When the command station is sending commands to a loco address that is in-use on one of the DT300's throttles and that address is being changed by another throttle or computer, it will cause the DT300 to “click” every time it sees a remote throttle change its locomotive settings.
If that locomotive is in the active throttle, its speed display will also show the changes. This is called slot following. This allows two DT throttles to run a single locomotive address with both throttles being able to send commands to the loco. Both throttles will show the current speed and direction of the locomotive in their displays.
Slot following is useful for training new operators. The supervisor can “steal” a locomotive that is selected on a trainee’s throttle and be able to “look over the trainee’s shoulder” and closely supervise that locomotive’s control. The supervisor can gain instant override control without having to physically “grab” the trainee’s throttle. This lets you have unskilled visitors participating and enjoying operations without too much anxiety for either party.
Slot following also allows a computer on LocoNet to run CTC and routing control programs with automated control over locomotives. The computer can control speed and stop engines automatically while letting the engineer with the throttle in his hand know what is happening.
Slot following when started accidentally can make you think that something is wrong with your loco because you may not appear to be in control of the loco. The loco will act upon the last command sent to it by either throttle that is controlling it. For example, if you set the speed to 0 and then the other operator set the speed to 50%, you would be expecting the loco to be stopped but it would be taking off at half speed.