1. FUNCTION OF OUTPUT CONTROLLER AND APPLICATION
CHAPTER 5
FUNCTION OF OUTPUT CONTROLLER AND APPLICATION

2. TIMERS
Many applications in industrial control systems need timer functions.
Timer is used to activate or de-activate a device after a preset time interval.

3. TIMERS
Time delay relays and solid-state timers are used to provide a time delay.
Time Delay
Relay
Solid-State
Timer

4. QUANTITIES IN TIMER INSTRUCTION
Preset Time
Represents the time duration of the timing circuit.
e.g. if a time delay of 10 s is required, the timer will have a preset of 10 s.
Accumulated Time
Represents the amount of time that has elapsed since it is energized.

5. Time Base
Timers can typically be programmed with several different time bases: 1 s, 0.1 s, and 0.01 s are typical time bases.
E.g. if you enter 0.1 for the time base and 50 for the preset time the timer would have a 5 s delay (50 x 0.1 s = 5 s).

6. Generic Block-Formatted Timer Instruction
Timers are most often represented by boxes in a ladder logic.
Control line controls the actual timing operation of the timer.
Whenever this line is true the timer will time.
Preset time
Time base
Accumulated time
Retentive timer block
Output line
The timer continuously compares its accumulated time with its preset time. Its output is logic 0 as long as the accumulated time is less than the preset time. When the two become equal the output changes to logic 1.
Reset line resets the the timer's accumulated value to zero.

7. On-Delay Timing Relay Operating coil
Instantaneous
contacts NO NC
Nontimed contacts are controlled directly by the timer coil, as in a general-purpose control relay.
Time control
contacts NO NC
Time adjustment
When the coil is energized, the timed contacts are prevented from opening or closing until the time delay period has elapsed. However, when the coil is de-energized, the timed contacts return instantaneously to their normal state.

8. Timed Contact Symbols On-Delay Symbols
Normally open, timed closed contact (NOTC)
Contact is open when relay coil is de-energized
When relay is energized, there is a time delay in closing
Normally closed, timed open contact (NCTO)
Contact is closed when relay coil is de-energized
When relay is energized, there is a time delay in opening

9. On-Delay Timer Program
Ladder Logic Program L1 L2
TON
Input A
TIMER ON DELAY
Timer T4:0
Time base
Preset
Accumulated
Input A
Output B G EN DN 10
Output C R
T4:0
Output B EN
Output D Y
T4:0
Output C TT
T4:0
Output D DN

10. On-Delay Relay Timer Circuit (NOTC Contact)
Sequence of operation S1
S1 is opened, TD de-energizes, TD1 opens instantly, L1 is switched off.
S1 closes, TD energizes,
timing period starts,
TD1 still open, L1 is still off.
S1 open, TD de-energized,
TD1 open, L1 is off. L1
After 10 s, TD1 closes, L1 is switched on.
10 s
10 s
OFF ON
Input
Output
Timing Diagram

11. ? On-Delay Relay Timer Circuit (NCTO Contact) Sequence of operation
S1 closes, TD energizes,
timing period starts, TD1
is still closed, L1 is still on.
S1 is opened, TD de-energizes,
TD1 closes instantly, L1 is
switched on.
S1 open, TD de-energized,
TD1 closed, L1 is on. L1
After 10 s, TD1 opens,
L1 is switched off.
10 s
10 s On
Off
Input
Output
Timing Diagram ?

12. Timed Contact Symbols Off Delay Symbols
Normally open, timed open contacts (NOTO).
Contact is normally
open when relay coil
is de-energized.
When relay coil is energized, contact closes instantly.
When relay coil is de-energized, there is a time delay before the contact opens.
Normally closed, timed closed contacts (NCTC).
Contact is normally
closed when relay coil
is de-energized.
When relay coil is energized, contact opens instantly.
When relay coil is de-energized, there is a time delay before the contact closes.

13. Off-Delay Programmed Timer
The off-delay timer (TOF) operation will keep the output energized for a period after the rung containing the timer has gone false. EN DN
TOF
TIMER OFF DELAY
TIMER T4:3
Time base
Preset
Accumulated
I:1.0/0
O:2.0/1
T4:3/DN PL L1 L2
Input
Output
Ladder logic program S1 15

14. ? Off-Delay Relay Timer Circuit (NOTO Contact) Sequence of operation
S1 closes, TD energizes,
TD1 closes instantly,
L1 is switched on.
S1 is opened, TD de-energizes,
timing period starts, TD1 is
still closed, L1 is still on.
S1 open, TD de-energized,
TD1 open, L1 is off. L1
After 10 s, TD1 opens, L1 is
switched off.
10 s
10 s
Input
Output
Off On
Timing Diagram ?

