Global VariablesGlobal Variablesin LabVIEW Tutorial by Harris Pharrin LabVIEW Tutorial by Harris Pharr

What are Global What are Global variables?variables?

Global variables are Global variables are used to access and used to access and pass data among pass data among several VI’s that run several VI’s that run simultaneously.simultaneously.

Can control multiple Can control multiple VI’s and read their VI’s and read their results from one front results from one front panel.panel.

JK-Flip FlopJK-Flip Flop

Global Variables control Global Variables control input values and clock input values and clock along with global stop along with global stop button to control a JK-button to control a JK-flip flop running via a flip flop running via a JK.VI and a sub via JK.VI and a sub via JK_sub.VI. JK_sub.VI.

Output values Output values displayed on VI’s of all displayed on VI’s of all 3 front panels of each 3 front panels of each respective VI.respective VI.

JK FF JK FF Truth TableTruth Table

To the right is a JK FF To the right is a JK FF truth table which truth table which can be verified in can be verified in with using the with using the following VI.following VI.

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Front Panel VIFront Panel VIOn the left are the Global Variable Input controls On the left are the Global Variable Input controls and on the top right is the JK VI and SUB VI front and on the top right is the JK VI and SUB VI front panels.panels.

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Block DiagramBlock DiagramThe top diagram is the simplified JK sub .VI and on the The top diagram is the simplified JK sub .VI and on the bottom is the JK VI. The global variables all have Global bottom is the JK VI. The global variables all have Global indicated on their label.indicated on their label.

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VI in ActionVI in ActionYou can verify the JK FF’s truth table with this video You can verify the JK FF’s truth table with this video showing the VI being operated from the Global showing the VI being operated from the Global variable front panel.variable front panel.

https://harrispharr.web.unc.edu/global-variables/https://harrispharr.web.unc.edu/global-variables/

Tutorial can be found on my website atTutorial can be found on my website at