The LabVIEW demos access the PHLIB DLL routines via the Call Library Function of LabVIEW. 
For details refer to the LabVIEW application note 088 How to Call Win32 Dynamic Link Libraries 
(DLLs) from LabVIEW provided National Instruments. Consult phlib.h or the corresponding manual 
section for the parameter types etc. Make sure to specify the correct calling convention (stdcall).

Strictly observe that the library is not re-entrant. This means the PH_xxxx library calls must be 
made sequentially in exactly the right order. They cannot be called in parallel as is the default 
in LabVIEW if you place them side by side in a diagram. Sequential execution must be enforced by 
sequence structures or data dependency. In the demos this is e.g. done by chained and/or nested 
case structures. This applies to all VI hierarchy levels, so sub-VIs containing library calls must 
also be executed in correct sequence.