G-code is also the name of any word in a CNC program that begins with the letter G, and generally is a code telling the machine tool what type of action to perform, such as:
Set tool information such as offset. There are other codes; the type codes can be thought of like registers in a computer
:X position
:Y position
:Z position
:M code (another "action" register)
:F feed rate
:S spindle speed
:N line number
:R Radius
:T Tool selection
:I Arc data X axis
:J Arc data Y axis.
Different machine tools, however, may use the same code to perform different functions: even machines that use the same CNC control. Some may have said that "Fanuc" G-code is standard, but that is a myth.
A standardized version of G-code known as BCL is used; but on very few machines.
G-code is understood by machine tool controls, and some machinists.
G-code is spoken by CAM software such as Smartcam, Gibbscam, Featurecam, Edgecam, Mastercam etc. Such software must be customized for each type of machine tool that it will be used to program.
Some CNC machines use "Conversational" programming, which is a wizard-like programming mode that either hides G-code or completely bypasses the use of G-code.
