Question 1

For the programmed timers shown, the output of timer T4:5: 
A)turns on after a 10-s time delay and remains on.
B)turns off after a 2-s time delay and remains off.
C)turns on after a 3-s time delay and remains on.
D)is pulsed on and off at 1-s intervals.

Accepted Answer

The answer of For the programmed timers shown, the output...

Question 2

For the programmed timer circuit shown, the pilot light should come on: 
A)as soon as the switch is closed.
B)before the switch is closed.
C)for 15 seconds after the switch is opened.
D)as soon as the switch is closed and for 15 seconds after the switch is opened.

Accepted Answer

The circuit consists of a normally open switch (S1), a timer (IC1), a relay (K1), and a pilot light (PL1). When the switch is closed, power is supplied to the timer and it starts counting down. After the 1st timing cycle, the relay is energized and the pilot light is turned on. When the switch is opened, the timer is reset and continues to run for another 15 seconds. During this time, the relay remains energized and the pilot light stays on. Therefore, the pilot light comes on as soon as the switch is closed and remains on for 15 seconds after the switch is opened.

Question 3

For the program shown, the timer accumulated time is set to zero anytime: 
A)PB1 is closed.
B)PB2 is closed.
C)PB1 is open.
D)PB2 is open.

Accepted Answer

The answer of For the program shown, the timer accumulated...

Question 4

One of the advantages of using a PLC for timing circuit applications is the entire timing function occurs inside the controller.

Accepted Answer

PLCs are capable of executing timing functions within the controller itself without requiring additional timing components or external devices. This reduces the complexity and cost of the overall system as well as provides accurate and reliable timing control.

Question 5

The interconnecting of timers is commonly called:
A)grouping.
B)programming.
C)sequencing.
D)cascading.

Accepted Answer

The interconnecting of timers is commonly called cascading, meaning that the output of one timer is connected to the input of another timer, creating a cascade of timed events. Grouping and programming are not specific to interconnecting timers, and sequencing typically refers to the process of putting events in a specific order.

Question 6

For the programmed timer circuit shown, when the switch is initially closed motor(s) _____ start(s) immediately. 
A)M1
B)M2
C)M3
D)all of these

Accepted Answer

The answer of For the programmed timer circuit shown, when...

Question 7

The accuracy and repeatability of PLC timers are not as good as that of mechanical and electronic timing relays.

Accepted Answer

PLC timers have digital accuracy and repeatability, which are superior to mechanical and electronic timing relays that rely on mechanical components and suffer from contact wear and tear.

Question 8

For the program shown, the timer starts timing when: 
A)PB1 is closed.
B)PB2 is closed.
C)both PB1 and PB2 are closed.
D)either PB1 or PB2 is closed.

Accepted Answer

The answer of For the program shown, the timer starts...

Question 9

The type of timer program shown is a: 
A)retentive on-delay.
B)retentive off-delay.
C)nonretentive off-delay
D)nonretentive on-delay.

Accepted Answer

The timer program shown is a retentive on-delay timer. This is because it has a memory function that allows it to retain its timing value while the input signal is on, and only begins counting down once the input signal turns off.

Question 10

The main difference between a PLC retentive and nonretentive timer is that the:
A)retentive timer can be programmed for much longer time delay periods.
B)nonretentive timer can be programmed for much longer time delay periods.
C)retentive timer maintains the current time should power be removed from the device or when the timer rung goes false.
D)nonretentive timer maintains the current time should power be removed from the device or when the timer rung goes false.

Accepted Answer

A retentive timer, as its name suggests, retains the current time even if power is removed from the device or when the timer rung goes false. Nonretentive timers, on the other hand, reset to zero once power is removed or when the timer rung goes false. The length of time delay periods that can be programmed is not affected by whether the timer is retentive or nonretentive.

Question 11

When the timing of a device is not reset on a loss of power, the timing is said to be:
A)continuous
B)holding
C)retentive
D)saved

Accepted Answer

Retentive timing means that the timing is stored or remembered even in the event of a power loss. This is important for devices that must maintain a certain timing sequence or function, such as in industrial automation systems. Continuous timing refers to timing that is always running, regardless of power loss or other interruptions. Holding timing refers to a mode where the timing is paused or stopped, but can be resumed later on. Saved timing is not a commonly used term in the context of industrial automation systems.

Question 12

Which instruction can best be used to turn an output coil on or off after the rung has been false for a desired time?
A)RTO
B)TON
C)ON OFF
D)TOF

Accepted Answer

The TOF (Timer Off-Delay) instruction is used to turn an output coil on or off after the rung has been false for a desired time. It starts timing when the input condition becomes false.

