Hello Rajebdrakumar,

Well actually JoSAA and CSAB counselling are not related to each other. These are two different counselling proccesses. CSAB counselling starts after the end of JoSAA counselling. JoSAA is the main counselling process for admission to NITs,GFITs,IIITs and IITs. After it ends, CSAB counselling will begin for the admission of JEE Main qualified candidates. 

So as per your question, the category rank is considered when one applies for JoSAA. When comes to CSAB , they only take the candidates who have valid JEE Main scores.

You can go through this link and checkout the details regarding JoSAA counselling : https://engineering.careers360.com/articles/josaa-counselling

Also, you can visit this link and check the details regarding CSAB counselling : https://engineering.careers360.com/articles/csab

Hope I have cleared your query. Good Luck !!!