Well, I actually asked you six very specific questions, not just one. This is a technical forum, so "feelings" don't really belong here.
I think my observation about your comments are accurate. You show a complete lack of understanding of the issues involved. For example you thought that a termination character was a good option, even though the data does not seem to have a specific termination character to begin with.
Why do you make statements such as: "I think when the number of bytes to be read is not fixed than the reading mode should be CRLF. Apart from this no other mode is useful." without explaining your thought process. That statement is not correct and can potentially misguide future readers.
You say that "...but when i am tersting in immediate mode number of bytes at a time i can read is 3752 because i dont know why ??????" (I did not change the number of question marks here!). Again, since you are not telling us how you a testing (attach some code!) or even explain what "at a time" actually means, we cannot really tell what you are doing wrong. As I already said earlier, in immediate mode you simply need to loop and read again (appending the data e.g. in a shift register or streaming it to disk) until you can tell that all data has been received.
We cannot help if you don't give us enough information to solve the problem. So please answer my questions.
(Alternatively, if you think you found a solution to your problems discussed here, post your VI here so others can learn from it. Thanks.)