Global variables are custom variables created in LabVIEW, so there are not any standard global variables that ship with LabVIEW or anything. This means that if your VI uses a global variable that wasn't given to you along with the VI, then you will have to create a new one from scratch. If you don't have any idea about what that global variable should be, you can use the data type that is connected to it in your VI as a clue. I've linked the help documentation on creating global variables here.
Kind Regards,
E. Sulzer
Applications Engineer
National Instruments
