How to find parameters of READ_TEXT function module

You need to know where to maintain the text to find the input parameters that you want to use for reading that text with function module READ_TEXT. You can ask the functional consultant as to where the text would be maintained by the user.

I am taking an example of maintaining text in billing document.

Go to T-code VF02. Enter the billing document number and press ENTER

Go to Header Texts 

Under the tab Head.text, find the text from the left pane that would be maintained. For example, I would be maintaining 'Form Header'. Double click Form Header and maintain the text value in the right pane and SAVE.

Repeat step 1 to 3. Before double clicking 'Form header', activate the debugger by typing '/h' in the command box.

Double click 'Form header' and when the debugger gets triggered, put a breakpoint at function module 'READ_TEXT'

Press F8. The debugger stops in the READ_TEXT function module. Press F7. Scrolling up you will find READ_TEXT function module. Double click the exporting parameters (OBJECT, NAME, ID, LANGUAGE) 

These are the values that we will be passing in our code to read the required text.