An object-oriented development system for developing control schemes for facilities includes a device diagramming component for describing a physical description of a facility and a logical definition of a control scheme for the facility. The device diagramming component includes a mode for selecting device symbols representative of equipment or control functions used in facilities. The device symbols are selected from an object-oriented repository containing a plurality of device symbols and device objects. Certain types of device symbols relate to device objects containing logical instructions and configuration information relating to the represented equipment or control functions. The device diagramming component also includes a mode for interrelating in a graphical manner the selected device symbols and their corresponding device objects into a device diagram representing the physical description of the facility and the logical definition of the control scheme for the facility. A device logic developing component defines the logical instructions of the device objects relating to the equipment or control functions. Thus, the development system integrates in a graphical format the physical description of the facility with the logical instructions which define the control scheme for the facility. These logical instructions unify the configuration of analog/regulatory control with the configuration of discrete/sequential/interlocking control.