how can we use push button in gui for sending the serial data to microcontroller?

how can we use push button in gui for sending the serial data to microcontroller,since i am using the fwrite command in pushbutton callback for sending the data but its not working,so can anyone suggest something??

[Geoff Hayes]

Rahul - please copy and paste the pushbutton callback code to your question so that we can see what you have attempted to do. As well, please elaborate on what you mean by its not working. Are you observing an error, or is nothing happening? Try putting a breakpoint in the callback and then stepping through the code to see what is happening.