Labview programming environment

The LabVIEW graphical programming environment can be used to design and analyze a signal processing system in a more time-efficient manner than with text-based programming environments. This chapter provides an introduction to LabVIEW graphical programming. Also see [link] , [link] , and [link] to learn more about LabVIEW graphical programming.

LabVIEW graphical programs are called virtual instruments (VIs). VIs run based on the concept of dataflow programming. This means that execution of a block or a graphical component is dependent on the flow of data, or, more specifically, a block executes after data is made available at all of its inputs. Block output data are then sent to all other connected blocks. With dataflow programming, one can perform multiple operations in parallel because the execution of blocks is done by the flow of data and not by sequential lines of code.

Virtual instruments (vis)

A VI consists of two major components: a front panel and block diagram. A front panel provides the user interface of a program while a block diagram incorporates its graphical code. When a VI is located within the block diagram of another VI, it is called a subVI. LabVIEW VIs are modular, meaning that one can run any VI or subVI by itself.

Front panel and block diagram

A front panel contains the user interfaces of a VI shown in a block diagram. VI inputs are represented by controls such as knobs, pushbuttons and dials. VI outputs are represented by indicators such as graphs, LEDs (light indicators) and meters. As a VI runs, its front panel provides a display or user interface of controls (inputs) and indicators (outputs).

A block diagram contains terminal icons, nodes, wires and structures. Terminal icons, or interfaces through which data are exchanged between a front panel and a block diagram, correspond to controls or indicators that appear on a front panel. Whenever a control or indicator is placed on a front panel, a terminal icon gets added to the corresponding block diagram. A node represents an object or block that has input and/or output connectors and performs a certain function. SubVIs and functions are examples of nodes. Wires establish the flow of data in a block diagram, and structures control the flow of data such as repetitions or conditional executions. [link] shows front panel and block diagram windows.

Icon and connector pane

A VI icon is a graphical representation of a VI. It appears in the top right corner of a block diagram or a front panel window. When a VI is inserted into a block diagram as a subVI, its icon is displayed.

A connector pane defines VI inputs (controls) and outputs (indicators). One can change the number of inputs and outputs by using different connector pane patterns. In [link] , a VI icon is shown at the top right corner of the block diagram, and its corresponding connector pane, with two inputs and one output, is shown at the top right corner of the front panel.