You can place down a Property Node anywhere in your code and select the property called Application >> Target >> Operating System. This will output at Run-Time the operating system where your code is running. You can wire the output of this property node into a Case Structure and then execute the correct subVI based on the operating system.
You will probably have to do some more work than this. It's entirely possible that your Linux subVI will have a broken run arrow in Windows if it tries to call a shared library or do anything Linux-specific. In that case it won't be enough to try to put it in a case structure, since your main app won't be able to run if any of its subVIs are broken. In that case, you will need to call your platform-specific VIs dynamically using VI Server based on the current operating system. That means LabVIEW won't decide which VIs to load until run-time, so you can only load the correct implementation.
On a side note, LabVIEW 8.x has a nice feature that makes this much easier. There are new nodes that resemble Case Structures called Conditional Disable Structures that operate much like an #ifdef statement in C. You can set them up to only compile code in one case based on a number of different symbols such as the operating system or custom symbols you create. You can have broken wires or broken subVIs in the disabled cases and your application can still run. Using this method, you could set up your application to switch automatically based on the environment that loads it without dynamically calling your VIs.
Jarrod S.
National Instruments
