Creating I/O Alias Variables for Real-Time Scan Resources in LabVIEW 2025 and Later

An I/O variable is a type of shared variable that transfers I/O data. When accessed locally, I/O variables use the NI Scan Engine for single-point access to I/O data. When accessed remotely, I/O variables use the NI Publish-Subscribe Protocol (NI-PSP) for single-point or buffered access to I/O data. An I/O variable can communicate directly with a physical I/O channel or can transfer custom I/O data between an FPGA VI and a real-time (RT) VI running on the same target

The process for creating I/O variables in LabVIEW 2025 Q1 and later differs from previous versions. This article describes the steps required to create I/O variables in newer versions of LabVIEW.

Prerequisites:

• NI LabVIEW 2025 Q1 or later
• NI CompactRIO (cRIO) controller configured in a LabVIEW project
• I/O modules configured as Real-Time Scan Resources

1. Open or create a LabVIEW project.
2. Add your cRIO to your project.
3. Create a new library under your cRIO by right clicking the controller and navigating to New >> Library

4. Create a new shared variable by right clicking on the library and selecting New >> Variable

5. In the Variable category of the Shared Variable Properties Dialog Box, select I/O for the Variable Type

6. Enable the Alias radio button. 

7. In the Which Variable? field, enter the target channel using the following syntax: <RT controller name>\<Mod#>\Channel. 

Replace the placeholders with the values from your LabVIEW project:

• • RT controller name = Controller name as displayed in the project.
  • Mod# = Module identifier (for example, Mod1, Mod2).
  • Channel = Channel name on the module.

8. Enter the complete path. For example: RT CompactRIO Target\Mod1\AI1