How to populate dropdown without triggering PAI event ?

Hi,

I have a screen with two fields- One input field and one drop down list field which has to be populated based on the value given in the first field.

How can I populate the drop down list dynamically based on first input field without pressing enter ( i.e with out triggering PAI event ) . I tried using DYNP_VALUES_READ in value request event.

Please give me your suggestions .