Now that VI Scripting is available, I thought it would be handy to write a nugget about the VariantDataType VIs. In LabVIEW 8.0 and later, there is a set of VIs in vi.lib/utility/VariantDataType that are immensely helpful when writing code that involves parsing LabVIEW data types. There's too much in there for me to describe in a single nugget, so I encourage you to explore the VIs, and keep in mind these tips:
- You will usually use these VIs in conjunction with the Data Type property of the Terminal class. GetTypeInfo.vi is the best place to get started, as it is the VI that will return an enum describing the data type you wired in to the VI.
- A few of the data types listed in the type enum used by these VIs are
internal LabVIEW types that you should never encounter in a VI diagram.
- The more recent your LabVIEW version, the more useful stuff you'll find in the VariantDataType folder (like the Check for Contained Data Type.vi I added in LabVIEW 8.6).
- If you are using LabVIEW 7.x, a similar set of utilities resides in vi.lib/utility/GetType.llb. These VIs parse I16 array type descriptors, which were deprecated in LabVIEW 8.0 in favor of Variant-based type descriptors.
Most of the VIs in this folder have Context Help that describe their functionality. The "Get" VIs are probably going to be the most helpful for you since they are useful for obtaining information about existing data types. There are also some "Set" VIs that might be useful for more advanced applications that involve changing certain characteristics of certain data types.
