hello this is the simplest aproach that i could think of :
there is comunication between program ( under the cnc control ) and ( computer) application
- cnc_program creates file1 with random content
- cptr_application detects the existance of file1, and displays the interface
- user selects something on the interface
- cptr_application is creating file2 with content2b, where content2b reflects the answer
- cnc_program is reading content2b from file2, and will do something based on user selection on interface
i hope is clear so far