15. ? Off-Delay Relay Timer Circuit (NCTC Contact) Sequence of operation
S1 is opened,
TD de-energizes, timing
period starts, TD1 is still
open, L1 is still off.
S1 closes, TD energizes,
TD1 opens instantly,
L1 is switched off.
S1 open, TD de-energized,
TD1 closed, L1 is on.
After 10 s, TD1 closes,
L1 is switched on. L1
10 s
10 s
Input
Output On
Off
Timing Diagram ?

16. NONRETENTIVE TIMER Is also known as TMR Has only 1 input
Timer enabled if the input logic is ON
Timer reset if the input logic is OFF
Non-retentive - loss of power flow to the timer causes the timer instruction to reset.
TMR
TIMER0 T0
K40
INPUT

17. RETENTIVE TIMER Also known as TMRA Has two inputs
Timer starts timing when ENABLE is ON
Timer stops when ENABLE is OFF without resetting the current value to 0.
Timer continues timing when it is enabled again.
The timer resets when RESET is ON (RES instruction is true)
Once RESET is OFF, timer enable to start
TMRA
TIMER2 T2
K50
ENABLE
RESET

18. Retentive Timer
A retentive timer accumulates time whenever the device receives power, and maintains the current time should power be removed from the device. Once the device accumulates time equal to its preset value, the contacts of the device change state. The retentive timer must be intentionally reset with a separate signal for the accumulated time to be reset.
Electromechnical Retentive Timer
Cam operated
contact
Motor-driven
cam
Once power is applied, the motor starts turning the cam. The positioning of the lobes determines the time it takes to activate the contacts. If power is removed from the motor, the shaft stops but does not reset.

19. EXERCISE

20. CASE 1
Using a timer, a toggle switch and a buzzer. Write a ladder diagram so that the buzzer will ON immediately, but OFF after 5 sec the input is OFF. Choose the type of timer necessary and assume the preset value for the timer is 0.1 sec.
Off Delay Timer (NOTO contact) is used
TMR
TIMER0 T0
K50 X0
INPUT
Y1=buzzer T0

21. When X0 ON the timer is enable, and starts timing. The buzzer starts.
CASE 2:
Q: Using a 2 inputs timer, a PB and a buzzer. The buzzer is needed to buzz for 5 sec. Assume that the preset value is 0.1 sec. Write the ladder diagram.
A: The ladder diagram is as below.
X0= PB
ENABLE
TMRA
TIMER2 T2
K50 T2
RESET X1
Y1=buzzer T2
Figure (b) Timer with 2 inputs
When X0 ON the timer is enable, and starts timing. The buzzer starts.
When X0 OFF the timer enable is off, and stop timing. But it does not reset to zero.

22. 5.1.2 Cascading Timer
Applications sometimes require longer time delays than one timer can accomplish.
Multiple timers can then be used to achieve a longer delay than would otherwise be possible.
One timer acts as the input to another.
When the first timer times out, it becomes the input to start the second timer timing.
This is called cascading.

23. When X0 is ON, timer will start timing. After 99 sec, Timer 1
CASE 3:
Q: One maximum timer can be set for 99sec. Let say preset value is 1 sec. Time needed to set is 150. In this case cascading timer is used. X0
TMR T0
K99 T0
TMR T1
K51
Figure (a) Cascading Timer
When X0 is ON, timer will start timing. After 99 sec, Timer 1
will trigger T0 to open. Then T0 will initiate Timer 1, and timing for another 51 seconds.
Usually used when requirements demand more time than is available from a single timer. Therefore, two or more timers can be programmed together to get the desire time.

24. CASCADING

25. CASCADING TIMER

26. The programming of two or more timers together is called cascading.
Timers may be interconnected, or cascaded to satisfy any required control logic.

27. Cascading Timers For sequencing Relay Schematic Diagram
Three motors started automatically in sequence with a 20-s time delay between each motor startup.
Relay Schematic Diagram

28. Cascading Timers For Longer Time Delays 30000
12000
30000
T4:1 max of seconds +
T4:2 of seconds
= seconds/
700 minutes

29. COUNTER
Electronic counters can count up, count down, or be combined to count up and down.
They are dependent on external sources, such as parts traveling past a sensor or actuating a limit switch for counting.

30. COUNTER APPLICATIONS

31. Block-Formatted Counter Instruction
Type of
counter
Preset value
Accumulated
value
Count line
Reset line
Output
line
PLC counters operate or count on the leading edge of the input signal. The counter will either increment or decrement whenever the count input transfers from an "off" state to an "on" state. The counter will not operate on the trailing edge, or on-to-off transition of the input condition.

