True/False
Indicate whether the
statement is true or false.
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1.
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A timer instruction starts running, or timing, when its input turns
false.
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2.
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External outputs are controlled by placing the timer instruction on the external
output’s rung.
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3.
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There are two basic types of timer instructions: retentive and
non-retentive.
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4.
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Off-delay timers are often used when a timing event must take place after a
machine function turns off.
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5.
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Retentive timers are used in applications such as tracking the total running
time of a motor.
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6.
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The Timer Name is the IP address assigned to the instruction.
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7.
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An on-delay timer starts incrementing its elapsed time (ET) after its input (IN)
turns true. Once the ET has reached the preset time (PT), the timer turns on its output
(Q).
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Completion
Complete each
statement.
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8.
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PLC timer instructions are internal output instructions that are used to provide
time _______ in a PLC program.
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9.
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Timers can control both external outputs and input contact ____________.
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10.
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When the timer times out, it can make NO and NC contact instructions on other
rungs change ________ using timer status bits.
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11.
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Timer instructions are often used in machine contrls to provide a time delay
between two ________ in a machine’s sequence.
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12.
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A non-retentive timer instruction does ______ retain its elapsed time if its
input turns false while it is timing. It resets to zero.
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13.
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A retentive timer _______ its elapsed time if its input turns false. When
the input turns true again, the elapsed time resumes incrementing.
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14.
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All timer instructions use a ______ format, which uses multiple inputs and
outputs.
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15.
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Ther timer input (IN) is used to ______ the instruction.
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16.
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The timer’s output (Q) turns on under certain conditions, depending on the
______.
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17.
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The Q output can be connected to an ________ coil on the same rung to turn it
on.
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18.
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The elapsed time (ET) is the amount of time that the timer has been
________.
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19.
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The preset time (PT) is the amount of time that the IN input must be _____,
before the timer turns its Q output on or off, depending on the type of timer..
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20.
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PLC programs can also use timer instruction instead of limit switches to
________ events.
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21.
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Time-driven sequencing is used to control operations that are based on
_______.
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22.
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Time-driven sequencing is also used in applications where actuator positioning
is not ________ enough to use limit switches for sequencing.
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Matching
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a. | Retentive On-Delay Timer | c. | Non-Retentive On-Delay
Timer | b. | Non-Retentive Off-Delay Timer |
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23.
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Timer starts to time when its input turns true. Its output turns on after
a preset time delay. If its input turns false, the timer resets to zero.
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24.
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Timer starts to time when its input turns true. Its output turns on after
a preset time delay. If its input turns false, the elapsed time is maintained and resumes when
the input returns to true.
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25.
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The timer turns on its output as soon as its input turns true. When the
input turns false, the output remains on for a preset amount of time and then turns off.
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26.
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Non-Retentive On-Delay Timer
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27.
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Non-Retenvive Off-Delay Timer
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28.
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Retentive On-Delay Timer
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