Written Assignment 5 PLC Seth Reehs
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Feb 20, 2024
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Chapter 7
2. Draw the symbol and explain the operation of each of the following timed contacts of a mechanical timing relay:
a. On-delay timer—NOTC contact Contact is open when relay is de-energized
b. On-delay timer—NCTO contact Contact is closed when coil id de-energized
c. Off-delay timer—NOTO contact Contact is NO whe coil is de-energized
d. Off-delay timer—NCTC contact
Contact is NC when coil is de-energized. 3. Name five pieces of information usually associated with a PLC timer instruction
1. Type of timer
2. Timer address
3. Time base of the timer
4. Preset value
5. Accumulated value
4. When is the output of a programmed timer energized?
When the preset time equals the accumulated time
5. a. What are the two methods commonly used to represent a timer instruction within a PLC’s ladder logic program? Coil and Block format
6. a. Explain the difference between the operation of a non-retentive timer and that of a retentive timer. A non-retentive timer adds time whenever the device is powered but does not retain the current time when the device loses power. In contrast, a retentive timer accumulates time when the device is powered and retains the current time even if power is removed.
b. Explain how the accumulated count of programmed retentive and non-retentive timers is reset to zero.
The reset of a non-retentive timer occurs when there is a loss of logic continuity to the timer rung. On the other hand, a retentive timer is reset by a dedicated reset signal, which could be triggered by an external control element such as a push button or switch.
7. State three advantages of using programmed PLC timers over mechanical timing relays
1. Modifying their settings is a straightforward process.
2. The quantity of timers employed can be adjusted without necessitating any alterations to the wiring.
3. These timers boast high accuracy and repeatability in their timekeeping.
8. For a TON timer: a. When is the enable bit of a timer instruction true? The enable bit becomes true whenever the timer instruction is true.
b. When is the timer-timing bit of a timer instruction true?
The timer-timing bit is true when the accumulated value of the timer is in the process of changing.
c. When does the done bit of a timer change state?
The done bit transitions between states when the accumulated value reaches the preset value.
9. For a TOF timer: a. When is the enable bit of a timer instruction true? The enable bit is activated when the timer instruction is true.
b. When is the timer-timing bit of a timer instruction true? The timer-timing bit is activated when there is a change in the accumulated value of the timer.
c. When does the done bit of a timer change state?
The done bit is activated when the timer instruction is true, remaining active until the accumulated value
reaches the preset value.
10. Explain what each of the following quantities associated with a PLC timer instruction represents: a. Preset time The duration of the timing circuit.
b. Accumulated time The elapsed time since the timing coil was energized.
c. Time base
The speed at which the timer counts time (e.g., 1s, 5s, 10s, etc.).
11. State the method used to reset the accumulated time of each of the following:
a. TON timer Temporarily force the rung to go false.
b. TOF timer Temporarily trigger the rung to go true.
c. RTO timer
Implement a reset instruction with an identical address to the RTO timer, linking it to the input.
1. a. With reference to the relay schematic diagram in Figure 7-38, state the status of each light (on or off) after each of the following sequential events: I. Power is first applied and switch S1 is open.
II. Switch S1 has just closed. III. Switch S1 has been closed for 5 s. IV. Switch S1 has just opened. V. Switch S1 has been opened for 5 s.
PL1
PL2
PL3
PL4
On
Off
On
Off
On
Off
Off
On
Off
On
Off
On
On
Off
Off
on
On
Off
On
Off
b. Design a PLC program and prepare a typical I/O connection diagram and ladder logic program that will execute this hardwired control circuit correctly. 3. Study the ladder logic program in Figure 7-40 and answer the questions that follow: a. What type of timer has been programmed? An on delay timer
b. What is the length of the time-delay period?
10 seconds
4. Study the ladder logic program in Figure 7-41 and answer the questions that follow:
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a. What type of timer has been programmed?
On-delay timer without retention b. What is the length of the time-delay period? 10 Seconds
c. What is the value of the accumulated time when power is first applied? Zero
d. When does the timer start timing?
