1. Industrial Electronics
DAE 32003
Industrial Electronics

2. PROGRAMMABLE LOGIC CONTROLLER
Chapter 4
PROGRAMMABLE LOGIC CONTROLLER
(PLC)

3. What is Programmable Logic Controller?
A Programmable Logic Controller is a microprocessor based system which uses a programmable memory for implementing specific functions such as logic, sequencing, timing, counting and arithmetic to control various types of machines or processes through analog or digital input / output modules.

4. PLC applications

5. Basic PLC components 1. Processor 2. Memory unit 3. Power supply
4. I/O module
5. Programming device

6. Basic PLC components

7. Typical PLC cabinet at site

8. PLC operations
A PLC monitors inputs, makes decisions based on its program, and controls outputs to automate a process or machine.
The operation of the PLC system is simple and straightforward. The processor or CPU completes three processes:
(1) Scans, or reads from the input devices,
(2) Executes or "solves" the program logic &
(3) Updates or writes to the output devices.
SCAN TIME
The scan time is a continuous and sequential process of reading the status of inputs, evaluating the control logic and updating the outputs. Scan time varies from 1msec to 30msec.

9. SCAN TIME
The scan time is a continuous and sequential process of reading the status of inputs, evaluating the control logic and updating the outputs. Scan time varies from 1msec to 30msec.

10. PLC advantages
PLCs are similar to computer but have certain features which are specific to their use as controller. These are:
They are rugged and designed to withstand vibrations, temperature, humidity, and noise.
The interfacing for inputs and outputs is inside the controller.
Easily programmed and easily understood programming language.

11. Mnemonic code

12. Mnemonic code

13. Mnemonic code examples

14. Mnemonic code examples

15. Mnemonic code examples

16. Convert the ladder diagram to mnemonic code
Activity
Convert the ladder diagram to mnemonic code
Answer

17. Convert the ladder diagram to mnemonic code
Activity
Convert the ladder diagram to mnemonic code
Answer

18. Convert the ladder diagram to mnemonic code
Activity
Convert the ladder diagram to mnemonic code

19. Hardware configuration of PLC

20. Hardware configuration of PLC
Lab training set

21. Programming software:
Methods to upload programs to PLC
OMRON
CQM1H
Programming console
Programming software:
CX programmer

22. OMRON
CQM1H
MEMORY MAP / ADDRESS
Lab training set

23. Ladder diagram structure
PLC instructions
Timer
Counter
Move
Compare
Add & Sub
Keep
Difu & Difd
Ladder diagram structure

24. PLC instruction: TIMER
Timer / Counter address is from TIM
TIM
Require a TIM number and a set value (SV).
For Omron CQM1H, SV must be between #0000 and #9999.
Value of parameter SV is multiplied by 0.1s, the result being total time in seconds.

25. PLC instruction: TIMER
Timer / Counter address is from TIM

26. PLC instruction: TIMER
Timer / Counter address is from TIM
Mnemonic code

27. PLC instruction: COUNTER
Timer / Counter address is from TIM
CNT
Require a CNT number and a set value (SV).

28. PLC instruction: COUNTER
Timer / Counter address is from TIM
CNTR(12)
Require a CNT number and a set value (SV).
Can count up, down and reset function.
CNTR is a reversible counter where both up count and down count can be down by the same counter

29. PLC instruction: COUNTER
Timer / Counter address is from TIM CP
CNT 007
#10
00004
00002
10010 (siren)
END
Mnemonic code LD LD
CNT #10
LD CNT OUT

30. Activity – Timer & Counter
An incoming bar for a parking lot will raise up for 20 seconds when sensor 1 detects an incoming car. After passing the bar, sensor 2 will start count up the number of cars that parks in the parking lot. At the exit sensor 3 will deduct out going cars from the parking lots. If at one time the number of cars in the parking lot is 20 then the full sign light will be on.
Sensor 2
Sensor 1
Sensor 3
Incoming
Outgoing

31. Activity – Timer & Counter

33. MOV(21) PLC instruction: MOVE
To move a data from one channel to another channel.
S : Source Channel
IR,SR,AR,DM,HR,TC,LR,#
D : Destination channel
IR,AR,DM,HR,LR

34. Transfer data from channel 000 to 100
P_On
MOV (21)
000
100
Transfer data from channel 000 to 100
Source input Channel 000
Destination Output Ch 100

36. Example
Display Error Code of Machine To Aid Tracing Source Of Problem.
Using MOV(21) instruction design :
Activation of error input signal to will sound an alarm and at the same time display the error code.
Input will reset the error code displayed after machine recovery from error.

