A method of operating a data processing system running a visual programming language program development system to represent an instrument having a plurality of controls disposed in a layout pattern relative to one another in a visual program. The instrument block that corresponds to the instrument includes a GUI control panel display having a plurality of virtual controls and a connection region. Each virtual control causing the instrument to execute a function that alters the physical state of the instrument. The connection region is associated with the GUI control panel display. The connection region has a pin that is associated with one of the virtual controls and provides a programming interface for connections to other pins in the visual program. The association between the one of the virtual controls and the pin is provided in response to user input during a design phase of the program.