How to send only hexadecimal values as input through serial port ( com port ).

[l12ec937]

I want to take input from user through keyboard and send the same via serial port. Here how can I pass only hexadecimal values.

[Albert.Geven]

switch the display of the control to hexadecimal representation.

[l12ec937]

Thank you for reply, 

Can you elaborate it.

I'm taking input from keyboard from user by using string controls, how can I take only hexadecimal values by filtering. Here user can give any kind of input combinations but when only hexadecimal values gives then only we need  to pass these values through serial port.

[Albert.Geven]

right click on the string control and change the display mode to hex display

see lower on picture the red lined display
choose circled display mode