I have a 8 input / 4 output audio matrix switch that I want to control from serial. I currently have a simple web page with buttons that link to different CGI scripts. When a button is pressed, it runs a script to output data to the serial port. I would like to have a page with (8) checkboxes on the left, named "Input 1" through "Input 8", and (4) checkboxes on the right labeled "Output 1" through "Output 4" and a "Submit" button. When a user checks "Input 1" and Output 4" for example, I need to send a command to the serial port as "CL2I1O4 T". The I1 corresponds to input 1, and O4 corresponds to output 4. The "T" is what finishes the command to the equipment to be controlled via serial, and the matrix switches as soon as the "T" is entered. These 2 numbers are the only thing that will change on the script based on user input. I made a page with the checkboxes and a submit button, but I am clueless on how to change the serial command output to serial based on user input. Any help would be greatly appreciated!