METHOD AND APPARATUS FOR PROVIDING ATTRIBUTE NODES IN A GRAPHICAL DATA FLOW ENVIRONMENT

A system and method for providing attribute nodes in a data flow diagram which allow a user to programmatically access various parameters of a control or indicator. In this manner, a user can programmatically make changes that affect the output or appearance of controls and indicators. A user can also access these parameters interactively during execution of a block diagram. A user can creates an attribute node containing one or more attributes corresponding to controls that affect a parameter of the control, such as the color used for the respective display, the visibility of the control, the scales or cursor position for respective graphs or charts, etc. The purpose of an attribute node is to affect the visual output of a control provided on the front panel depending on events which occur during execution of a VI or on user input during execution of a VI. An attribute node thus allows the execution subsystem to monitor user interaction by reading attribute data that previously was not available to the program. An attribute node allows two types of operations, these being reading an attribute node or writing to an attribute node. These operations of reading and writing an attribute node can be performed either by a block diagram during execution, wherein the user has programmed the block diagram to perform this function, or interactively by the user during execution. The process of writing to an attribute node refers to the execution subsystem updating an attribute of a control in the front panel display to reflect an attribute that has been set programmatically in a block diagram. The user can also "write" to an attribute node by providing input to a control in the front panel during execution of a block diagram. Reading an attribute node refers to the execution subsystem reading the value of an attribute for a certain control during block diagram execution that may have been changed by the user, or may have been changed during execution of a VI by the execution subsystem. Reading an attribute also refers to the user viewing changes to the attribute during execution.