Units
As already discussed in Unit 4, the G-codes are used to specify the units to be used in a program. The two possible codes that form a group are:
- G20 or G70 for inch units
- G21 or G71 for mm units
G20 or G70 Inch Input
In Fanuc controls, G20 is generally used to specify inch units in a program. It is possible to change it to G70 to comply with the ISO standard by the use of special parameters in the control. In this course, we will stick to G20. The command is modal and remains in force till it is changed by G21 (mm mode) command.
G21 or G71 Metric Input
In Fanuc controls, G21 is generally used to specify mm units in a program. It is possible to change it to G71 to comply with the ISO standard by the use of special parameters in the control. In this course, we will stick to G21. The command is modal and remains in force till it is changed by G20 (inch mode) command.