Planner-list Time granularity on tasks

[Noe Misael Nieto Arroyo <noe iservices com mx>]

Hi everybody, I'm new to this list.

I am playing with planner and I want to make a gant chart of my backup scripts (One script enters before another and we have to wait until another one finishes until we start synchronizing archives and so on...) 

On the duration of my tasks:
If I try to put 30 min, the program puts in ther 30 d
If I try to put 0.5h the program puts nothing on the entry and the upper lever task takes into account that time. However, that time is not very accurate (ie: three 0.5h tasks accumulate 1h).


So the question here is twofold:
I am using Planner for a different purpose that it's intended use ?
Otherwise:
How does Planner handle time granularity in the way I am trying to use?

My best regards to all of you
:)

Noe Nieto