Session Reference Counting

NI Switch Executive uses a reference counting scheme to manage open session handles to an NI Switch Executive virtual device. Each call to the niSE Open Session VI or the niSE_OpenSession function must be matched with a subsequent call to the niSE Close Session VI or the niSE_CloseSession function.

Multiple calls to the niSE Open Session VI or the niSE_OpenSession function with the same virtual device name always return the same session handle. Only after all session handles are closed to a given virtual device can NI Switch Executive disconnect its communication with the IVI switches. Session handles can be used safely in multiple threads of an application.

Note  When using an NI Switch Executive virtual device in an ADE, always allow the application to complete its call to the niSE Close Session VI or the niSE_CloseSession function. If you abort or halt the execution of your program before calling the niSE Close Session VI or the niSE_CloseSession function, the application may leave the session open. When a session remains open, all previous connections continue to exist.

Tip  If you are debugging and prefer not to call the niSE Close Session VI or the niSE_CloseSession function, you can call the niSE Disconnect All VI or niSE_DisconnectAll function immediately after calling the niSE Open Session VI or the niSE_OpenSession function to ensure a known startup state.