Instruction manual

Timers

890USE18300 September 2003 119

Time Units and

Terminal Count

You need to preset the timer block to accumulate in one of the following time units:

1ms

10 ms

100 ms

1000 ms

10 000 ms

When the timer is enabled and the trigger starts the accumulation, the block will

count a specified number of time units. This number is called the terminal count. The

terminal count is a user-specified integer value in the range 0 to 32 767.

For example, suppose you specify a time unit of 10 ms and a terminal count of 24.

When the timer trigger input drops from 1 to 0, the timer begins accumulating from

0 in 10 ms time units. It accumulates 24 time units (240 ms), then stops

accumulating and holds its terminal count.

As the timing diagram above shows, a standard output rises to 1 while the timer is

accumulating and falls to 0 whenever the timer is not accumulating. An inverted

output falls to 0 while the timer is accumulating and rises to 1 whenever the timer is

not accumulating.

timer trigger

240 ms

output

inverted

output