Use DateTime Fields & variables.
--- Diferencia en días, horas, minutos y segundos de dos variables DATETIME() ---
http://www.portalfox.com/article.php?sid=140HTH.
>Hello, i'm having this issue and i don't know how to start to solve it.
>I'm having two datetime fields, i need to know the amount of minutes between >them with this considerations:
>- the laboral time is from 7 am to 18 pm
>- the not laboral days, such as hollidays, saturdays and sundays.
>How can i do this?
>Thanks for your help.