Rockwell Automation DeviceLogix System User Manual - Manual (Page 105)

Publication RA-UM003B-EN-P - February 2010 105
Navigate the Old Ladder Editor Interface Chapter 4
Off Delay Timer
The Off Delay Timer works the same way as the On Delay Timer but
instead of delaying the true status of the output, it delays the false
status of the output. The input to this timer is a level sensitive false
with a level-triggered reset. This means that when the input is false,
the Timer increments the Accumulator and when the input goes true,
the Timer resets the Accumulator. Each Timebase unit of time, the
Timer increments the Accumulator. When the Accumulator reaches
the preset value, the Timer sets the output to false. The Timer
maintains the output false status as long as the input remains false.
When the Input changes from false to true, the Timer sets the output
true and resets the Accumulator. If the Input goes true before the time
period specified by the Timebase and Preset, the output remains true
and the Accumulator is cleared, essentially ignoring the input.
If the Timer senses a true level on the Reset Input at any time during
the operation of the Timer, it resets the output to false and clears the
Accumulator. Because the reset line is level sensitive, the Timer
remains reset until the Timer detects a false on the Reset input. Also,
because the input is level sensitive, the Timer will again begin to
increment the Accumulator if the reset line goes false while the input
remains false. However, because the reset logic already set the output
to false, the time delay has no effect because the output is already
false. If the input is true when the reset goes false, the Timer sets the
output to true. Refer to the illustration of the timer function for
clarification.
11+PT
Reset
Input
Accum
Output
Indicates events that occur simultaneously
15+PT
44022