Instruction manual

Timers
890USE18300 September 2003 113
Delay-to-stop Timer Block
Summary The delay-to-stop timer block starts a timing operation when its trigger falls from 1
to 0. The timer needs to be preset to accumulate a user-specified time unit for a
specified number of counts (the terminal count). The output of a delay-to-stop timer
block is a Boolean that goes to 0 as soon as the terminal count is reached and stays
at 0 as long as the terminal count is held. Optionally, you may invert the value of the
output.
Structure of a
Delay-to-stop
Timer Block
A block diagram for a delay-to-stop timer is shown below:
The timer block has three inputs—an enable input, a timer trigger and a reset. The
enable input allows or stops the output from being updated. The timer trigger is
essentially a timer start command. The reset input is a Boolean value that stops the
timer operation when it is 0.
The block also has two preset values (See Configuring Preset Values for a Reflex
Block, p. 27)—a time unit and a terminal count. The time unit needs to be specified
as some number of ms. The terminal count is a user-defined number of time units.
When a timing operation starts, it will accumulate time units from 0 up to the terminal
count. When the timer reaches the terminal count, the output turns off until the timer
looses the terminal count. When the timer looses the terminal count, it turns on.
The output is a Boolean value. The standard output is 0 while the timer holds the
terminal count and 1 when the timer looses the terminal count. The output may be
inverted.
enable
trigger
delay-to-stop timer
reset
time unit x terminal count output