Using Global Variables Instead of Get Refnum

[Alan Anderson]

It's certainly possible to use global variables to store RefNum values. The first year of the NI control system, it was normal to do it that way.

Two years ago we discovered a big drawback to not using the RefNum Registry, though. That's the mechanism that lets Test mode work to give you manual access to all the robot inputs and outputs that you use. So we use sort of a hybrid scheme, where we do a RefNum Set in Begin.vi, and also keep the RefNum in another place for easier and less typo-prone access.