When rung 1 transitions from true to false
e. When does the timer stop timing and reset itself? When rung 1 transitions from false to true
f. When input LS1 is first closed, which rungs are true and which are false? Rungs 1, 3, and 4 are true, while rungs 2 and 5 are false
g. When input LS1 is first closed, state the status (on or off) of each output. SOL A off, SOL B on, R on, Y off
h. When the timer’s accumulated value equals the preset value, which rungs are true and which are false?
Rungs 1, 2, and 4 are true, while rungs 3 and 5 are false
i. When the timer’s accumulated value equals the preset value, state the status (on or off) of each output. SOL A off, SOL B off, R on, Y off
j. Suppose that rung 1 is true for 5 s and then power is lost. What will the accumulated value of the counter be when power is restored?
Zero
6. Study the ladder logic program in Figure 7-43 and answer the questions that follow: a. What is the purpose of interconnecting the two timers? The purpose of the interconnecting timers is to get a longer delay time than that of a single timer.
b. How much time must elapse before output PL is energized? The timers in rung 2 and rung 3 are linked. The timer in rung 2 is set to 2900 seconds, while the timer in rung 3 is set to 1780 seconds. Collectively, the two timers have a combined preset value of 4680 seconds.
c. What two conditions must be satisfied for timer T4:2 to start timing? After the completion of the 2900-second count on rung 2 and the transition of the DN status, the closing PB initiates the beginning of T4:2 for timing.
d. Assume that output PL is on and power to the system is lost. When power is restored, what will the status of this output be? The RTO instruction retains the timed count, continues counting upon instruction, and persists in counting even when power interruptions occur. Consequently, the output PL remains consistently in the on state as long as the contacts of PB1 are closed.
e. When input PB2 is on, what will happen? The reset instruction, RTO, is linked to rung 1. When PB2 is activated, the RTO is triggered, causing both timers to receive a command to reset their accumulated values.
f. When input PB1 is on, how much accumulated time must elapse before rung 3 will be true?
For rung 3 to become true, the accumulated time must reach 2900.
7. You have a machine that cycles on and off during its operation. You need to keep a record of its total
run time for maintenance purposes. Which timer would accomplish this? To maintain a record of a machine's on and off cycles during operation, a retentive on-delay timer would be effective.
8. Write a ladder logic program that will turn on a light, PL, 15 s after switch S1 has been turned on. 9. Study the on-delay timer ladder logic program in Figure 7-44, and from each of the conditions stated, determine whether the timer is reset, timing, or timed out or if the conditions stated are not possible. a. The input is true, and EN is 1, TT is 1, and DN is 0. - The timer's state in the mentioned condition is within the timing condition.
b. The input is true, and EN is 1, TT is 1, and DN is 1. The stated conditions are not feasible as DN and TT cannot be in the ON state simultaneously.
c. The input is false, and EN is 0, TT is 0, and DN is 0. The described conditions above suggest that the timer is in the reset state, given that EN, TT, and DN are all in the OFF state.
d. The input is true, and EN is 1, TT is 0, and DN is 1.
These conditions imply that the timer is in the timed-out state. With EN set to 1 and DN also at a state of
1, it indicates that the accumulated time has reached its preset value, marking the completion of the cycle.
10. Study the off-delay timer ladder logic program in Figure 7-45, and from each of the conditions stated, determine whether the timer is reset, timing, or timed out or if the conditions stated are not possible. a. The input is true, and EN is 0, TT is 0, and DN is 1. Given that the input is true, EN should transition to 1. However, in this condition, EN remains at 0. Therefore, the specified conditions are not achievable.
b. The input is true, and EN is 1, TT is 1, and DN is 1. If the input is true and EN is 1 while TT is also 1, it is not possible for DN to be in a state of 1.
c. The input is true, and EN is 1, TT is 0, and DN is 1. The mentioned conditions above suggest that the timer is in a reset state.
d. The input is false, and EN is 0, TT is 1, and DN is 1. - The aforementioned conditions indicate that the timer is in a timing state.
e. The input is false, and EN is 0, TT is 0, and DN is 0.
