I want to specify start and finish date for the task only

Hello, the scheduler assumes 8 hours working day, i have different working hours for different days, and i want to exclude holidays and non working hour, I have made full server side scheduler, but I want to present the result to the end user, so I want to user dhtmlxScheduler for that purpose, can I specify the start and finish date without the duration in hours?

Unfortunately no, but you can use this simple formula:

duration = (date_end - date_start) * 8; 

on your server to specify the needed duration.
We will improve it once.