Write a letter in A4 size paper for the need of CGPA into percentage conversion certificate. While writing a letter don’t forget to mention your NAME, REGISTRATION NUMBER, DEGREE, BRANCH, COLLEGE etc..
Take a Demand Draft(DD) with the instructions given by Anna university for the amount and payee details.
Write your NAME & REGISTRATION NUMBER on the backside of Demand Draft(DD).
Take a xerox copy of Consolidated certificate, Degree certificate, Transfer certificate (TC). If you don’t have degree certificate, you can use Provisional certificate instead of using Degree certificate.
Attach xerox copies and DD with the letter.
Submit the letter with necessary documents to the Transcript Section of Anna University. They will take a week to give you the required certificate. You can know whether the certificate is ready for issue or not by contacting Anna University Transcript Section.
While submitting the letter, they may ask you the original certificates, so having the original certificates at the time of submitting the letter is recommended.
Note : The above said procedure was followed in 2014, currently procedures might have changed. Hence it is recommended to verify with Anna university.