There is no way to do that. ASP.NET is a server side language.

You can use this in C# windows app or service. You may get help here. http://www.c-sharpcorner.com/UploadF...unication.aspx

In VB, you can use MSComm control (COM component).

i want to read RFID from the client side how it is possible

There may be some functions available in Javascript to deal with the COM ports. But you may need to take care of plenty of things such as fireawall exception, Javascript enabled web browser, etc.

These things are very easy to do in windows application. But never tried in web applications because such things are seldom needed or not needed for any websites.

There is no way that any modern browser has javascript functions allowing access to COM ports.