Sending data from the DS back to the robot

[non847]

Here is the picture i have in mind:
i add a control input to the dashboard.
i type some value inside.
i push a button on the joystick that 'apply' the changes and the robot comply
to the value i wrote on the dashboard. say for example seting the degree of a servo.

i know how the change the data that is sent from the robot to the DS, and display any information i like on the dashbaord. but i want to do that in the opposite direction.

how do i do that?
help will be appreciated