Question 13

When addressing an RES instruction, it must be addressed to:
A)a TOF instruction.
B)a TON instruction.
C)any address other than that of the RTO instruction.
D)the same address as that of the RTO instruction.

Accepted Answer

An RES instruction must be addressed to the same address as that of the RTO instruction. This is because RES is used to reset the timer that was previously started by the RTO instruction at that specific address. If it is addressed to any other address, it will not reset the intended timer and may cause unexpected behavior in the program.

Question 14

The operation of a PLC retentive timer is similar to that of an:
A)electromagnetic pneumatic timer.
B)electromechanical motor-driven timer.
C)off-delay timer.
D)on-delay timer.

Accepted Answer

Electromechanical motor-driven timers, like PLC retentive timers, maintain their state (time value) even when the controlling signal is removed, allowing them to "retain" the timing operation progress similar to how a PLC retentive timer would.

Question 15

For the programmed timer circuit shown, assume the switch is closed for 5 seconds and than opened. After 12 seconds have elapsed motor(s) ____ will still be operating. 
A)M1, M2, M3
B)M2, M3
C)M3
D)none of these

Accepted Answer

The answer of For the programmed timer circuit shown, assume...

Question 16

The amount of time for which a timer is programmed is called the
A)preset.
B)desired time.
C)set point.
D)lapsed time.

Accepted Answer

The amount of time for which a timer is programmed is referred to as the preset.

Question 17

Unlike the TON timer, the RTO timer requires a(n):
A)timer reset instruction.
B)input condition instruction.
C)internal relay instruction.
D)instantaneous contact instruction.

Accepted Answer

The RTO (Retentive Timer On) timer requires a timer reset instruction to clear the accumulated time and restart the timer. This is in contrast to the TON (Timer On Delay) timer, which simply requires an input condition instruction to begin counting time. Therefore, the correct answer is A) timer reset instruction.

Question 18

RES instructions are used with:
A)TOF timers
B)TON timers
C)RTO timers
D)all of these

Accepted Answer

RES instructions are used with RTO (Retentive Timer On) timers to reset them, as they retain their accumulated value even after being de-energized.

Question 19

The main difference between a TON and TOF timer is that the:
A)TON timer can maintain its accumulated time on loss of power or logic continuity.
B)TOF timer can maintain its accumulated time on loss of power or logic continuity.
C)TOF timer begins timing when logic continuity to the timing rung is lost.
D)TON timer begins timing when logic continuity to the timing rung is lost.

Accepted Answer

The main difference is that a TOF (Timer Off-Delay) timer begins timing when logic continuity to the timing rung is lost, whereas a TON (Timer On-Delay) timer starts timing when it receives logic continuity.

Question 20

To reset a retentive timer, the:
A)AC time must be greater than the PR time.
B)PR time must be greater than the AC time.
C)AC time must equal the PR time.
D)none of these.

Accepted Answer

A retentive timer retains its accumulated (AC) value even when the controlling input is off. Resetting a retentive timer is not dependent on the relationship between the accumulated time and preset time (AC and PR times), but rather on a specific reset command or function within the control program. Therefore, none of the conditions listed (A, B, C) are correct for resetting a retentive timer.

Quiz 5: Programming Timers

For the programmed timers shown, the output of timer T4:5:

For the programmed timer circuit shown, the pilot light should come on:

For the program shown, the timer accumulated time is set to zero anytime:

One of the advantages of using a PLC for timing circuit applications is the entire timing function occurs inside the controller.

The interconnecting of timers is commonly called:

For the programmed timer circuit shown, when the switch is initially closed motor(s) _____ start(s) immediately.

The accuracy and repeatability of PLC timers are not as good as that of mechanical and electronic timing relays.

For the program shown, the timer starts timing when:

The type of timer program shown is a:

The main difference between a PLC retentive and nonretentive timer is that the:

When the timing of a device is not reset on a loss of power, the timing is said to be:

Which instruction can best be used to turn an output coil on or off after the rung has been false for a desired time?

When addressing an RES instruction, it must be addressed to:

The operation of a PLC retentive timer is similar to that of an:

For the programmed timer circuit shown, assume the switch is closed for 5 seconds and than opened. After 12 seconds have elapsed motor(s) ____ will still be operating.

The amount of time for which a timer is programmed is called the

Unlike the TON timer, the RTO timer requires a(n) :

RES instructions are used with:

The main difference between a TON and TOF timer is that the:

To reset a retentive timer, the: