Know field exit with implementation of field exit

Field exit are use to create programming logic for any data element.It carry out any checks,Conversions or Business related processing of screen fields.

Important thing is it can not be debugged.It have its own naming convention FIELD_EXIT_.

In transaction code CMOD choose Text element -> Field exit.

For example : Suppose you want that in your R/3 system that all company location number should be greater than 50., then you have write a logic in field exit.When a field exit activates then it automaticlally check every time when user enters data.

Implementation of Field exit :

1. Enter the Project management transaction by choosing Utilities ->Enhancements ->Project management from the ABAP DevelopmentWorkbench menu.
2. Choose Text enhancements ->Field exits.
3. Choose Field exit ->Create.
4. Enter the name of data element.
5. Choose Continue. The system takes you into the Function Library and
suggests a name for your function module ( FIELD_EXIT_BBBNR ). You
should use this name.
6. Create the source code for your function module.
7. Activate the function module.

After you have created the processing logic for your field exit, you must assign the exit to one or more programs and screens. This assignment tells the system which screens to trigger your function module on. To assign your field exit module to one or more screens,proceed as follows:

1. Select the field exit.
2. Choose Assign prog./screen.
3. Enter the name of the program and the screen number.
4. ChooseSave.

For some fields, you might want to trigger a different processing logicon different screens. You can trigger screen-specific logic byallocating a field exit identifier when you make your screen
assignments. A field exit identifier can be any number or letter. Thefield exit identifier tells the system to trigger the function module thathas this identifier in its name.