Interval Timer Question

[Damian]

Up until now, I have been using the 2.5ms counter to get the best resolution possible on timing functions.

However, I have always noticed that the Interval Timer Function gives a value in units of 10 microseconds.

Playing around a bit, I noticed that the interval FBs are fairly flexible (ie. they don't have to execute all on one scan, END can be processed before start without generating an error, you can have starts and ends in different locations, etc).

What I am wondering is, where is the counter the interval function is accessing.

I don't see any system word that has anywhere near that resolution. Why isn't it an SDW like the 2.5ms counter?

Also,

Why is the interval function presented as only a "DEBUG" function? It has potential usefulness in applications beyond use as a debug feature.

D