How to make log details when user attemt to change te data in form?

Hi friends...

I have a task in Ax2009

i have a form named as Form_1. In this form i have grid with datasoure of table WeekDetails

Now my question is:

when i change something in the grid which in  form i need to make the log details on another table with field name and table name of weekdetails but without using modified field in table?

How can i achieve this?????????

Could u Pls help me??????