User serial terminal

I am trying to develop my own application that has a built-in serial port terminal, but it will be able to pause the terminal and do some I / O in a custom command and data format.

eg. When I click the Get Data button, the software will send some binary command and return the binary data to it and render its data with the data. And the terminal will ignore this entire transaction.

As I just found out, simply writing () "ing to and read ()" from / dev / ttyxx is not enough to properly connect the terminal.

What's the easiest way to include a simple terminal in my application? I don't want to use an external terminal application. I am currently looking into the cutecom source code to implement it from scratch, but maybe there is an easier method.

Note: please do not suggest dilutions such as using xmodem / ymodem software, I have to use custom commands.