For enabling the debug option in Weblogic , please add the following lines (written in bold) in startWebLogic.cmd in your domain's bin directory-
set JAVA_OPTIONS=-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,address=8453,server=y,suspend=n %SAVE_JAVA_OPTIONS%
And in eclipse modify the debug configuration port as 8453.
Hope it will work!
Thank you Prateek. I can move forward now with debugging some important source code.