my purpose for compareAlarmInt is to scan the alarm value in loop function.
That does not describe a purpose, it says how you want to achieve a purpose but not why.
What do you want to achieve when you scan the alarm value in loop?
when I send serial messages, then Arduino will reset automatically?
You said above that you wanted to send VB messages to set the alarm. If you need help with aspects of your application that are not specific to the TimeAlarms library then its best to start a new thread so that the content of this one is focused on specific help with TimeAlarms.
I suggest your create a new thread and post a link here so I and others interested in your application can help.
Michael