37. 00001
00002
00003
RED LIGHT 10000
Alarm
Alarm Code #1
MOV(21)
#0001
101
#0002
#0003
#0000
00006
END
Alarm Code #2
Alarm Code #3
Reset Alarm Code Display

38. PLC instruction: COMPARE
CMP(20)
Compare is used to compare the data in a specific channel with the data in another channel or a four-digit hexadecimal constant.
Cp1: First Compare Word
IR,SR,AR,DM,HR,TC,LR,#
Cp 2: Second Compare Word
IR, AR, DM, HR, LR
CMP(20)
Cp1
Cp2

40. Example ADDR OP CODE DATA 0000 LD 25313 0001 OUT TR0 0002 CMP (20)
#0020
HR1
0003
AND
25507
0004
10001
0005
TR 0
0006
25506
0007
10002
25507 ( < )
TR0
CMP(20)
#0020
HR1
25506 ( = )
10001
10002
Green Light
Red Light

41. ADD(30) PLC instruction: ADD To add data in two different channel.Au Ad R
Au: Augend Channel
IR,SR,AR,DM,HR,TC,LR,#
Ad: Addend Channel
R: Result
IR,AR,DM,HR,LR

42. Example 1. The operation: HR000 #0001 #1234 HR000 #1235
ADD(30)
HR000
#1234
00007
ADDR
OP CODE
DATA
0000 LD
00007
0001
ADD(30)
0002
HR000
#1234
0003
END(01)
1. The operation:
HR000
#0001
#1234
HR000
#1235
2. Add # # = #1235
3. The result:
HR000
#1235

43. PLC instruction: SUBTRACT
To subtract data in two different channel.
SUB(31) Mi Su R
Mi: Minuend Channel
IR,SR,AR,DM,HR,TC,LR,#
Su: Subtrahend Channel
R: Result
IR,AR,DM,HR,LR

44. Example 1. The operation: HR000 #3234 #1234 HR000 #2000
SUB(31)
HR000
#1234
00007
ADDR
OP CODE
DATA
0000 LD
00007
0001
SUB(31)
0002
HR000
#1234
0003
END(01)
1. The operation:
HR000
#3234
#1234
HR000
#2000
2. Sub # # = #2000
3. The result:
HR000
#2000

45. KEEP(11) PLC instruction: KEEP To replace normal latching.
Has two input, set and reset.
Better use HR so the output retain even though power fails.
Set =00000
Reset=00001
KEEP (11)
IR/Output Port/HR
END

46. PLC instruction: DIFFERENTIATE UP
DIFU(13)
DIFU turns its output ON when it detects an OFF to ON transition in its input signal.

47. PLC instruction: DIFFERENTIATE DOWN
DIFD(14)
DIFD turns its output ON when it detects an ON to OFF transition in its input signal or from HIGH to LOW signal .

48. Exercise 1 Replace CNT with ADD and SUB.
A simple car park control system allows only a maximum of 30 cars parking spaces. Every time a car comes in, an incoming sensor will add 1 and any car that goes out an outgoing sensor will deduct 1. If the car park is occupied with 30 cars at one time, a full sign will be lighted up to inform there is no vacancy.

49. Answer

50. Exercise 2
Use KEEP instruction to solve these problems instead of normal latching.
A sensor is placed outside yellow line that enclosed the robot to provide safety cautions to the user. If the sensor detects someone crossing the yellow line the robot will automatically stop its operation and the siren will on until a reset button is pressed. Then the push button need to be pressed for robot to run again.
YELOW LINE
ROBOT
sensor

51. Answer

52. Exercise 3 Use DIFU and DIFD to solve the problem.
An automatic home garage is equipped with sensor 1, S1, that detects the approaching car and will open the garage until sensor 2, S2,detects the whole car body has safely parks inside the garage. S1 S2
Garage Door

53. Answer