Final answer:
A non-retentive programmed timing function does not keep its accumulated value once the input signal is off, resetting to zero every time. It is opposite to retentive timers which maintain their value even after the input signal is turned off or disrupted.
Step-by-step explanation:
A non-retentive programmed timing function does not retain its accumulated value between input signals. In the realm of programming, especially when dealing with automation or control systems such as Programmable Logic Controllers (PLCs), timers are used to execute actions for specific periods. There are generally two types of timers: retentive and non-retentive. Retentive timers maintain their count even when the input signal is turned off or when there is a power interruption. On the other hand, non-retentive timers do not save their accumulated time once the input signal is turned off; the count is reset to zero every time.
This behavior is particularly important in scenarios where the continuity of a process is critical. For instance, if a non-retentive timer is used to track the duration of a specific part of a manufacturing process, any interruption would cause the timer to reset, potentially disrupting the process. When designing control systems, engineers must carefully choose between retentive and non-retentive timers based on the needs of the application.