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Complete the following steps to create and configure a shared variable.

Note  You can create, configure, and host shared variables only on Windows or RT targets with the LabVIEW Real Time Module. You can use the DataSocket VI and functions to read or write shared variables from other platforms.

1. In the Project Explorer window, right-click a LabVIEW project library or folder under a project library and select New»Variable from the shortcut menu to display the Shared Variable Properties dialog box. You also can right-click an existing shared variable and select Properties from the shortcut menu to display the Shared Variable Properties dialog box.

Note  If you right-click a target or a folder that is not inside a project library and select New»Variable from the shortcut menu to create a shared variable, LabVIEW creates a new project library and places the shared variable inside.

2. Enter a name for the shared variable in the Name text box.
3. Select the data type for the shared variable from the Data Type pull-down menu. If you do not see the data type you want to use, select From Custom Control to use the data type of a custom control.
4. Select the type of shared variable you want to create from the Variable Type pull-down menu. Select Network-Published from the Variable Type list to create shared variables that you want to read and write on remote computers and targets on the same network. Select Single-Process from the Variable Type list to create shared variables that you want to read and write on a single computer.
   
   Configuration options vary depending on the Variable Type you select. LabVIEW modules and toolkits you have installed might provide additional shared variable types, configuration options, and limitations. Refer to the documentation for the LabVIEW module or toolkit for more information about the shared variable types, configuration options, and limitations that product adds to shared variables.
5. (Optional) If you select Network-Published from the Variable Type list, place a checkmark in the Use Buffering checkbox on the Network page to enable client-side buffering for the shared variable data. Depending on the data type you select from the Data Type pull-down menu, you might need to enter values in additional fields in the Use Buffering section.

Note  You can configure buffering only for network-published shared variables. If you publish a shared variable with less than 8 kilobytes of data, it can take up to 10 milliseconds for LabVIEW to send that data over the network. The Flush Shared Variable Data VI allows you to flush the buffer immediately and eliminate this delay.

6. (Optional) Place a checkmark in the Single Writer checkbox on the Network page to accept changes in value from only one writer at a time.
7. Click the OK button to create the shared variable.

You also can bind the new shared variable to an existing shared variable or to an NI Publish-Subscribe Protocol (NI-PSP) data item.

You also can use the NI Distributed System Manager to edit, create, and monitor shared variables outside of the project environment. However, if you deploy a LabVIEW project library that includes shared variables and then use the System Manager to create new shared variables in the same project library, the new shared variables exist only until you deploy the project library again.

If you have RT, FPGA, DSC, or an Embedded module installed, Change to Shared Variable Node appears as a new option in the shortcut menu when you right-click a control, indicator, or constant. You also can select Create»Shared Variable Node from the shortcut menu when you right-click an output terminal.

You also can use the Variable Reference property with the Variable properties to configure shared variables programmatically.

Note  You can create shared variables outside of a project library using the VI Server methods. To correct errors you might experience because the shared variable is not in a project library, you can use the AddSharedVariableToLibrary VI in the labview\vi.lib\Utility\Variable directory to programmatically add shared variables to a library. You also can use the CreateOrAddLibrary polymorphic VI to programmatically add a library to a project or a parent item such as a target, folder, or another library.

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