Steve,
Here's a copy/paste from the function description:
/*
This function allocates and initializes the data structures required by the NI-VXI library functions. This function reads the Resource Manager table and then copies all the device information into data structures in local memory. It also performs other initialization operations, such as installing the default interrupt handlers and initializing their associated global variables.
You must call this function at least once in your application. After the initial call, your application can directly access device information for any logical address. This function returns 0 the first time you call it successfully. You can call it multiple times thereafter, in which case it merely increments a counter
and returns 1.
Before your application exits, you should call CloseVXILibrary as many times as you call InitVXILibrary.
*/
