil
6. NC output coil
7. Input vertical connection line
8. Delete vertical connection line
9. Input Horizontal connection line
10. Delete Horizontal connection line
BASIC PROGRAMMES:
--| |-- NORMALY OPEN CONTACT
--| / |-- NORMALY CLOSED CONTACT
--( )-- COIL
EX: 1
When the switch (SW) is ON, the LOAD should ON (Rung 0001)
When the switch (SW) is OFF, the LOAD should ON (Rung 0002

17. Note: The all programming sequence should complete with ‘END’ AND ‘ENDH’.
LADDER LOGICS FOR DIGITAL GATES:
OR :
I1 I2 L
0 0 0
0 1 1
1 0 1
1 1 1
AND:
I1 I2 L
0 0 0
0 1 0
1 0 0
1 1 1

18. NOR:
I1 I2 L
0 0 1
0 1 0
1 0 0
1 1 0
NAND:
I1 I2 L
0 0 1
0 1 1
1 0 1
1 1 0
EX-OR: EX-NOR:
I1 I2 L
0 0 1
0 1 1
1 0 1
1 1 0

19. SWITCH CONTACTS:
EX 1: SW1= 0000, SW2= 0001, LD1 = 500, LD2 = 501
SW1 SW2 LD1 LD2
1 0 1 0
1 1 0 1
EX 2:
SW1 SW2 SW3 LD1 LD2 LD3
0 1 1 1 0 0
1 0 0 0 1 0
1 1 1 0 0 1
I1 I2 L
0 0 1
0 1 1
1 0 1
1 1 0