i could run a ethernet sheild and did some projects like using it as a web server or turnig off & on an led and so on. in all these cases we send or receive a specific code can be changed in program not out of that now my question is that can we do the same thing as usart. i mean sending a message or code with ethernet sheild?
i mean sending a message or code with ethernet sheild?
You can't send code anywhere. That wouldn't make sense.
An example of what you want to send, to what, would be useful.
An Arduino wearing an ethernet shield can be a server, responding to GET requests, or a client, making GET requests. GET requests can contain a lot of data - look at the address bar sometime, when doing online shopping or googling.