Ok. This is progress. we learn that lower case AT commands are ok and that the line ending is \x0D. Use that instead of \n.

Did you follow my suggestion of reading the port settings (handshake, etc)? Make sure that the port is configured and "happy" - if not it won't send data. I would not introduce the complication of a config file at this early stage.

Again, trying running outside of Eclipse. That could make a difference.

please show the exact code that you are using for this testing.