Instruction manual

Timers

126

890USE18300 September 2003

Timer Reset

Input

The reset input is essentially a timer override mechanism. It may be a Boolean 1 or

0. The block is operational when the reset value is 1; it does not operate when the

reset value is 0.

The following timing diagram shows how the value of the reset input effects the

output from the block:

At the beginning of the timing sequence, while the reset input is 1, the standard

output rises to 1 (the inverted output drops to 0) while the block is accumulating The

standard output drops to 0 (the inverted output rises to 1) when the terminal count

(TC) is reached.

The second time that the trigger drops to 0, the timer begins to accumulate and the

standard output rises to 1 again (the inverted output drops to 0 again). But before

TC is reached the second time, the reset input drops to 0, thereby stopping the block

and sending the standard output to 0 (the inverted output to 1).

When the reset input rises back to 1, the timer begins to accumulate again starting

at 0, and the standard output rises again to 1 (the inverted output falls to 0). The

reset input restarts the timer because the state of the timer trigger input is high when

the reset goes high.

timer trigger

timer

output

reset

output

inverted