Right-click a LabVIEW project library or folder within a library and select New»Variable from the shortcut menu, or right-click an existing shared variable and select Properties from the shortcut menu to display the Shared Variable Properties dialog box and this page.

Use this page to set the basic options for a shared variable. You also can use the Variable Reference property with the Variable properties to configure shared variables programmatically.

This page includes the following components:

Option Description
Name Specifies the name of the shared variable.
Variable Type Specifies the scope of the shared variable. Select Network-Published from the pull-down menu if you want to share the shared variable data across a network. Select Single-Process from the pull-down menu if you want to share the shared variable data among VIs on the local computer. 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.
Data Type Specifies the data type of the shared variable. Select From Custom Control and enter a path or browse to a custom type control to use a custom control or typedef as the data type of the shared variable. The data type you select appears in the field below the pull-down menu. LabVIEW modules and toolkits you have installed might provide additional shared variable data types. Refer to the documentation for the LabVIEW module or toolkit for more information about the shared variable data types that product adds to LabVIEW.
Configure Fixed Point Displays the Configure Fixed Point dialog box. This button appears only if you select Fixed Point from the Data Type pull-down menu.
Enable Network Publishing Specifies whether to share the shared variable data across a network. This option is always enabled for network-published shared variables.
Enable Timestamping Specifies if a timestamp value is recorded each time the single-process shared variable reads data. To view the timestamp information and add a timestamp output to the Shared Variable node, right-click the Shared Variable node and select Show Timestamp from the shortcut menu. The Enable timestamp component is available only for single-process shared variables. The timestamp always is enabled for other types of shared variables.
Enable Aliasing Binds the shared variable to an existing shared variable in the active project, an existing shared variable in another project, or an NI Publish-Subscribe Protocol (NI-PSP) data item on the network. This component is available only for network-published shared variables.
  • Bind to:—Specifies whether to bind the shared variable to an existing shared variable in a project or an NI-PSP data item on the network.
  • Path—Specifies the path to the shared variable or data item to which you want to bind the shared variable you are configuring. The path to an NI Publish-Subscribe Protocol (NI-PSP) data item consists of the computer name, the name of the process in which the data item resides, and the data item name: \\computer\process\data_item
  • Browse—Displays the Browse for Variable dialog box from which you browse to the shared variable or data item on the network to which you want to bind the control.
  • Access Type—Sets whether the shared variable writes or reads data. If you select read only or write only, you can create shared variables that are configured only to read data or write data, respectively. When you right-click the shared variable that is bound to a source that is read or write only, LabVIEW disables the Change To Write and Change To Read options in the shortcut menu.
Direction Specifies the data transfer direction of a user-defined I/O variable. This option is available only for user-defined I/O variables.
Use Buffering

Enables you to store data from the variable in a first-in-first-out (FIFO) buffer. The shared variable overwrites the first value in the FIFO if the FIFO reaches capacity.

You can use buffering only for network-published shared variables.
  • Number of arrays—Specifies the number of arrays of elements the buffer can contain. This control appears only for array data types.
  • Number of elements (type: xxx)—

    Specifies the number of shared variables the buffer can contain. The data type you select in the Data Type pull-down menu determines the variable xxx. This control does not appear for all data types.
Single Writer

Sets the shared variable to accept changes in value from only one target at a time.

This component is available only for network-published shared variables.

Selecting this option ensures that the shared variable write operation is not affected by another instance of LabVIEW.exe. The Shared Variable Engine restricts writing to a single VI on a single computer. The first instance of LabVIEW that connects to the shared variable can write values, and any subsequent instances cannot. When the first instance disconnects, the next instance in the queue can write values to the shared variable. LabVIEW notifies writers that are not allowed to write to the 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.