The main difference between a PLC retentive and non-retentive timer is that the:
A. retentive timer can be programmed for much longer time delay periods.
B. non-retentive time 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.
Show Answer
Answer: C
Share your understanding of this question with the correct explanation.
A retentive timer (also known as a cumulative timer) in a PLC (Programmable Logic Controller) maintains the elapsed time even if the power is removed from the device or if the timer rung goes false. This means that the timer will pick up from where it left off when power is restored or when the rung becomes true again. This is ideal for keeping track of accumulated time over multiple instances of the timer being energized.
In contrast, a non-retentive timer resets its accumulated time whenever the power is removed or when the timer rung goes false. This means that each time the rung becomes true, the timer starts timing from zero.
The duration that these timers can be set to doesn’t typically depend on whether they are retentive or non-retentive, which is why options A and B are incorrect. The maintenance or non-maintenance of time during power off or false rung states is the main difference between these two types of timers, making option C the correct answer.