Depends -
In the real event, the operator interface will be connected to a FIRST interface via the Competition port. All inputs, digital or analog, will be 127 and 0, respectively.
(Please search for more information on the inputs during autonomous mode in these forums. There is a wealth of information here.)
Also, the auton_mode bit, a bit of the PB_mode byte is sent to the Robot Controller with a value of 1. This byte and bit is defined in the default code.
(Check it out at
http://www.innovationfirst.com/firstrobotics)
To tell when autonomous mode has completed, auton_mode will become 0. You can also tell by the (possible) change of values on the Operator Interface inputs.
(This is
possible if and only if the driver changes the values on the Operator Interface after the autonomous mode has completed. This is an advanced tactic that some programmers will use to allow the robot to continue in autonomous mode, if they choose to do so. )
In practice, you can use a custom made dongle to simulate the change in the auton_mode bit in the Competition Port.
(This dongle can be found at
http://www.innovationfirst.com)
Hope this helps,