How does the LabVIEW development environment know that cRIO is running a Real-Time Application?

[Petru_Tarabuta]

I am working with a cRIO-9045 controller. I am able to successfully deploy Real-Time Applications to this cRIO. When the cRIO is running a Real-Time App, I sometimes want to stop the real-time app and run a VI on the cRIO in Interactive Mode (the mode where I can see and interact with the Front Panel of the cRIO VI).

To do this I right click the cRIO target in my project and select "Connect". After a few seconds I get a message saying "The target is already running a Real-Time Startup Application." (see screenshot below), which is correct. I then click OK and LabVIEW correctly stops the Real-Time App and deploys the VI in Interactive Mode.

My question is: How does LabVIEW know that an RT App is running on the cRIO? What VI, DLL, or query does the LabVIEW development environment call in order to determine that the cRIO is currently running a Real-Time app?

Motivation: I would like to use the same API or APIs in my Windows host application to determine if the various cRIOs connected to the host app are running Real-Time Apps or Interactive Mode VIs.

My setup:

Embedded device: cRIO-9045 controller running LabVIEW 2025 Q3 64-bit and drivers

Host machine: LabVIEW 2025 Q3 64-bit running on Windows 11

Many thanks,
Petru

[ZYOng]

The rtexe info is stored in /etc/natinst/share/lvrt.conf

See Deploying a LabVIEW Real-Time Startup Executable Without the LabVIEW Development Environment