The block output (OUT_D) is set True when the input (IN_D) has been True for a specified time period (TIME_DURATION) while the RESET_IN input is False (0). When the RESET_IN input is False and the IN_D value transitions to False, the ELAPSED_TIMER stops and retains its value until IN_D transitions to True again. When the RESET_IN value transitions to True, the ELAPSED_TIMER is reset to zero and OUT_D is set False.
The following figure shows the timed response of the Retentive Timer function block:
