Alert on particular time

Hello,

I am very new to AFL this might be vary simple query but
I want to show Alert at say 13:30:00. How can do this? If I use TimeNum() and if there is no tick on 13:30:00 the alert will not be shown. How can I do this even if there is no tick on 13:30:00.

Using chart try using RequestTimedRefresh( xx, False ) and Now()