The conditions mentioned above indicate that the timer is in a timed-out state.
11. Write a program for an “anti–tie down circuit” that will disallow a punch press solenoid from operating unless both hands are on the two palm start buttons. Both buttons must be pressed at the same time within 0.5 s. The circuit also will not allow the operator to tie down one of the buttons and operate the press with just one button. (Hint: Once either of the buttons is pressed, begin timing 0.5 s.
Then, if both buttons are not pressed, prevent the press solenoid from operating.)
Chapter 8
1.
Name the three forms of PLC counter instructions, and explain the basic operation of each.
An Up counter is an output instruction that accumulates its count in increments with a false to true or off to on transition. A Down counter, on the other hand, is an output instruction that accumulates its count in decrements with the occurrence of an event. An Up-Down counter, also
known as a combined counter, adjusts its count based on its preset value, increasing or decreasing as needed.
2.
State four pieces of information usually associated with a PLC counter instruction.
Counter type provides details about the type of counter, whether it's an up-counter, down-
counter, or up-down counter.
- Counter address holds the counter's address.
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- Counter preset value, specified by an operator, is loaded into the memory location. It can also be viewed as the maximum or reference value for the count.
- Accumulated value is the value presented by the counter.
3. In a PLC counter instruction, what rule applies to the addressing of the counter and reset instructions? The addressing rule for the counter and reset instruction stipulates that the counter reset coil should
be specified at the same reference address as the counter intended for reset. The reset instruction becomes active whenever the condition in the CTR rung is true.
3.
When is the output of a PLC counter energized? The PLC counter output is triggered when a counting event occurs, and this event can be either an Up-count or a Down-count event.
4.
When does the PLC counter instruction increment or decrement its current count?
The PLC counter instruction will increase or decrease its existing count when a counting event occurs.
5.
The counter instructions of PLCs are normally retentive. Explain what this means.
The counter is linked to two input conditions for count and reset instructions. The functioning or counting sequence of all PLC counters relies on the leading edge of the input signal. In the case of a retentive counter, the value is preserved even after the processor restarts.
9. Identify the type of counter you would choose for each of the following situations:
a. Count the total number of parts made during each shift. Up Counter
b. Keep track of the current number of parts in a stage of a process as they enter and exit. Up-Down Counter
c. There are 10 parts in a full hopper. As parts leave, keep track of the number of parts remaining in the hopper.
Down Counter
Chapter 8 Problems
1. a. Counter Up Counter
b. Once the cumulative count reaches the predetermined value and C5:1/DN = 1 (50 items counted).
c. In the case of C5:1/DN = 0, indicating any time other than when the cumulative value reaches the preset value.
d. The value before the power loss (24) remains unchanged.
e. Assuming Rung 4 remained True throughout, the value is 0, as this is the reset instruction.
f. Every time Rung 1 transitions from False to True.
g. According to this diagram, the count can only be reset when I:1/2 is True, serving as the reset instruction.
2.
a. At the start, O/9 is activated since Rung 1 is initially true. However, upon processing Rung 2, O/1 is activated, causing Rung 1 to become false, and O/9 will be deactivated.
b. O/9 will stay inactive until the button is pressed once more.
3.
a. An up-and-down counter combination.
b. Input I:2/6.
c. Input I:3/8.
d. Input I:4/1.
e. Triggered when either the CTU or the CTD reaches 25, resulting in a DN=1 output.
f. Increment by 10 in the upward direction.
6.
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Related Questions
Name
Section 5-2: Line Diagrams-Signals,
Decisions, and Actions
In the following application, a temperature switch controls a heating contactor and a flow switch is used to
ensure there is enough air flow. If there is not enough air flow, an alarm is sounded. Complete the required
information.
