MOHD ASIF HASAN

—Computer Numerical Control (CNC) machines are widely used in production industry. However, there fullest utilization is yet to be achieved. In order to make use of these machines to their full potential require an understanding of their hidden or not so well known capabilities. One such capability is Macros. Macros are simple part-programs which reside in the memory of the controller and are called using a specific code for the macro. All sort of canned cycles are basically Macros. Fanuc offers in its CNC controllers the optional feature to program CNC Machines using Macros which is also known as Parametric Programming. In order to develop Macros, Fanuc offers Custom Macro B which is similar to any computer programming language. Custom Macro B offers many CNC related features in addition to features of any computer programming language. Custom Macro B can be accessed at G and M code level, which means that it can be combined with manual programming techniques of CNC machines. Although, Subprograms are the first logical step into the macro development, the major difference between the two unique programming methods is the flexibility macros offer. To achieve this flexibility, Macros make extensive use of Variables. Local Variables and Common Variables are two such variables which are primarily used for the development of Macro programs. In order to address an inherent limitation of Local Variables in some situations, Common Variables are used for Macro development. This paper discusses use of Common Variables for the development of Macros in particular and a conceptual framework for the use of variables in Macros in general.