TOPICS

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TOPICS

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Programmatic Control of User

Interface

A. VI Server

B. Property and Invoke Nodes

C. Implicitly and Explicitly Linked Property and Invoke

Nodes

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A. VI Server

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VI Server

LabVIEW organizes and operates on its parts (front panel,
button, arrays, etc.) within an architecture called VI Server, which
is object oriented.

Terminology

:

• A class defines what an object is able to do, what operations it

can perform (methods), and what properties it has.

• An object is a member of a class.

• Properties are the attributes of an object.

• Methods perform an operation on an object.

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VI Server—Class Hierarchy

VI

Application

Generic

GObject

Control

Boolean

Cluster

Etc.

Etc.

Generic

GObject

Control

Boolean

Pets

Dogs

Labrador

Poodle

Cats

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B. Property and Invoke Nodes

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Property Nodes

• They read and write the properties

of an object.

• They allow you to make these

modifications programmatically.

• There are two types of Property Nodes:

– Implicitly linked

– Explicitly linked.

• They can have multiple properties and execute from top to

bottom.

– By default, if an error occurs on one of the terminals, the rest does not

execute and error is output at error out terminal.

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Invoke Nodes

•

Use the Invoke Node to perform actions, or methods, on
referenced items (VIs, controls).

•

Methods can have parameters or return values.

•

There are two types of Invoke Nodes:

−

Implicitly linked

−

Explicitly linked.

Method Name

Parameters

DEMONSTRATION

Creating Property and Invoke Nodes

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C. Implicitly and Explicitly
Linked Property and Invoke
Nodes

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Implicitly and Explicitly Linked
Invoke/Property Nodes

Explicitly Linked

(requires reference)

Implicitly Linked

(color/ label for data type/label)

Property

Node

Invoke

Node

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VI

VI

Main VI

Main VI

SubVI

Implicitly Linked Property Node

Explicitly Linked Property Node

Control References

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SubVI Front Panel

SubVI Block Diagram

Edit»

Create

SubVI

1. Select the portion of

the block diagram that
will be in the subVI.

2. Select Edit»Create

SubVI; LabVIEW
automatically creates
the control references
needed for the subVI.

SubVIs and Invoke/Property Nodes

DEMONSTRATION

Creating References for Property
and Invoke Nodes; Selecting a Class