Sheridan College
Faculty of Applied Science and Technology
ENGI24495 – Control Systems
Assignment 4
This assignment is for your own study, to practice what you learned in the classes and to prepare for the
Final Exam. Do not hand in your solutions.
1. Which one of the following timer parameters represents the value that increments as the timer
is timing?
a) Accumulated time
c) Timer address
b) Preset time
d) Time base
2. The on-delay timer (TON) starts timing when the timer’s _______.
a) ladder rung switches from false to true.
b) ladder rung switches from true to false.
c) accumulated value equals its preset value.
d) accumulated is greater than its preset value.
3. The off-delay timer (TOF) starts timing when the timer’s _______.
a) ladder rung switches from false to true.
b) ladder rung switches from true to false.
c) accumulated value equals its preset value.
d) accumulated is greater than its preset value.
Figure 3: Timer program.
4. For the on-delay timer program shown in Figure 3, output B is switched ON when _____.
a) power is applied.
b) input A is closed.
c) the timer is accumulating time.
d) the accumulated value equals the preset value.
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5. In an up-counter, when the accumulated count exceeds the preset count without a reset, the
accumulated count will _______.
a) set itself to zero.
c) continue incrementing.
b) start decrementing.
d) hold the accumulated value.
6. A PLC down-counter (CTD) counter counts __________.
a) scan transitions.
c) false-to-true transitions.
b) true-to-false transitions.
d) both b and c
Figure 4: Counter program.
7. For the counter program of Figure 4, output PL2 will be energized ________.
a) until the accumulated value equals the preset value.
b) when the accumulated value equals the preset value.
c) only when the accumulated value exceeds 10.
d) only when the accumulated value is zero.
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Figure 5: Timer program for questions 8 - 11
8. For the timer program of Figure 5, the timer starts timing when _________.
a) PB1 is open.
c) SS1 is open.
b) PB1 is closed.
d) SS1 is closed.
9. When SS1 is closed, the time-delay period will be _______.
a) 0 s.
b) 5 s.
c) 10 s.
d) 15 s.
10. Rung No. 3 will be true ________.
a) 10 s after PB1 remains closed.
b) 5 s after SS1 remains closed.
c) 15 s after both PB1 and SS1 remain closed.
d) any time SS1 is closed.
11. Rung No. 2 tells the processor to set the preset time of the timer to _______.
a) 15 when SS1 is open.
c) 10 when SS1 is open.
b) 15 when SS1 is closed.
d) 10 when SS1 is closed.
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Figure 6: ladder program for question 12.
12. The logic rung in Figure 6 __________.
a) has logic continuity.
b) does not have logic continuity.
c) will cause output PL1 to be energized.
d) both a and c
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