32. Counter Counting Sequence
PLC counters are normally retentive. Whatever count was contained in the counter at the time of a processor shutdown will be restored to the counter on power-up. The counter may be reset, however, if the reset condition is activated at the time of power restoration.
PLC counters can be designed to count up to a preset value or to count down to a preset value.

33. Counter Counting Sequence
The up-counter is incremented by 1 each time the rung containing the counter is energized.
Counter Counting Sequence
The counter will increment until the accumulated value is equal to or greater than the preset value, at which time an output will be produced.

34. Counter Counting Sequence
The down-counter decrements by 1 each time the rung containing the counter is energized.
Counter Counting Sequence
A counter reset is always provided to cause the counter accumulated value to be reset to a predetermined value.

35. UP- COUNTER

36. Simple Up-counter Program7

37. Up-counter Program Timing Diagram

38. PLC-5 And SLC 500 Count-Up Counter Instruction

39. ControlLogix Count-Up Counter Instruction
The counter address in the PLC-5 and SLC 500 is a data table address, whereas in the ControlLogix it is a predefined structure of the data type.
In the PLC-5 and SLC 500, the max value for the preset and accumulated values is 32,767 and the min value is –32,768; for the ControlLogix controller the max value is 2,147,438,647 and the min value is –2,147,438,648.

40. RSLogic Counter Commands
CTU
Count-Up
Increments the accumulated
value at each false-to-true
transition and retains the
accumulated value when
power cycle occurs
CTD
Count-Down
Decrements the accumulated
value at each false-to-true
transition and retains the
accumulated value when
power cycle occurs
RES
Reset
Resets the accumulated
value and status bit of
the counter
HSC
High-Speed
Counter
Counts high-speed pulses
from a fixed controller
high-speed input
Command Name Description

41. Parts Counting Program
Counter C5:2 counts the total number of parts coming off an assembly line for final packaging
Each package must contain 10 parts
When 10 parts are detected, counter C5:1 sets bit B3/1 to initiate the box closing sequence
Counter C5:3 counts the total number of packages filled per day
A pushbutton is used to restart the total part and package count from zero daily

42. Parts Counting Program10 1 15 5 9

43. DOWN- COUNTER

44. Down-Counter
The down-counter output instruction will count down or decrement by 1 each time the counted event occurs. Each time the down-count event occurs, the accumulated value is decremented. Normally the down-counter is used in conjunction with the up counter to form an up/down counter.
Generic up/down counter program

45. Up/Down Counter Timing diagram
Preset Value = 3

46. Parking Garage Counter Program
As a car enters, it triggers the up-counter output instruction and
increments the accumulated count by 1.
As a car leaves, it triggers the down-counter output instruction and decrements the accumulated count by 1.
Since both the up- and down-counters have the same address, the accumulated value will be the same in both.
Whenever the accumulated value equals the preset value, the counter output is energized to light up the Lot Full sign.

47. Parking Garage Counter Program
150 38 50

48. Count-Down Counter Instruction
PLC-5 And SLC-500
Count-Down Counter Instruction
If the accumulation value is below the minimum range then the underflow (UN) bit will be true.

49. Up/Down-Counter Program
When the CTU instruction
is true, C5:2/CU will be true
causing output A to be true 1
When the accumulated value
is greater than or equal to the
preset value, C5:2/DN will be
true, causing output C to be
true 10
When the CTD instruction
is true, C5:2/CD will be true
causing output B to be true
Input C going true will cause
both counter instructions to
reset

50. In-Process Monitoring System
Before start-up, the system is completely empty of parts, and the counter is reset manually to zero.
When the operation begins, raw parts move through the in-feed
sensor, with each part generating an up count.
After processing, finished parts appearing at the out-feed sensor
generate down counts, so the accumulated count of the counter
continuously indicates the number of in-process parts.

51. In-Process Monitoring System5 8

52. Counting Beyond The Maximum Count
15000

53. Counter Speed The maximum speed of transitions you can count is
determined by your program's scan time. Any counter
input signal must be fixed for one scan time to be counted reliably.
If the input changes faster than one scan period, the count value will become unreliable because counts will be missed. When this is the case you need to use a high-speed counter.

54. CASCADING COUNTER

55. Cascading Counters
Depending on the application, it may be necessary to count events that exceed the maximum number allowable per counter instruction. One way of accomplishing this is by interconnection, or cascading, two counters.

56. Counting Beyond The Maximum Count
The output of the first counter is programmed into the input of the second counter
The status bits of both counters are programmed
in series to produce an output
These two counters allow twice as many counts to be measured

57. Cascading Counters For Extremely Large Counts
500 1
The output light turns on after 500 x 500, or 250,000 transitions of the count input
Whenever counter C5:1 reaches 500, its done bit resets counter C5:1 and increments counter C5:2 by 1