What is the main difference between...

[Michelle1892773]

What is the main difference between LOCAL VARIABLE, REFERENCE, PROPERTY NODE and INVOC. NODE?

Can u show this with an example in a VI using all these?

[GregFreeman]

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Michelle1892773 wrote:

What is the main difference between LOCAL VARIABLE, REFERENCE, PROPERTY NODE and INVOC. NODE?

Can u show this with an example in a VI using all these?

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Basic overview. Someone can go into more depth if they want.

Local Variable - Correlates to some location in memory that holds information. Based on the data type, it looks at that location and interprets the 1's and 0's as either a double, integer, string, structure(cluster), etc.

Reference - ill leave the details of this to someone else I can't give a decent explanation.

Property node- sets different "properties" of a control/indicator etc. One of the properties is value so that works similar to a local variable. However, you can set much more than that. For example, with controls you can set the property of visible, not visible, color, etc etc.

Invoke node - invokes some "method." i.e. calls some function to act on something

These may not be the best explanations, or even 100% correct. But it should get you started. I'm sure someone else will build on this.

[SynergyMike]

I am still a novice at LV, but I would describe a reference is simply the name of something. This name is then used as an input on something (could be a VI, could be a node) that works with the something that is named.  Let's say you take a string indicator and you want to programmatically set it to blank.  You could wire an empty string constant directly to the indicator, except that you can't do this if you have something else wired directly to it elsewhere.  You could use a property node to set its value also, and you can do this one of two ways.  You can create a property node based on the indicator, or you can create a reference to the indicator and wire it to a generic property node (working with LV 7.1 here - assuming later versions are still similar in this regard).

Regards,

Michael Tracy

Synergy Microwave

[RDR · Accepted solution]

(From the LV Help)

Local Variable: http://zone.ni.com/reference/en-XX/help/371361F-01/glang/local_variable/

Property Node: http://zone.ni.com/reference/en-XX/help/371361F-01/glang/property_node/

Invoke Node: http://zone.ni.com/reference/en-XX/help/371361F-01/glang/invoke_node/

Building VI Server Application: http://zone.ni.com/reference/en-XX/help/371361F-01/lvconcepts/building_vi_server_applications/

You can also find this information by searching in the LabVIEW Help on your PC or by searching the online help:

http://zone.ni.com/reference/en-XX/help/371361F-01/