1. List all the signal devices in the circuit.
2. List all the action devices in the circuit.
3. List the decision part of the circuit that automatically sounds the alarm if there is a problem.
4. When the heating element is on during normal operation, is the flow switch open or closed?
CIRCULATING
2
L1
FAN
TEMPERATURE
SWITCH
TR
HEATING
ELEMENTS
FLOW
SWITCH
-HOT AIR
PADDLE
AIR FILTER
NORMALLY CLOSED
FLOW SWITCH
65
ALARM
(SOUNDS IF NO FLOW FOR
15 SECONDS OR MORE)
Date
HEATING
CONTACTOR
TR
ON-DELAY
TIMER
SUPPLY AIR
COLD AIR
(3) TIME SET= 15 SEC
© 2014 American Technical Publishers, Inc.
All rights reserved
arrow_forward
Based on the timing diagram below, choose the correct statement regarding Timer Relay.
On
Coil
Power
ff
+ 5 →
Seconds
Closed
Contact
Status
Open
Time
Select one or more:
O a. This is the OFF-Delay Relay
O b. This is the ON-Delay Relay
O c. The relay can used in automatic gate at car parking application :- when sensor detect car already pass
by to parking area, motor to control gate closing will turn ON after a few minutes.
O d. When the coil energized, the relay contact will make connection at the same timing.
arrow_forward
In relation to the circuit presented below, mark the alternative(s) that you consider correct.
1 To enable actuator A2 to advance, it is necessary to switch valve V2 to the leftmost position and ensure that valve V1 is in its initial (intermediate) position.
2 Switching valve V2 to the leftmost position allows actuator A2 to advance, but for this to happen, valve V1 must also be switched to the leftmost position.
3 When activating valve V1, using the locking lever installed on the left side of it, the two actuators (A1 and A2) are allowed to advance.
4 Hydraulic pump B1 is a simple variable displacement type.
5 Valves V1 and V2 have a TANDEM center.
arrow_forward
Problem Description
Components are to be continuously stamped with a stamping device. After the start button is
pressed, the die is pushed down and the component is stamped. The die is to return to initial position after
five (5) seconds.
The sequence stops automatically after five (5) cycles. Start button should reset the counter. Inductive
sensors S1 and S2 are used to check the fully retracted and extended positions of the cylinder.
Draw the following:
Pneumatic circuit diagram
Electrical circuit diagram
arrow_forward
FLUID POWER SYSTEMS
arrow_forward
Circuit Problem and Description: Using the given components, design a pneumatic circuit
which will operate a double acting cylinder (A) from any one of two identical valves. The
double acting cylinder will move out when either push button (M1) or (M2) is pressed, or
when they are pressed at the same time. When the buttons are released, the cylinder will
return to the initial position.
Materials:
Part #
Component Description
Quantity
SAI 2026 Double acting cylinder
SAI 2015 Normally closed 3/2 way valves operated by push button
SAI 2023 Pneumatically piloted 5/2 way monostable valve
SAI 2007
2
1
"OR" logic function valve
1
Teske
Circuit Problem and Description: Using the given components, design a pneumatic circuit
which will correctly and safely operate this machine control application. WWith this circuit, it
must be possible to regulate the delay of a double acting cylinder (A). The cylinder will be
driven by a valve, actuated by two pneumatic push buttons. One of the two push buttons…
arrow_forward
A single-acting cylinder of 25 mm diameter is to clamp a component when a push button is pressed. As long as the push button is activated, the cylinder is to remain in the clamped position. If the push button is released, the clamp is to retract. Draw the circuit diagram for the problem.
arrow_forward
QUESTION 27
Pneumatic timers have better repeat accuracy that electronic timers.
True
False
arrow_forward
2
arrow_forward
Chapter 18 Controlling a Preumatic System
461
Timing volume reservoir
Goodheart-Willcox Publisher
Figure 18-31, Timing-volume reservoirs allow ontrol of the sequence of a circuit using pilot-activated directional control valves.
arrow_forward
2) The continuous stopwatch timing method was used to obtain the observed times for a
worker-machine task. Only one cycle was timed. The data are recorded in the table below.
