Trigger function is the function that monitor the input bit of digital
I/O board by using the timer of OS, and notify the change about changed
bit to application.
The period and accuracy of timer monitor is controlled by function of OS.
Using trigger function, application needn't has the function of bit monitor
and compare logic.
If at one monitor period different bits are changed simultaneously, then
the notifications are notified from the low rank bit (logic bit 0).
Since the trigger function has lower response speed and accuracy than the
interrupt function,
except in special cases, such as when you need to respond to both rising
and falling,
there is not much benefit in using the trigger function for bits that can
be used for the interrupt function.
See Also
Interrupt Selection of Interrupt or Trigger The speed of a notifying interrupt