Instruction manual

Timers

114

890USE18300 September 2003

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 block is enabled and the trigger starts the accumulation, the block

will count a specified number of time units. The maximum number of unit counts

allowed is called the terminal count. The terminal count is a user-specified integer

value in the range 1 to 32 767.

When the block reaches the terminal count, the accumulator stops counting time

units and the output of the action turns off (0 if the output is standard, 1 if the output

is inverted). The output remains off as long as the timer accumulator holds the

terminal count.

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 accumulates to 240 ms,

then stops and holds its terminal count as long as the trigger remains at 0.

As the timing diagram above shows, the standard output falls to 0 (the inverted

output rises to 1) when the terminal count is reached. The standard output remains

0 (the inverted output remains 1) while the timer holds the terminal count. The

standard output is 1 (the inverted output is 0) whenever the timer is not at the

terminal count.

timer trigger

timer

output

240 ms

output

inverted