The times are listed indicate the stopwatch reading at the end of the element. Elements
a, b, and d are worker-controlled elements. Element c is machine controlled. Elements a
and d are external to the machine-controlled element, while element b is internal. Every
four cycles, there is an irregular worker element that takes 1.32 min rated at 100%
performance. For determining the standard time, the PFD allowance is 15% and the
machine allowance is 30%. Determine
a. The normal time
b. Standard time for the cycle
c. If worker efficiency is 100%, how many units will be produced in one 8-hour shift?
d. If the actual time worked during the shift is 6.86 hours, and the worker
performance is 125%, how many units will be produced?
Description of
Worker
Time
Description of
(min) Rating (%) Element Machine Element
Worker…
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Need circuit and explain each question...if you do this 2 questions I'll definitely rate your Answers surely no doubt
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Which one of the below statements is true?
O a. Kutzbach formula (or criterion) is always reliable in predicting the actual degrees of freedom for any mechanism.
Ob. Springs are considered as links for degree-of-freedom calculations.
Oc. For a grounded link rotating with constant angular speed, the magnitude of the velocity vector of a point increases as the point moves away from the pivot.
Od. Satisfying the Grashof criterion means that none of the links in a mechanism makes full rotations.
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Define the following examples as path, motion, or function generation cases:
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State four advantages of a pre-engaged starter when compared with an inertia type.
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Urgent urgent please
arrow_forward
QUESTION 12
Which one of the below statements is true?
O a. Kutzbach formula (or criterion) is always reliable in predicting the actual degrees of freedom for any mechanism.
Ob. Springs are considered as links for degree-of-freedom calculations.
Oc. For a grounded link rotating with constant angular speed, the magnitude of the velocity vector of a point increases as the point moves away from the pivot.
Od. Satisfying the Grashof criterion means that none of the links in a mechanism makes full rotations.
arrow_forward
All terminals have a defined wire size range. If I had a wire of 2.0mm / 15 AWG, what terminal should I use?
A. Red insulated terminal.
B. Blue insulated terminal.
C. Yellow insulated terminal.
D. It doesn’t matter as all these answers are correct.
arrow_forward
QUESTION 22
One of the oldest methods of timing is with a pneumatic timer.
True
False
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- Name Section 5-2: Line Diagrams-Signals, Decisions, and Actions In the following application, a temperature switch controls a heating contactor and a flow switch is used to ensure there is enough air flow. If there is not enough air flow, an alarm is sounded. Complete the required information. 1. List all the signal devices in the circuit. 2. List all the action devices in the circuit. 3. List the decision part of the circuit that automatically sounds the alarm if there is a problem. 4. When the heating element is on during normal operation, is the flow switch open or closed? CIRCULATING 2 L1 FAN TEMPERATURE SWITCH TR HEATING ELEMENTS FLOW SWITCH -HOT AIR PADDLE AIR FILTER NORMALLY CLOSED FLOW SWITCH 65 ALARM (SOUNDS IF NO FLOW FOR 15 SECONDS OR MORE) Date HEATING CONTACTOR TR ON-DELAY TIMER SUPPLY AIR COLD AIR (3) TIME SET= 15 SEC © 2014 American Technical Publishers, Inc. All rights reservedarrow_forwardBased on the timing diagram below, choose the correct statement regarding Timer Relay. On Coil Power ff + 5 → Seconds Closed Contact Status Open Time Select one or more: O a. This is the OFF-Delay Relay O b. This is the ON-Delay Relay O c. The relay can used in automatic gate at car parking application :- when sensor detect car already pass by to parking area, motor to control gate closing will turn ON after a few minutes. O d. When the coil energized, the relay contact will make connection at the same timing.arrow_forwardIn relation to the circuit presented below, mark the alternative(s) that you consider correct. 1 To enable actuator A2 to advance, it is necessary to switch valve V2 to the leftmost position and ensure that valve V1 is in its initial (intermediate) position. 2 Switching valve V2 to the leftmost position allows actuator A2 to advance, but for this to happen, valve V1 must also be switched to the leftmost position. 3 When activating valve V1, using the locking lever installed on the left side of it, the two actuators (A1 and A2) are allowed to advance. 4 Hydraulic pump B1 is a simple variable displacement type. 5 Valves V1 and V2 have a TANDEM center.arrow_forward
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